Category Archives: Electrical & Security

Electrical & Security

Honda EU22i Generator for home backup power

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Link to mobile inlet protection version

link to original power transfer/backup blog

We recently had a 4 hour power outage due to a blown street joint and found out I could now hardly lift my existing generator, so it was time for a rethink.

My previous blog covers the internal transfer switch enabling my consumer unit to be safely switched from utility power to local generation, that bit of the system has not been altered.

This blog covers the Honda EU22i generator, house inlet and circuit protection.

Generator

EU22i ManualDownload

I gave some thought to the replacement of my old open frame generator, and the following points were key for me (in no order):

  • Reliability
  • Manageable weight
  • Low running noise
  • 100% Sine Wave
  • Min 1800w output
  • Machine history
  • Cost
  • Serviceability

Although expensive, the EU22i met my requirements and was purchased from a local Honda approved dealer which increases my confidence in aftercare.

In case of extended running being required, I bought from eBay an additional external petrol tank and petrol lines for this reason.

Generator External Inlet Build

Construction was very straightforward, I start by making a dimensioned drawing using Visio of the enclosure and all parts to be used, this allows me to play about with the layout and finally print the front label which I use as a cutting template for the any holes required.

The parts were relatively inexpensive apart from the hour meter which functionally wasn’t required but is a ‘nice to have’ to monitor the generators onload usage to the house.

House Connection

The original connection from the generator to the transfer switch has been removed and replaced with one containing a voltage and current protector, a 30mA RCCD and an hour meter to monitor time off grid.

The above image shows the standby generator inlet powered externally from the EU22i without any load, the voltage and current protector GPS8-02), is displaying the actual generator voltage of 244v AC, the voltage and current protectors internal contactor will disconnect if any of the follow occur:

  • Voltage out of 210v – 252v range
  • Current over 7.5A

The Red LED indicator illuminates when the generator is running with the RCCD ON and controllers output is within the set parameters.

GPS8-02 Instruction ManualDownload

Image of power transfer switch below the consumer unit in the garage, below is an image of the consumer unit RCBO descriptive labels which are either Red or Green, if RED, then they must be turned OFF in advance of the generator power being switched over with only the GREEN left ON.

Electrical Connection Overview

First thing to note is that the generator is separated from the Utility power system by a ‘break before make’ switch, specifically designed for the purpose of external network protection, with this arrangement it is not possible to ‘back feed’ into the network and possibly cause injury to downstream workers.

The house supply is TN-C-S or PME, I had previously installed an Earth Rod for two reasons, the first was to remove reliance on the DNO protective conductor being the single point of failure and the second was to ‘Ground’ the otherwise ‘floating neutral’ of the legacy open frame generator in order for the RCDs to operate.

I wanted to retain the neutral – earth bond on my new Honda generator and so I contacted Honda Directly for the information.

NOTE: Earthing is the biggest area of debate regarding home generators, please do your own research on this complex area.

Honda Position on a Bonded Neutral

After many frustrating phone calls and emails both to Honda UK and my Honda dealer regarding conversion from a floating earth to a bonded neutral – earth on my EU22i generator, I was told the information I required was in the Service and Warranty Book which I don’t have, anyway below is the relevant information:

In light of the above information I bought a red plugtop and internally linked the Earth and Neutral together which I will plug in one of the generators outlet sockets whilst using the other socket to feed the transfer switch.

My Initial Concern Over a Bonded Neutral

I have retained this section for information only to show my thought process and rational for not simply jumping in and bonding the Earth to Neutral with the consequential risk of costly damage.

The above is the wiring schematic of the Honda EU22i with the addition of voltage measurements I have taken and a guide image inlay of a split load transformer.

I wanted to establish if the generators chassis ground screw was connected to anything other than the chassis, ideally I was looking to see if the neutral and chassis were directly connected, this would give me a fixed reference voltage and replicate my existing incoming electrical supply configuration.

Results:

  • Socket earth pin to chassis ground screw – Continuity and 0v AC
  • Socket live pin to chassis ground screw – 120 v AC
  • Socket neutral pin to chassis ground screw – 120v AC
  • Socket live to neutral – 244v AC

Conclusion before Honda clarification

The generators inverter output is split phase, effectively two live conductors when measured to the chassis, therefore, bonding the neutral to the chassis would cause a direct short circuit of one half of the inverters output and I’m assuming ‘magic smoke’ would soon follow.

In light of this, I have made no modifications to the generators output (no N-E plugs etc) and instead opted to earth the generator to the house earth via the plug and add a global 30mA RCCD on the generators output.

The consumer unit does have RCBO’s, but I’m not bothered by selectivity of device operation in an outage, overcurrent again will be globally managed by the GPS8-02.

12v DC

I don’t envisage using the generators 12v DC output, however, I did measure the voltage and though I’d share the results:

  • Eco Mode – no load voltage = 16v DC
  • Eco Mode – across 21w load = 11.2v DC
  • Non Eco Mode – no load voltage = 33v DC
  • Non Eco Mode – across 21w load = 16.7v DC

Just one to note!

