I used two smaller units, both RCDed, with split tails from the meter. Worked out cheaper than a split unit as they were on offer at B&Q at the time.
Dodgy stuff - lights, outdoors, the bath, etc on one, whereas upstairs rings, kitchen and stuff unlikely to trip unless there is a real fault on the other.
I would only buy MK Sentry products for this, although Hager is fairly respectable as well.
You need to protect any sockets that could be used for portable equipment outdoors. This could be done by putting the entire ground floor ring circuit downstream of the RCD. It is best to have the lighting upstream of the RCD. You could run a separate radial circuit just for the freezer from the CU, upstream of the RCD. I did this and also used MK non-standard plug and socket to prevent anything else being plugged in to the outlet. These have a T-shaped earth pin to achieve that.
.andy
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Work I'm having done soon looks like it will require me to sort out my consumer unit, presently an old 5-way Wylex with cartridge fuses. I probably need more circuits, and RCD protection on some of them.
I see that split units are available, can anybody recommend a particular one the have had success with (or ones to avoid)?
What are the thoughts on which circuits to protect with the RCD? I can see that, for instance, if I plug the lawnmower into the kitchen socket, the downstairs ring could be a candidate.The garage naturally, and the new Airbath which is prompting the work. OTOH coming home to a dripping freezer because of a spurious trip is not a nice image.
Chris
On Fri, 02 Jul 2004 20:29:01 GMT, Chris J Dixon strung together this:
MK Sentry, Square D or Hager Vision are recommended. Avoid Legrand, Tenby, Vynckier\GE\Sector and Moeller.
Anything that can be reasonably expected to supply power to portable equipment being used outdoors. So all downstairs sockets, or Just outside sockets located around the house in convenient locations with their own RCDs or some mixture of the above two.
A common workaround for that problem is to wire a radial circuit for the fridge\freezer circuit. If you used outdoor sockets with RCD protection then no indoor sockets would need RCD protection. You could also use sockets with RCD protection built in at convenient points throughout the inside of the house and negate the neded for the RCD in the CU altogether.
MK are good but pricey ... although they do have some offers on in some wholesalers and B&Q Warehouse. Tenby are much cheaper and reasonable quality.
Rick
This does assume the OP is not on a TT system (typically power supplied via overhead cables) - in which he would need RCD protection on all the circuits.
True, but AIUI it's then a 100mA time delay type covering everything followed by a 30mA type for the circuits requiring closer protection....
.andy
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On Fri, 02 Jul 2004 23:28:40 +0100, Andy Hall strung together this:
Yes, forgot to add that disclaimer. Basically, if you're on a TT system the only major difference is that you need an earth spike and instead of the main switch you install a 100mA RCD. The regulation regarding the RCD protection remains the same, the protection for socket circuits supplying outdoor equipment needs to be 30mA whether it's TT, PME, T-N-CS or otherwise.
Not a problem for me.
Chris
Thanks for that bit of info, we will soon be moving to a place with just that ! It will be useful to remember. Cheers JohnB.
I'm on a TT system, and faced with a similar problem. The RCD in my CU is
30mA and I need to rewire my garage and an outside shed so I was thinking of supplying both from the non RCD side of the main CU, and installing separate CUs with their own 30mA RCD in each building. Does this sound acceptable?On Sat, 3 Jul 2004 10:20:52 +0100, "Eco Warrior" strung together this:
You shouldn't have a non-RCD side of the CU. All circuits on a TT system should be protected by a 100mA RCD, and additional 30mA protection should be provided for the sockets that will provide power to the outdoor equipment. Other than that, installing the 30mA RCDs in the outbuildings sounds fine.
What do you mean by TT ~ I'm supplied by overhead lines (only about 5 & on t'graph poles) & have experienced the odd spurious trip since changing over to a split load CU. Do you think that I need to replace the 30mA RCD with a
100mA one & would this resolve the problem.The previous wired fuseboard was protected by a separate 30mA RCD & never tripped out.
Thanks Mike
On Sat, 3 Jul 2004 09:59:54 +0000 (UTC), "mj" strung together this:
TT is the earthing arrangements of the supply. If you're on TT your earth will be provided by a spike\rod in the ground outside.
When yoou say split load I assume you mean you have a time delay split load. i.e. ALL circuits are protected by a 100mA RCD and additional
30mA RCD protection should be provided for all sockets reasonably expected to supply power to outdoor equipment.How many times do I have to repeat this today?
Alternatively you could go for the type of setup I will install shortly: Two CUs fed from a master switch, one protected by a 100mA RCD (no time delay) and the other protected by a 30mA one. By not having the 30mA RCD downstream of the 100mA one, you avoid the discrimination problem that the time delay would normally be needed to resolve.
I would not want lights on an RCD. Death by electrocution from lighting circuit is virtually non existent, whereas injury and death from lighting failure is known.
Also I would not want lights on a type B MCB. In some installs regular MCB popping results. Type C would be better. I wont mention fuses :)
Outdoor kit is a reliability liability, and so is better not on the same RCD as anything indoors.
wouldnt that be everything? :)
Regards, NT
Can't answer that one ~ Don't know where the earth goes ~ The Neutral is connected to the armouring of the incoming cable though
All I have is a split consumer unit with a 100A main switch (not RCD) covering all trips & a 30mA rcd covering the power circuits. there is no other units between this and the meter & main fuse
dunno :)
On Sat, 03 Jul 2004 13:24:22 GMT, Chris J Dixon strung together this:
Not really, although it does help. You can extend the cables inside the CU with butt crimps.
On Sat, 3 Jul 2004 12:18:53 +0000 (UTC), "mj" strung together this:
That sounds more like PME or T-N-CS in that case.
That sounds OK. In answer to your original question of changing the 30mA RCD to a
100mA one then no, you can't. The 30mA RCD is needed to protect the sockets at 30mA and no more. Depending on what make your fuse board is you could change the 30mA RCD for a standard main switch and fit individual RCBOs to each socket circuit and anything else requiring RCD protection. This would then keep any tripping localised to one circuit only.
OK ~ will look into it some more
Cheers & have a good weekend!
Mike
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