Homemade Electrical Equipment

[i_am_fubar]

I know the phrase 'home made' brings to mind endless dodgy cudgels. However, in this instance, I use it to describe professionally designed and manufactured one off prototypes, not yet certified to any standard but designed to suit.

I have plans for to make a homemade home automation controller. I know you need to conform to various BS to wire devices permanently into domestic mains. However, it there a way of interfacing into mains control via approved equipment?

for example, a mains relay panel that can switch various T&E circuits from 12v DC inputs (as supplied by homemade equipment).

What difference in situation do you get between equipment on a plug, equipment wired into a fused spur, and equipment wired directly into a ring / radial / spur?

Cheers,
Fubar.

 

[JohnW2]

I know the phrase 'home made' brings to mind endless dodgy cudgels. However, in this instance, I use it to describe professionally designed and manufactured one off prototypes, not yet certified to any standard but designed to suit. ... I have plans for to make a homemade home automation controller. I know you need to conform to various BS to wire devices permanently into domestic mains. However, it there a way of interfacing into mains control via approved equipment? ... for example, a mains relay panel that can switch various T&E circuits from 12v DC inputs (as supplied by homemade equipment). ...
What difference in situation do you get between equipment on a plug, equipment wired into a fused spur, and equipment wired directly into a ring / radial / spur?

As far as I am aware, there is a lot less 'regulation' that you might imagine. Provided that your equipment is safe (particularly in the way in interfaces with fixed wiring etc.), satisfactorily designed and 'fit for purpose', there's probably not too much to worry about.

One issue is that any sort of 'bespoke' electrical equipment or control systems can be a significant 'negative' issue if/when you come to sell the house - since no-one other than yourself may understand it well enough to maintain it. At the very least, you would need to produce comprehensive documentation but, even then, many an electrician may be uncomfortable working on a 'unique'installation.

Kind Regards, John

 

[ricicle]

It might be a good idea to inform your house insurance company as well if this will be a permanent set-up.

 

[JohnW2]

It might be a good idea to inform your house insurance company as well if this will be a permanent set-up.

I suppose that's strictly true, but it would probably open up a can of worms, not the least because the insurance company almost certainly would not 'understand', and would therefore probably just react in a fairly draconian fashion, rather than trying to develop some understanding!

Kind Regards, John

 

[ricicle]

It might be a good idea to inform your house insurance company as well if this will be a permanent set-up.

I suppose that's strictly true, but it would probably open up a can of worms, not the least because the insurance company almost certainly would not 'understand', and would therefore probably just react in a fairly draconian fashion, rather than trying to develop some understanding!

Kind Regards, John

Probably true as the risk of an incident from a competently installed set-up is vanishingly small. In reality the risk is no greater than any competent work on the mains wiring itself I would have thought. Probably the same response if you contacted them to say I have done work on my electrical installation as I am competent but not qualified ?

 

[JohnW2]

Probably true as the risk of an incident from a competently installed set-up is vanishingly small. In reality the risk is no greater than any competent work on the mains wiring itself I would have thought.

Exactly - but I do seriously doubt that most insurers would understand or think like that. The moment they heard mention of 'home-made electrical equipment', they would probably just add a few zeros on the end of the premium and think no more deeply than that!

Kind Regards, John

 

[ban-all-sheds]

I have plans for to make a homemade home automation controller.

Because you want to build it, or because you think you have to?

I know you need to conform to various BS to wire devices permanently into domestic mains. However, it there a way of interfacing into mains control via approved equipment?

Z-Wave controllers/adapters?

Or have you got space for a very large CU? Because if you have:

for example, a mains relay panel that can switch various T&E circuits from 12v DC inputs (as supplied by homemade equipment).

PLC, DIN-rail mounted contactors...?

 

[ericmark]

There is a slightly different set of rules when under the supervision of a skilled or instructed person and so to install something home made in ones own house is different to doing the same in some one else's house.

My dad was an electrical engineer, my father-in-law was an electrical engineer, son-in-law was an electrical engineer and my so is an electrical engineer. Oh and so am I. As a result family houses have had some non standard gear installed but I go to do work on my mother's house and scratch my head trying to work out what my dad had done. This is a major problem we all think we will remember but we don't.