MkII Inlet Version

A family member asked me to build generator and load protection for his home setup, so I tweaked my static version for portable use and have done a write up on it should I need to make more.

As you can see, this version is fully portable and can be connected inline either at the generator or the load end, also it has a rating of IP65 offering a level of protection water ingress.

The clear lift up flap allows the status of the device to be observed without exposing the internals to moisture.

Construction was straightforward, the most time on the build was spent waiting for some of the parts to arrive from Aliexpress.

Pleased with the finished unit and wish I’d done something similar for mine 🙂

SES-16 Instruction Manual & Build InfoDownload
Electrical & Security

Screwfix Concrete Mixer Electrical Repair

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Came to use my mixer after a year in storage and everything seemed ok, the motor ran when turned on but after a few moments the motor stopped and it took a few presses of the button to get it started again.

Tipping the mixer to empty it, the mixer yet again stopped but would not restart until it was tilted back.

This random stopping was really frustrating, so off came the wiring enclosure cover to see if any cables have come loose, but nothing obvious other than signs of water ingress which must have happed when the mixer was in storage.

Fortunately I managed to repair it for under £10!

Rusted screws and slight discoloration around the switch connections, but apart from that nothing really immediately obvious as to why it keeps cutting out, so I ordered a new ‘No Volt Release’, Start/Stop module from Amazon, the one selected was a Dacvgog CK21 Electromagnetic switch for concrete cement mixers 240V:

Once arrived, switch removal was very easy by depressing the internal wings on either side and popping out, I made the connections to the new switch before pushing into the hole with a reassuring click.

Power on and everything works as it should with no intermittent stopping irrespective of being tilted or not, to check it wasn’t a fault with the motors thermal fuse internal connections, I took the old starter switch apart to check its condition:

As you can see there is extensive water damage to the Start/Stop switch internally, but only minor signs on the outside, hopefully everything will be fine now 🙂

Rough wiring drawing HERE.

Electrical & Security

Pyronix Euro46 Alarm Automatically Locking the Garage Door

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3 January 2023

When I installed my Pyronix Euro46 house alarm, the garage was designed as a separate area allowing it to be set independently of other areas, to confirm final setting and to start the entry timer, a small lever microswitch was fitted to the sliding locking mechanism on the garage door.

Microswitch to detect lock position

When the door is locked, the pin is over to the right; the picture above shows the door in the unlocked state.

This arrangement works really well, the biggest problem is when I come to set the alarm from within the house, only for the alarm to indicate that I had forgotten to lock the garage door, meaning I have to go outside to the front of the house and lock the door, a real niggle 🙂

The image shows that the garage door is not locked, but now pressing the Lock Garage Icon will do this for me.

Locking Process

This is in two parts, the first being how the mechanically lock the garage door and the other is how electrically this would work with the alarm system.

The garage door can be locked with a key from the outside or by sliding the internal locking pin to the right, sliding the pin takes quite a force to manually move, so I took a punt and bought a 12v Micro Linear Actuator from Amazon, this has a 30mm stroke and can apply a force of 60N (6kg) and turned out to be ideal.

I mounted the actuator on a small sheet of 1.5mm aluminum and with the actuator fully extended, aligned the end of the arm to the full throw of the locking pin and tested operation with a battery, once happy, I used self tapping screws and affixed the aluminum to the garage door cross member.

The wires from the actuator and microswitch are taken off the door by a flexible door loop.

The triggering of the actuator was the next part to look at.

The actuator has an inbuilt limit switch, stopping the motor at each end of the arms travel, to operate, apply 12vDC and this will extend the actuators arm, reversing the 12v polarity will causes the actuator arm to retract and stop.

I could have physically connected the actuator arm to the locking pin enabling me to both lock and unlock the door electrically, the only problem with this is that the external euro lock would no longer work, as the locking pin would be held in position by the actuator arm which cannot be manually retracted.

Actuator Logic

  • The garage door to automatically lock when setting the alarm,
  • Ability manually trigger the locking actuator from the ProControl+ App on my phone,
  • If the door is locked the actuator has no need to operate.

Programming Euro46

The Pyronix Euro46 has a comprehensive number of programmable outputs and options which made the actuator logic easy to setup via the ‘InSite’ software.

The garage has a PSU/ZEM8 which has 4 programable outputs, I used two of these Outputs for this project, Outputs 2 & 3.

Output 2 was programmed to ‘Follow’ (Output type 35) the switch state of the lock microswitch (Input 33), if the lock is closed, the Output would go LOW enabling Relay 1 to energize, the contacts of this relay apply or remove a 12v positive to the trigger of Relay 2.

Output 3 was programmed as ‘Gate’, the gate is comprised of a combined OR logic within the panels software.

Output 3 would go LOW enabling Relay 2 to energize if the positive from Relay 1 was available.

Output 3 LOW conditions-

  • if the Exit time starts for Area ‘D’ (Output type 280),
  • OR
  • the Apps virtual Output is triggered (Output 0171 timed for 8 seconds).

