Home automation: Installing a relay into a consumer unit

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Hi,

I am looking for a solution to a problem for controlling garden lights and a pond pump with OpenRemote - a home automation controller.

I am in favour of installing two 12A 240 VAC relays, that have a built in web server that can be controlled by OpenRemote.

I plan to install two appropriately sized RCBOs into the pond and lighting circuit and connect these to the relay's load circuit. The relay's control circuit would then be connected to my Ethernet switch (PoE).

Is this type of installation covered by and allowed under Part-P, or should I look at buying a serperate DIN rail enclose such as this, leaving the RCBOs in the CU and the wiring from the CU to the enclosure?

Any advise on the subject will be gratefully received.

Many thanks

W.
 
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Most residential CU's dont have "spare" sections of din rail that you can use to install random din rail parts. They usually have busbars and things in the way.

They also have a narrow opening in the front, which your relay/computer wouldnt fit thru.

Much hackery would ensue if you tried to fit those inside a normal CU enclosure, so i'd suggest you get yourself a second box to hold them.
 
There is no simple answer. A consumer unit is a type tested distribution unit some where around 1989 they replaced the old fuse box. There are some rules about domestic premises but I am not sure if it's dependent on the skill of the occupant or not.

Adding anything non approved into a consumer unit changes it from a consumer unit to a distribution unit.

Part P is law but BS7671 is not and it is very hard to work out what the law requires. The wording of Part P is very poor and so many items are left for the courts to decide.

In the main the courts will only get involved with a death and even then for a home owner rather and tenant they don't seem to be that worried.

So in real terms if you build it and nothing goes wrong then no problems if something does go wrong then HSE may decide to investigate and if they start a court case then we will find the answer.

So if one follows the general rules it is unlikely you would be prosecuted. Looking at the Ethernet Relay Module I fail to see how this could be mounted in a DIN rail consumer unit and keep all live parts where they can't be touched I would not consider them as a suitable enclosure but without careful measurement it would be hard to tell.

It has come up in the past with Radio Hams who have to pass their RAE to do the hobby and often make home brew equipment which is the whole idea. But passing the RAE shows they have the level of skill required. A home brew enthusiast may make himself a temperature controller but in this case he has no qualification so show he knows how to do it safely.

This is a duel edged sword as with an accident the ham should have known better but the home brew guy should not be playing with things beyond his knowledge.

So it's for the court to decide.
 
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For simple ON - OFF control of mains voltage I use DIN rail mounted relay sockets in a consumer unit housing.



The space under the relay can be filled with plug in indicator LEDs to show the state of the relay.

The relays I use are Finder but other compatible makes can be found

For single pole change over relay 40.61 base 95.83

For two pole change over relay 40.52 base 95.85
 
Would installing something like this in a consumer unit be coded?
I was under the impression that not even door bell transformers, fitted in to CU enclosures are considered good practise!
 
The mains supply is from a 3 amp fuse in a plug or a FCU and thus the enclosure is not a consumer unit.

I agree that bell transformers and other similar items should NOT be in the consumer unit.
 
Why on earth would anybody want to control pond equipment and lights via a web browser?
 
The mains supply is from a 3 amp fuse in a plug or a FCU and thus the enclosure is not a consumer unit.

I agree that bell transformers and other similar items should NOT be in the consumer unit.

Hi bernard, I was referring to the OPs suggestions.
Impressed with your set-up.
 
Is this type of installation covered by and allowed under Part-P, or should I look at buying a serperate DIN rail enclose.
Use a separate enclosure.

Feed it via a double pole isolator so that it can be fully isolated when there is a fault in the pond pump or the control system.
 
In my house I am sure there would be no issue in having a box with din rail be the original designed as a consumer unit or for anything else containing relays to control any equipment.

However if I was putting in some equipment in some one else's house then I would need to consider what the occupants may try to do. In the same way as if fitting it in any factory I would have to ensure some cover is in place which requires a tool to be removed before anyone can get access to live parts.

So I would want to provide a degree of protection of at least IPXXD or IP4X be it a horizontal top surface or not. If the lid of the consumer unit will lock down then fair enough and if you can see through the lid even better but the gap between the din rail and the hole provided for the MCB's to poke out of is to me not enough to mount items without have access to live parts.

OK I realise to the regs IPXXB or IP2X is enough at the front but personally I would still want IPXXD or IP4X.

I again don't personally care what the Part P or BS7671 says I want it to be safe. So a simple box like this
EKM-Metering-Watertight-Enclosure-Kit-Exterior-IP65.png
to me is far more suitable as you have the distance between cover and din rail and no access for anyone to poke something in.

I would cut a perspex sheet to fit inside the box with holes where access was required for example top of PLC to plug in PC and over socket to power PC and also any reset buttons so I could leave door open without there being a problem.

I tried to arrange it with low voltage at top and extra low voltage at bottom so I could reduce size of perspex sheet. OK some times it went wrong I remember ordering two contactors for the emergency stop with 24 volt coils and spaced everything out ready using some 230 volt ones. When the contactors arrived they were taller than 230 volt ones.

But never the less when the HSE visited I had no problems with those boxes in spite of the contactor poking through leaving doors open while altering PLC program.

Down to basics the Part P law means a house has to be as safe as a factory and replaces factories act and offices shops and railway premises act in the home.
 

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