So I would say when doing work think about what happens when you go to work abroad for 18 months and your wife needs to get something repaired. Even with standard equipment if I fit a PLC to control my central heating the only person I know who could fix it is my son. Even then he would be looking for my PC with names on the program not up-loading from PLC.

The other problem is the jobs worth. I was looking at some really neat panel 13A sockets for the caravan. OK I would fit a backing box but if tested by a third party would he pass it?

 

[Robin0577]

I come across this issue in theatre and TV studio installations all the time, all manner of custom devices installed to control house lights, cue lights, "on air" signs, etc.
Most of the time they've been quite well done, so well in fact that by the time they need any repairs, the folks who installed them have long moved on/retired/died, leaving no trace of a diagram behind!

 

[JohnW2]

...Probably the same response if you contacted them to say I have done work on my electrical installation as I am competent but not qualified ?

I've just noticed that you appear rto have slipped this in after I replied! Yes, I agree ... I strongly suspect that if anyone volunteered such information to an insurer, there would be a fair chance that their response would, again, be fairly 'draconian'. In a sense, it's a pity, because it does nothing to encourage people to be complete in their 'disclosures' to insurance companies.

Kind Regards, John

 

[crystal ball]

I know the phrase 'home made' brings to mind endless dodgy cudgels. However, in this instance, I use it to describe professionally designed and manufactured one off prototypes, not yet certified to any standard but designed to suit.

I have plans for to make a homemade home automation controller. I know you need to conform to various BS to wire devices permanently into domestic mains. However, it there a way of interfacing into mains control via approved equipment?

for example, a mains relay panel that can switch various T&E circuits from 12v DC inputs (as supplied by homemade equipment).

What difference in situation do you get between equipment on a plug, equipment wired into a fused spur, and equipment wired directly into a ring / radial / spur?

Cheers,
Fubar.

This sounds very similar to Electratech, a heating control system installed by NORWEB in the 80s/90s

 

[efficiencyman]

I am sure that we will see far more of these type of control systems in the future. There are so many remote control switching systems available now and with the ability to control systems over the web. With over a million raspberry pie units sold, I shall watch this thread with interest of how the guidance will develop, on the mains interface connections etc.

 

[i_am_fubar]

Sheds, want all the way. With luck, I can use the installs as a test platform for furthering development to a commercial product.

Like eric, I am an electrical engineer myself and have designed various bits of mains equipment for CE certification and sale globally. So I have no concern about the safety of such a device.

As people are pointing out, insurance is probably the number 1 reason this could be a bad idea.

I have no fixed plans for exactly what I want yet, but I am envisioning a DIN rail cabinet loaded up with COTS relays / contractors with a small embedded controller / PC.

Interesting responses though, cheers guys.

Fubar.

 

[bernardgreen]

The mistake that is most common in DIY control systems is in-adequate separation between control circuits and mains voltage circuits.

Provided there is adequate separation and the mains wiring complies to BS7671 and other requirements a DIY system should be acceptable.

Adequate separation ( in my experience ) is a break down voltage greater than 2000 volts for a minute. At least 4 mm tracking distance between metal parts and prefereable 6 mm.

Not all mains rated mechanical relays and opto isolated solid state switches provide this level of separation.

That said it can be difficult to prove to a non technical insurance person that a system is safe when built by a DIYer to a DIY design.

 

[stillp]

The mistake that is most common in DIY control systems is in-adequate separation between control circuits and mains voltage circuits.

Provided there is adequate separation and the mains wiring complies to BS7671 and other requirements a DIY system should be acceptable.

Adequate separation ( in my experience ) is a break down voltage greater than 2000 volts for a minute. At least 4 mm tracking distance between metal parts and prefereable 6 mm.

Not all mains rated mechanical relays and opto isolated solid state switches provide this level of separation.

That said it can be difficult to prove to a non technical insurance person that a system is safe when built by a DIYer to a DIY design.

In my experience an impulse test is far more onerous than 2kV for a minute Bernard.
I think the only way to demonstrate to an isurer or anyone else that the equipment is safe will be to test to an appropriate BS EN; 60950 and 61010 would be a start, although there are some specialist standards for home automation equipment.