Relay 2 simply changes the polarity of the 12vDC to the actuator, in the relays OFF state, 12v is applied to retract the arm, in the ON state the arm extends, once Relay 1 operates, Relay 2 will drop out causing the arm to retract.

Relay Wiring

Lock SchematicDownload
All connected up with the door lock relays housed within the PSU/ZEM8 enclosure, 12v supply to the actuator is fed from the PSU and further fused down to 1A.

Operation

Electrical & Security

Pyronix Euro 46 Home Alarm Installation

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Front of property showing external sounder and CCTV cameras with infra-red illuminators on.
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Background

I installed my original alarm system in 2006 which was monitored by Custodian Alarm Receiving Centre with a police response. The Control & Indicating Equipment was Scantronic 9851 with two remote keypads, all detection devices throughout the property were hardwired and both front and rear sounders were live.

The end station was installed out of the way in the loft:

I decided in March 2020 to ‘get back on the tools’ and install a new hybrid system with App functionality, the system also had to be remotely programmable, have flexible circuit input/output attributes to allow for third party integration and have a comprehensive range of detection and system devices.

Looking at the marketplace range of products, training packages offered by the manufactures and distribution availability, I opted to install a Pyronix Euro 46.

I must admit to not liking the old CastleCare range as they looked a bit too clunky for a domestic environment when compared to their competitors offerings, hence, I originally installed a Scantronic panel, however, after installing it, I really like the no nonsense, intuitive keypad and the area LEDS showing the set status is really handy as a quick visual verification that the system is armed.

euro-46-v10-datasheetDownload

System Topology

The wiring architecture is very straight forward with a data buss from the blind end station going to either or Zone Expansion Modules (ZEM8), Wireless Expansion Modules (ZEM-32WE), Output Modules (EURO- OEM8R8T) or Keypads or a mix and match of these to suit the systems design configuration.

016-Pyronix-Panels-System-TopograhyDownload

In my case I needed two 8 circuit zone expanders, 1 output module, 4 keypads, 1 wireless 32 zone expander and 2 remote key fobs, as this is my test system as well, one of the keypads is local to the panel acting as the engineers keypad.

The Scantronic system used resistors in each detector enabling a Fully Supervised Loop, this means that two wires can monitor the following circuit status:

  • Device Open
  • Device Closed
  • Tamper – Open Circuit
  • Tamper – Short Circuit
  • Detector Anti-Mask

Installation

I decided to bring the end station out of the loft, two main reasons for this, the first being access for servicing and the second is the elevated temperatures in the summer are not healthy for batteries and will shorten their life.

I have a small unused cupboard which is ideal so the cabling was re-routed from the loft, or new runs installed.

Cables ready for second fixing.

Access to zone expansion modules is less critical, so one ZEM8 is in the airing cupboard and others modules are in the loft, as below.

These pictures below show the installation of a ZEM8 –

The house was prewired for an alarm system during construction with the intention of the End Station going in the airing cupboard, as this was not the case when I first fitted the system, all cables were extended using junction boxes.
ZEM8 mounted on the wall with detection circuit cables entering via rear access slots.
Completed ZEM8 with circuit descriptors clearly visible to aid fault finding or servicing.

The control equipment is able to monitor all ZEM8 parameters, such as voltage, circuit status and circuit resistance for remote diagnostics or virtual servicing.

The end station was mounted on a stand off board, this board was also home for my external GJD lighting system which is integrated into the alarm system along with CCTV recording and notification.

Smoke detectors were incorporated into the alarm system after a modification to a interlink monitor, details are HERE.

Completed setup, comprising a 3A Power Supply Unit, Euro 46 end station, relay output expansion module, external lighting end station and Sonoff external lighting override module.

I’ve not gone into detail regarding the type and specific location of detection devices for obvious reasons, that said, adding devices to the system is incredibly easy and the programming using Pyronix InSite UDL software is a doddle once you have an understanding of their menus and command functions.

As I had not used Pyronix equipment before, I made a circuit test switch box and explored on the bench all the programming options of the euro 46 before I started my system swop over, this worked really well for me, so money well spent in making it.

Details of the circuit input test box : HERE.

Tricky Keypad Install

One aspect of the installation that was a bit tricky was the cabling to the rear door keypad.

I’m old school and prefer to home run cables wherever possible, plus the option to use the keypads onboard detection circuits was not possible as this allowance had been used elsewhere, this meant that the existing rear door contacts cable could not be converted to a data buss.

I could have opted for a wireless keypad, but where would be the fun in that!

Making sure I avoided any cables in the switches safe zone, I drill at a tight angle into the cavity void.
With the external fan guard and sleeve removed, the cable was fished out from the keypad location, the external lighting sensor was then removed and the cable fished to that, before going up into the loft, all completely hidden.
All done 🙂

Sounders

The external sounders are Delta Bell, one is configured as a Self Activating Bell whilst the other is configured as a Self Contained Bell, monitoring is via an Ethernet module to the Pyronix servers (this is an annually charged service).

deltabell-x-datasheetDownload

Conclusion

I’m very happy with the system, it is easy to use, responsive via the app and flexible, integration into Hikvision cameras is a bonus, really enjoyed this swop over, not like some I’ve been involved with in the past!

