Consumer Units - RCCD Connections


Postby EdF » Tue Apr 22, 2008 8:00 am

I've recently installed two different split load consumer units, one in my house and one in an oubuilding conversion. Are there some circuits which cannot be connected to the RCCD side and what are they? I found that a simple lighting circuit tripped out and had to be moved to the non-RCCD side, likewise a long-established circuit to other outbuildings on the other consumer unit. I'm pretty good at wiring and am confident there were no mistakes made. Thanks for any replies..
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Postby ericmark » Tue Apr 22, 2008 1:03 pm

By the 1st July 2008 all new work will require RCD's or RCBO's to be fitted to near everything. Outbuilding can be more of a problem where extra earth rods and minimum earth cables sizes can complicate things and really one needs to carefully read the regulations with respect to type of supply. TT, TN-S etc. Split load consumer units now come in many different versions some with two and some with three neutral bars the non RCD protected section would under the new regulations be populated with RCBO's The rules are mainly to do with safety in that when an RCD trips due to an fault with something plugged in it should not trip the lights in the same area. Easy way is to use all RCBO's but with careful splitting you can get away with two RCD's in most cases. Fire alarms can't go on same circuit as sockets so these would need RCBO's and caravans must switch all live circuits i.e. neutral as well as line so can't use most RCBO's and have to use RCD's where surface wiring is used you may not need an RCD but the common practice of moving problem circuits off the RCD protection will stop and only option is to split the circuits so each has its own RCBO rather then all being protected by a single device. About the only circuit without RCD protection would be where a SWA cable feeds a garage etc. Where the RCD would be at garage side rather than house side. There is one big problem with DIY in that the meters required to test the installation is OK are so expensive around £750 a set. This means faults which would be found and cured by a professional are near impossible to trace for DIY
ericmark

Postby EdF » Tue Apr 22, 2008 5:53 pm

Arrghhh, I hate TLA's !! Many thanks for the reply. What I meant to write was, 'are there any circuits which won't work on the RCCD side of a consumer unit?' Although I can't think why, I couldn't understand why those two circuits would only work on the non-RCCD side.. As I wrote, one was a very simple circuit with a couple of temporary lights off a temporary socket.. I do have a professional electrician next door, so I'm going to get him to do the testing on completion of the house. It worried me slightly when he asked me if I could wire up two-way lights, as he couldn't remember...

TLA - three letter abbreviations!
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Postby ericmark » Tue Apr 22, 2008 10:58 pm

All circuits can have RCD protection in a normal house. The exceptions are unlikely to be found in a normal house. As to two way lighting and central heating wiring they are only found in that configuration in domestic electrics so I can understand industrial electricians forgetting how.
ericmark

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