Completeley OT !!!

Someone on this NG will know this!!

I'm fitting a shower and have bought an RCCB to fit - silly me I thought it would come with instructions so did not ask at the shop how to fit.

its 2pol, and has 4 connections, on metering these out it switches 1 to 2 and 3 to 4

What needs to be connected, is it L and N. i.e. does it sense between these two poles or should it be live and earth ( although this does not make sense to break continuity of earth. ( I seem to remember circuit breakers sense current to earth)

The last domestic wiring I studied was in College in 1989! I can do a mean ring main or spur but I fall down after that

Help! and thanks in advance

RCB you mean ? Or what used to be called an ELCB?

2 Pole matey!

It's a residual current device, it monitors the earth loop for a current leakage via the actual earth on the consumer unit (if it is a CU mounted unit) use the unit to switch (via it's own inegral knock off circuit) L&N. The earth is monitored by a flying lead to the earth bar. They are available in differing mA ratings for differing uses/environments. You simply connect the live onto one pole, then the neutral to the other

No bother ! If you need a bit more in depth, just hit me back!

Nige (I.eng)

in article c54bi5$f84$ snipped-for-privacy@newsg2.svr.pol.co.uk, StaffBull at snipped-for-privacy@staffbull.net wrote on 8/4/04 9:12 pm:

Bruce says he's take it back. It should have some instructions with it.

I got it from an electrical factors shop ( where the sparkies get their stuff) so they probably thought I knew what I was doing!!!

Ah well, the insurance is paid up.

1>2 live 3>4 N, they sense any difference in the currents and if the difference is more than 30 ma or so they trip, usually fitted in between the meter and the fusebox so as to cover the whole installation rather than just one item. steve the grease >

Domestic RCB units do not monitor earth at all. It monitors the Live and Neutral phases, and the difference between them. More than 30ma difference and it pulls the trip.

Alex

Wel, not wanting to argue off topic but that's wrong. RCD's monitor earth leakage in one of two ways. One way is how you mentioned, this is still monitoring for earth leakage between phase & neutral. These have just the 2 pole connections. The one I have is linked direct to the earth bar. Both ways are monitoring for earth leakage..

Cheers

Nige

We are arguing the difference here between ELCB and RCD now ? I would argue that you are describing an ELCB, where others are describing RCDs/

Steve

All doene !

L & N pass through the RCCB and the earth bypasses the RCCB and straight to the shower.

Theory of operation is : if no fault condition exists to earth from either L or N poles then the current in both conductors is equal and the RCCB is happy to stay on! If a fault condition arises between either pole and earth then there will be a current imbalance between the two conductors, and this will induce a flux into and iron core in the RCCB this in turn switches it off.

Simple after all.

I feel better now I understand it, I dont like trusting anything I dont understand - especially when it can pull 40A under a jet of water!!!!!!!

Thanks for all your help.