Updates

6th December 2022 – I noticed that on the furthest keypad (RKP0), that everything was fine when using the tag to set & unset, but if I were to enter the code to unset the system, the display would be very slow to respond and after a short while a Comms Error would be generated.

Although the supply voltage was within tolerance, it was in the lower band, I therefore installed a Euro-ZEM8-PSU, this now feeds the RKP directly and I also took the opportunity to remove two detection zones from the keypad and migrated them to the ZEM8, making for a more logical installation, also the ‘Area Set’ LED programmable output was also moved from ZEM address 02 to the new ZEM8.

The issue has now been resolved.

3rd January 2023 – Added automatic garage locking controlled via outputs from the Euro46 panel, blog on this can be found HERE.

Electrical & Security

MiniSun 19500 Dimmer & Switching Modification

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I have previously fitted a MiniSun 19500 fan and was very pleased with its performance considering the cost of the unit is quite low, however, I did have a few minor niggles relating to the lack of space in the base to fit the controller and the lack of lamp dimming.

The modifications I wanted to make were:

  • Dimming of the lamps as the fan is being installed in a bedroom
  • 2 way light switching i.e. switching on/off from the wall or remote control

Note: The fan I was installing was new, but out of warranty, this modification will invalidate any outstanding warranties.

What’s in the box

MiniSun 19500 Fan InstructionsDownload

Included, but not shown above, are two, non dimmable 4W LED Golfball lamps (SES/E14).

For a standard installation, the controller uses plugs to connect to the fan motor and fan lights, with the controller then being crammed into the fan base, it is doable, but tight, so be warned.

Once power is applied, the light on/off and 3 motor speeds are selected and controlled by the remote control with the fans Infra-Red (I/R) sensor being adhered to the ceiling.

Drawing showing controllers inputs & Outputs

Modification

I needed to do a few enabling tasks before the ceiling fan was fitted, this meant the removal of the existing bedroom light and re-routing of the cables, also the installation of a 3 core & earth cable and Varilight V-Pro dimmer switch to replace the existing, non LED compatible dimmer switch.

I also decided to fit a Scolmore fused isolator to make dead for maintenance, the finished arrangement is seen below:

V-Pro Dimmer Series Instruction Leaflet 775Download

The modification involves cutting off the controller plugs marked as 1 & 2, this allows the controller to be physically distanced from the base and reconnected using 3 core and earth cable.

The I/R Sensor wire is also cut and extended.

With the controller mounted in a suitable enclosure, a 230v AC relay is added, the relay is connected to the lamp output of the controller, and will be energized/deenergized by the light function button on the remote control.

Using the relay contacts, it is now possible to make the fan light into 2 way switching.

Master Bedroom Fan Wiring DiagramDownload

The 3 core & earth from the dimmer switch is wired across the relay contacts to enable the dimmer switch and remote control to behave as a 2 way switching arrangement with the added benefit of being able to dim the lights from the V-Pro.

Competed project, (lid removed for picture), the maintenance free junction box (JB) to the left of the unit is where the lighting circuit Loop In & Loop Out cables have been pulled back from the original ceiling rose, the supply to the controller is from this JB via the fused isolator.

Electrical & Security

Faulty knightsbridge spike light cable

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I bought from TLC Electrical 6 Knightsbridge GU10SPIKEBK IP65 garden spike lights at £13.25 each and got some odd insulation resistance readings when testing, John Ward and Thomas Nagy (YouTube influencers), have also commented on the problem, so I thought I’d share what I found.

A cable which carries 230v AC is tested at twice its voltage using an insulation resistance tester, this injects 500v DC into the conductors, any issues with conductor insulation will be displayed as a digital reading.

The ideal reading would be >500 Meg Ohms in my meters case, effectively their is no leakage between the conductors under test, BS7671 allow for a pass at 1 Meg Ohm, however, further investigation is recommended if the reading is 20 Meg Ohms or less.

As I knew the age of the garden cabling, its route and connections, I was surprised at finding a less than expected insulation resistance reading which turned out to be the actual cable cable supplied with the spike fitting.

H05RN-F 3 Core 1.0mm2 Ningbo Huashun Electronics

The cable is a 3 core rubberised insulated ands sheathed cable with the identification H05RN-F 3C 1.00mm2 Ningbo Huashun Electronics printed throughout its length.

This image above shows a length of the faulty cable under test, the meter should show >500 not 185.6 Meg Ohms, (this resistance, when connected in parallel with further faulty cables, which also act as resistors, has the effect of significantly reducing the overall resistance/integrity of the circuit).

Ironically, not every fittings cable was affected, but I had lost confidence in the existing cables and replaced all spike light cables with 3 Core Pond Flexible Cable 0.75mm² 3183P Black, £22 for 25m from Wickes, after which all tested >500.

Electrical & Security

Ezviz DB1 /Ring Video Door bell

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Updated 24 September 2021

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Ezviz replaced with Ring Doorbell Pro

Unfortunately the Ezviz had connectivity issues and was as good as useless in remote operation, so I started to look round for an alternative after having discounting a Ring doorbell originally as I couldn’t locally record video and I didn’t want to get tied up in an ongoing contract to allow image retrieval.

Once I had reconciled that paying the monthly fee for the video facility and the other extended features, I went ahead and bout one.

Fitting was very easy, as it was a direct replacement for the Ezviz and the Anthracite cover blended in perfectly with my door and frame.

I also bought a remote chime unit which works very well and the person approaching feature is customizable and very reliable, another plus is that I have linked it to Alexa, this allows announcements to be vocalised and I can call up a picture on my Echo Show.

My Samsung TV also interfaces via Smarthings App to Ring .

Overall I’m really pleased with this doorbell and wouldn’t hesitate to recommend it.

Ezviz Install – Now Removed.

I have wanted a video door bell with two way speech via an App for a while and like most people I’ve looked at the Ring and Nest versions but I wanted to keep my existing doorbell as it interfaces into my alarm and CCTV system and didn’t want to be tied into any form of cloud subscription.

After researching online, the ezviz DB1 seemed to fit the bill as it has internal storage capability, use of existing of wiring and can integrate into my home CCTV system for continuous recording, plus a number of other secondary features which appealed to me.

I bought the ezviz DB1 for £99.99 and a 128Gb Micro SD card for £19.99, both from Amazon.

The kit is very comprehensive and contained everything needed down to the drill bit and screwdriver!

Ezviz Wiring

Wiring couldn’t be simpler, turn off the power to your existing door bell, remove the outside push button and using the same wires, connect it to the DB1.

Inside the door bell, fit a small module across the bell connections, power up the bell transformer* and your all set for the next stage of downloading the App.

Bell Transformer* – My existing door bell transformers output voltage was set to 8vAC and this caused problems with the ezviz DB1 when trying to connect to the App, the transformer also had a 12vAC output which I tried but in my case the only solution which worked, was to buy another bell transformer with a 24vAC output.

The one I bought was from Screwfix and cost £8.95, this transformer will eventually be housed within my consumer unit and so it wasn’t worth getting an enclosure for it.

List of compatible door bells:

My doorbell is a Friedland/Honeywell D113 Surf 2 Note Chime, although its not on the list it work perfectly. The Surf 2 Note is available from TLC Electrical, (as of 17 Feb 2021).

Ezviz App

The ezviz App was downloaded from the App store in my case and needed an account to be set up first which was very quick, following the instructions, the phones camera was used to scan either the QR code on the box or on the DB1 itself and after answering the installation wizards questions the setup was complete.

I chose to use 2.4Ghz rather than 5Ghz as the signal strength was stronger outside where the DB1 is positioned, within the App is a signal strength function to test wireless connectivity.

Configuration

When everything is working correctly a solid blue ring is lit around the bell push button, pressing this causes the internal door bell to chime and the mobile phone will ring as though it is an incoming call, allowing you to accept or decline the call, if you answer the call, two way speech is opened up as well as video.

The DB1 has a presence sensor which can be set so that you are notified when someone approaches the door, the camera will then take a small video which is saved to the internal SD card for viewing via the App.

A schedule can be set in the App making this detection feature very versatile.

The App can also be shared so that other family members can view the DB1 camera or answer calls etc.

The ezviz DB1 does have a cloud subscription service if you chose to use it, however, I have a CCTV system with recording capability and so I simply added the DB1 camera as an input to this system which works very well, even at night due to the DB1 built in infra-red illuminators.

One of the secondary features I mentioned earlier was the ability to add wireless repeater chimes to the DB1.

I bought the CS-CMT-Chime from cctvdirectonline for £41.98, setup was via the ezviz App and it works perfectly in my garden cabin.

17 February 2021 – Relay Interface

My original door bell interfaced into my Pyronix Euro 46 alarm system and Hikvision CCTV, operating the bell push caused the door bell to chime and at the same time and event was logged on the Euro 46 with a push notification with video clip being sent to my mobile, this was the key driver for the DB1 that I retained the door bell chime so I could still have a link into my alarm.

Once the DB1 was all set up and working, I started on interfacing the door bell into the alarm and this is where I met a problem 🙁

The original interface was simply a 12v relay via a rectifier wired across the door bell chime connections, operating the bell push, the relay energized and triggered the Euro 46 alarm input, trying the same configuration, nothing happened when the DB1 was pressed.

I thought that the rectifier might be causing a problem, so I sourced a low power 24AC relay, again this was wired across the door bell chime and again, nothing happened when the DB1 was pressed!

Doing a google search I found that others had discovered the solution to the problem, I’m crediting Sam from the Konnected Forum for the method I have copied and used.

0.2 – 30A SZC23 – NO – AL – CH AC Current Switch

The AC Current switch was bought off eBay for £10.56, the recommendation from Sam was that a larger gauge wire was wrapped around the core about 6 times.

In the picture you can see the transition to the larger gauge current transformer windings, also the terminal connections to the Euro 46 alarm.

The SZC23 – NO – AL – CH AC Current Switch fits perfectly inside the Surf 2 Note door bell after some modification with a Dremel.

Schematic of DB1 Switch installed

Setting Up AC Current Switch

1. One of the supply wire from the transformer which feeds the DB1 is wrapped through the hole in the AC Current Switch and then connected to the DB1.With the DB1 powered up, the RED LED will be lit on the current switch, using a precision screwdriver, carefully adjust the sensitivity be turning adjustment pot until the GREEN LED comes on, then back it off slightly till the GREEN LED goes out. Pressing the DB1 should caused the GREEN LED to momentarily come on before both the RED & GREEN LEDs go out and come back on again, during one press of the DB1, the current switch will trigger twice.

2. Open the Ezviz App to view the DB1 camera and enable the microphone to speak to the DB1, this may cause the current switch to operate, if so, carefully adjust the sensitivity until this action no longer causes the current switch to trigger when accessing using your App, but still triggers when the DB1 is pressed .

3. The DB1 has infra-red LEDs which come on automatically when it gets dark, this increase power draw will trigger the current switch, as per 2 above, make the required adjustments and test operation.

Finished Job 🙂

Electrical & Security

Garden cabin electrics

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This is a follow on from my Dunster House cabin build blog, please note that this work is notifiable under Part P of Building Control Regulations and should only be carried out if competent to do so.

I broke the cabin wiring process into a number of parts, these are:

  • Expected use of the cabin
  • Cabin power demand
  • Submain cable size, type and installation method
  • Existing house supply characteristics
  • Installation method within the cabin

Expected use of the cabin

The cabin is for recreational purposes and will be used throughout the year, this means provision will be needed for TV, lighting , gym equipment , general power both inside and outside of the cabin, exterior lighting, internet and a way to not only heat the cabin in the winter, but to cool it in the summer, all this builds a picture of power demand.

Heating the cabin will take the most power, so I used an online calculator work out heat loss and the energy required to raise the cabin temperature to 20 0 when the outside temperature is 00 , this worked out to be just under 4kW, I then allowed a further 2kW for an external plug-in patio heater should we be sat outside.

It is equally important that the cabin can be cooled for used in the summer, the highest temperature recorded in the cabin so far was over 42.40 on the 19th July 2022, so the installation of an energy efficient Samsung AR18RXFPEWQX heat pump (5kW Cooling/6kW Heating capacity) was an obvious choice with a rated power consumption 1745W during heating.

Fixed loads such as treadmill, fridge and TV within the cabin are calculated to be 750W.

Inside and outside lighting is low energy LED and comprises of a total of 12 x 20W luminaires.

Maximum Demand

Adding the predicted loads together gives a demand of just under 5kW or 21.7 Amps, however, this is not the correct method, applying BS7671 18th Edition On-Site Guide Appendix A for diversity of circuit loadings, the maximum demand based on known and unknown loads after the application of diversity allowance factors and engineering judgement is 36.65Amps (8.43kVA).

The breakdown of this is:

WayCircuitLoad WAmpsDiversity Factor %Demand
1Low Level Sockets20408
2High Level Sockets10004.35Assesed4.35
3External Sockets20408
4Air Conditioning11.510011.5
5Internal Lights6402.4
6External Lights6402.4
Sum36.65
kVA8.43

Submain cable size, type and installation method

British Standards 7671 18th Edition in conjunction with the IET On Site Guide (OSG) and manufactures data sheets will enable all the cable calculations to be undertaken, however, their are a number of cable calculation tools online, this is an example of my cabin calcs, although I did do them manually before verifying the results with the excellent online toolkit from jarsoftelectrical (Cable-Mate) :

Project Name : Cabin Submain with Diversity Allowance

Cable ID / REF number : DB1/Way 1 to DB2

Supply Voltage = 230 Volts
Power factor = 1
Ib – Design current = 36.65 Amps
Protective Device Type = MCB type B (BS EN 60898)
In – Protective Device Rating = 40 Amps

Cable Type : Thermosetting ARMOURED 90°C – Multicore
Length of run of cable = 21 metres
Maximum permissible Voltdrop: 3% (Lighting) = 6.9 volts : Appendix 4
Maximum selected Voltdrop for this calculation = 6.9 volts

Installation Method : Sheathed, armoured or multicore cables direct in the ground:
with added mechanical protection (e.g cable covers).
An installation depth of 0.5 Mtr, A soil thermal resistivity of 2.5 K.m/W
(method D)

Ambient temp = 20 °C
Number of circuits including this one = 1
Length of cable in thermal insulation = none

Apply Correction factors:
From TABLE 4C2 : Cg = 1 (Grouping)
From TABLE 4B2 : Ca = 1 (Ambient temp) – Ground Temperature : 20 °C
From TABLE 52.2 : Ci = 1 (Insulation)
Protective device factor for Buried cables : Cc = 0.9 (Burried direct)
For an installation depth of 0.5 Mtr : TABLE 4B4: Cd = 1.03
For soil thermal resistivity of 2.5 K.m/W : TABLE 4B3: Cs = 1
Protective device factor : Cf = 1

It = tabulated current carrying capacity
It = In / (Cg x Ci x Ca x Cf x Cc x Cs x Cd)
It = 40 / (1 x 1 x 1 x 1 x 0.9 x 1 x 1.03 )
It = 43.15 Amps
From TABLE 4E4A Cable selected = 6 mm²
Current capacity of cable selected = 53 Amps

TABLE 4E4B For 6 mm²: mV/A/m = 7.9
mV/A/m corrected for power factor = mV/A/m x Power Factor = 7.9 x 1 = 7.9

Voltdrop = (mV/A/m x Length x Design current) / 1000
Voltdrop = ( 7.9 x 21 x 36.65 ) / 1000
Voltdrop = 6.08 Volts
(Maximum permissible voltdrop (regulation – 525) = 6.9 Volts)

Calculated Cable size = 6 mm², Minimum Earth conductor size = 6 mm² (Table 54.7)
Maximum Cable Length = 23.8 Metres

My calculated maximum demand is the worst case, it is highly unlikely that the sustained loading on the cabin will exceed my original value of 21.7Amps based on predicted usage, however, I have designed the installation to meet the current regulations and that includes cable sizing, I could have gone for a 10mm2 SWA cable but that would have been over-engineering in my view as all regulatory requirements are within parameters.

Trench contains 6mm 2 core SWA Submain and 1.5mm 3 core SWA external lighting cables, also 2 x 25mm flexible copex all bedded on sand with warning marker tape.
Flexible copex transitions to 25mm conduits, one conduit is spare to the cabin, the other contains 3 x Cat5e network cables and 1 x TV Coaxial Cable.
SWA marshalling cabinet from cabin for external bollards, deck & garden lighting including water features.

Existing house supply characteristics

The supply origin is TN-C-S referred to as PME (Protective Multiple Earthing), in this arrangement the incoming cable is of concentric construction:

Inner Phase conductor, outer conductors Neutral/Protective conductor

Only if certain conditions are met can this type of supply, including earthing, be extended to outbuildings, I therefore opted for a TT supply to the cabin which will have its own independent earth electrode with all cabin circuits protected by RCBOs (Residual Current Circuit Breakers with Overcurrent protection).

With a TT arrangement it is important not to ‘import’ an earth path from the house, therefore the submain SWA terminates into a plastic external enclosure, the TV aerial cable has a galvanic isolator installed to break the shield at the house and the Cat5 internet cables have no connection to earth.

Point of entry and exit for all cables, earth electrode connection point is also visible.
TV aerial cable Galvanic Isolator.
Three patch panel ports dedicated to the cabin, pink leads denote POE.

Installation method within the cabin

Wood expands and contracts with humidity by up to 12mm in my case, therefore the wiring method must be able to accommodate this movement, I chose to use Univolt 100mm x 50mm dado trunking installed all around the base of the cabin and to the consumer unit, from this trunking 20mm heavy duty PVC conduit is taken to lighting and high level sockets, this gives me total flexibility to add to the wiring system if needed.

To allow for expansion, I have used a combination of lubricated slip couplings for 20mm conduit joints and flexible conduit for movement transitions where appropriate.

The trunking is capable of having a partition piece inserted to make a segregated trunking compartment, this I have used for data and TV cables.

Cabin DB2, trunking has lighting switches for gym lights and dartboard, also power energy monitor and separate control for treadmill supply
The surface mounted back box with blanking plate under the consumer unit houses the Quinetic external lighting receiver.
D Line metal fire clips from Toolstation have been used to give additional support to the20mm conduit to prevent premature collapse in the event of a fire.
Tado Smart AC controller remotely operates the Air Conditioning and monitors cabin temperature.
Non Maintained emergency light at low level by the exit door should the lighting power fail to the cabin, to the side of the light is the test key and local fusing.
isigns did a great job of engraving my grid switches, this now removes any confusion as to what the switches do.
8 lighting panels were used and I’m really pleased with the light output and uniformity of coverage.
Sperate conduits for data and power, the TP Link Access Point is POE.
Heat Pump, I had this professionally installed (long story!)
Tado graph showing the temperature rise after just a short period of the Air Conditioning being set to heat.

The cabin consumer unit has 6 RCBO protected ways these are for:

  • Way 1. Low level dado trunking socket outlets (B20)
  • Way 2. High level sockets via conduit (B20)
  • Way 3. External IP rated double sockets (B20)
  • Way 4. Air Conditioning unit (B16)
  • Way 5. Internal lighting including emergency light (B6)
  • Way 6. External lighting and water features (B6)

The cabin area is 29.25m2 and the OSG Table H2.1 final circuits to sockets outlets are Type A3, Radial using 2.5mm2 singles.

Low level dado trunking has 13 double sockets, the vast majority are not used but as the cost per socket is less than £5 it was worth doing, the high level socket circuit only has 1 double socket and one single socket so I’ve assed the maximum load to be 1000w as these sockets are dedicated to low wattage chargers and a TV it is highly unlikely this will be exceeded, especially considering the number for dado sockets 🙂

I have installed 3 double IP rated external sockets as a separate Type 3 Radial circuit.

Internal lighting cables are all 1.5mm2 singles, external lighting and water feature cables are 1.5mm2 SWA.

Update

Having used the cabin for a year, one of the things I didn’t install at the time was a means of two way switching the cabins outside lights on or off, I thought the external security light sensors on the house would bring the house mounted lights on if someone left the cabin at night, unfortunately this wasn’t the case, so the first few steps out of the cabin were in pitch darkness, which is less than ideal.

The solution came with Quinetic switches from TLC, these are quite amazing as the switches need NO POWER, they internally generate enough energy to transmit to a receiver which could be up to 30m away.

Grid switch module from Quinetic

The above picture shows a two gang switch plate, originally this was only a single gang switch for the utility light by the back door, changing this to a grid switch allowed me to have the first switch as the utility light and the second switch as a Quinetic module remotely and wirelessly turning on and off the external cabin lights.

In a previous picture of the cabins four gang switch, the external lighting switch is also a Quinetic module, both paired to a single receiver operating the lights, I also have a keyfob paired to the receiver giving me maximum flexibility in operating the lights.

This modification was very easy to do with no mess, unlike the traditional method of hardwiring and cable chases.

Electrical & Security

Intruder Alarm Circuit Test Box

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I thought I’d build a test box which will simulate the three circuit conditions of an intruder detection system (IDS), these being:

  • Circuit Tamper
  • Alarm Condition
  • Circuit Healthy or Closed (non alarm condition)

The purpose was to confirm and test the ’cause & effect’ programming of a Pyronix Euro 46 panel , the Euro 46 remote Upload/Download Software allows for logic gates to be configured, so the system ended up being very versatile.

The above picture shows the Euro 46, Keypads, Zone Expansion, Output and Wireless modules set up for testing using the multiswitch test box, the alarm system is communicating with the Pyronix Cloud server via a LAN interface, cloud configuration also allows seamless integration with the Hikvision CCTV system.

The Euro 46 has several detection circuit configurations, I chose the common value for a Double End Of Line resistor system of a 2k2 and 4k7 Ohms.

At the detection input a healthy or closed circuit, would measure a resistance value of 2k2 Ohms, if the value either exceeded or fell below this by a defined margin, the alarm panel would see this as a tamper condition, and alarm condition would present a value of 4k7 Ohms, the test box achieved the three conditions listed using the following diagram:

The above circuit presents to panel with slightly more resistance than 2k2 when healthy, however, as its within the parameters, the panel see’s this as closed with no faults.

The completed unit was built using 30 switches and I utilised an old piece of trunking to fit them in:

The circuit description label temporarily sticks over the laminated switch backing so I can fully program and test the wired circuits before installation in the future, one element I can’t test is the wireless aspect which forms a a large part of this system.

Electrical & Security

BRK Smoke Alarm Relay Interface

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I have a number of BRK Smoke and Heat detectors which are interlinked to all sound on activation of any detector, I needed a way of linking the detectors to my house alarm which in turn would alert me on the mobile app.

A quick Google search flags a BRK RM4 relay interface which is triggered by the interconnect wire, the problem is they are only for the US market and work at 120v AC, this was confirmed with a phone call to the UK BRK representative.

RM4 InstructionDownload

I decided to take a punt and bought a RM4 from a US vendor, this took ages as a large number of seller just wouldn’t entertain shipping to the UK.

The moment the RM4 arrived, it was cut open 🙂

After checking the component data sheets the only parts which needed upgrading were the 2.2uF capacitor from 50v to 250v and the relay from 120v AC to 240v AC (part 369-337: G2R-2 230v).

Before swapping the parts I set up a ‘rough and ready’ test rig using a variostat to provide 110v AC to the RM4, a clamp meter was used to measure RM4 consumption and a 9v battery ready to place a voltage on the interconnect wire simulating an alarm condition, this worked fine.

After exchanging the capacitor and relay the RM4 was back on the rig and the supply voltage gradually increased to 240v AC while keeping a close eye on the current consumption which slightly increased from 2.8mA to 3.3mA.

The interface works as expected and the relay energises when a voltage is on the interconnect wire, it must be noted that the interface requires a supply voltage for it to work, the relay will not work in a power outage.

Sorry, bit of a messy picture, the RM4 is powered via the Rheostat with a ‘clamp on’ ammeter monitoring current draw and multimeter displaying the input voltage to the RM4, the PP3 9v battery was to simulate an trigger on the ‘Interconnect’ signal wire.

The RM4 wires are coloured for the US market and required sleeving with UK colours:

  • RM4 Relay White wire = UK Blue Neutral
  • RM4 Relay Black wire = UK Brown Live
  • RM4 Relay Orange wire = UK BRK White Interconnect