Help! RCD Keeps tripping on new wiring

[Seri]

First of all, it's ultimately possible that I've done something excessively stupid to cause my problems (I say this so that no-one will rule out any of the obvious suggestions).

I've just started rewiring my house today, I've ran a new set of tails to my new consumer unit, and have another set of tails to my old consumer unit. The new consumer unit is split load.

Just to test things out, I've wired a single socket to the new CU on the RCD protected side. If I plug anything what so ever into the socket I've wired in then the RCD trips the moment the item is turned on.

I also had another consumer unit with RCD which I was going to use to protect the external sockets. So I removed the RCD from that and used it to replace the RCD in the installed consumer unit. The RCD's are exactly the same model number. I get exactly the same response, immediate trip when a device asks for power.

I rewired the socket over to the non RCD side of the consumer unit and it works fine.

The socket is wired as a direct spur straight from the RCD rather than as a loop (it's only for testing).

The consumer unit and the RCDs are Contactum.

Can anyone make any suggestions? I'm highly doubtful that I've been given two duff RCDs but I can't think of anything else...

Help! Please?

Thanks

Seri

[Tony Bryer]

Just to ask the obvious (not meaning to insult you) you have taken the N from the socket through the RCD and not straight to a neutral busbar ??

[Seri]

No insult what so ever, I know it's likely to be something silly like that.

Just checked and the neutral from the socket is wired into the shared neutral bus bar, only the live is wired directly into the MCB.

I should say that this is my first time doing anything like this (as if that probably wasn't patently obvious already).

Thanks anyway though

Seri

"Tony Bryer" wrote in message news: [e-mail]... | In article , Seri | wrote: | > Just to test things out, I've wired a single socket to the new CU | > on the RCD protected side. | > If I plug anything what so ever into the socket I've wired in then | > the RCD trips the moment the item is turned on. | | Just to ask the obvious (not meaning to insult you) you have taken | the N from the socket through the RCD and not straight to a neutral | busbar ?? | | -- | Tony Bryer SDA UK 'Software to build on'

| Free SEDBUK boiler database browser ||

[Lurch]

On Sat, 03 Apr 2004 19:21:17 GMT, in uk.d-i-y "Seri" strung together this:

Have you got the neutral in the right busbar?

Are you sure it's not the device you're plugging in that's at fault. Most people tend to accuse RCD's of being faulty if they trip.

You mean hung off the bottom of thr RCD with no MCB?

[Andy Hall]

.... and removed the link if there are two neutral bus bars......

.andy

To email, substitute .nospam with .gl

[Lurch]

On Sat, 03 Apr 2004 19:42:54 GMT, in uk.d-i-y "Seri" strung together this:

Shared? You mean as in the one that the RCD feed, (top connections), is taken from or the one that the load of the RCD connects to, i.e. the one connected to the bottom of the RCD. It should be this one.

I've seen so called pros scratching their heads over this sort of simple quandry!

[Seri]

Oh, remove the link? There are two neutral bus bars, the current flow of neutral seems to be:

Neutral tail into top of master breaker Neutral link from bottom of master breaker to first neutral bus bar Neutral link from first bus bar into the top of the RCD Neutral link from bottom of RCD into second neutral bus bar

After following all that through I noticed that my neutral from the socket was into the first neutral bus bar and not the second. I just shifted it over and voila, it all works... something so simple and I feel so stupid.

Oh well, you live and learn.

Thanks for all your help, it was EXTREMELY appreciated as it was driving me nuts and I couldn't see what was wrong.

A big thanks

Seri

| >Just to ask the obvious (not meaning to insult you) you have taken | >the N from the socket through the RCD and not straight to a neutral | >busbar ?? | . | | .... and removed the link if there are two neutral bus bars...... | | | | | .andy | | To email, substitute .nospam with .gl

[Tony Bryer]

How do think I knew

[Andy Hall]

It's very easily done. I've got a T-shirt.... :-)

.andy

To email, substitute .nospam with .gl

[Dave Stanton]

On

Caught me out at least once, in front of a customer as well, DOH.

Dave

[The Natural Philosopher]

:-)

But you are a far better electrician for having got it wrong, aksed, understood, and fixed it, than if you had blindly followed instructions without ever woking out what where or why...

[Lurch]

On Sun, 04 Apr 2004 08:46:04 +0100, in uk.d-i-y The Natural Philosopher strung together this:

Quite right, I see too many droids mindlessly cobbling things together without noticing what they're doing wrong or why they're even there. I've just been to look at a job where someone else has done a test, they appear to have missed most of the dangerous\dodgy bits and what they've written down is either wrong or irrelevant\too vague to be any use. Funnily enough they missed the bits they just put in incorrectly!

[Owain]

"Seri" wrote | Neutral link from bottom of RCD into second neutral bus bar | After following all that through I noticed that my neutral | from the socket was into the first neutral bus bar and not | the second. | I just shifted it over and voila, it all works...

It is good practice to have the connections on the neutral and earth bars in the same order as the circuits appear at the MCBs. If you get into that habit you're less likely to put a neutral on the wrong bar.

Owain

[Seri]

Funilly enough, it was doing precisely this that caused my problems in the first place!

It's a split load consumer unit but I had to manually split the main bus bar, because I wanted most circuits to be RCD protected I split it so that MCBs 1-5 were non RCD protected and 6-12 were.

The ring I wired in was for MCB 6 (RCD protected).

The Neutral bar for the non RCD side was for MCBs 1-6.

Hence how I made my mistake... Wired the new circuit into MCB 6, Earth Bus Bar Point 6, Neutral Bus Bar Point 6...

Does mean now that I'll end up with some empty points on the non RCD Neutral Bus and some points that are doubled up on the RCD protected side now...

Still, at least it's all working, I completed the ring and then used it to plug the power tools into to start the rest of the work in that room, no trips and a clean mains feed at last!

Thanks again for all your help folks.

Seri

[Martin Angove]

Bloomin' Volexes that I've been using are even more confusing. There is no numbering on the MCBs, but the (already split) neutral is numbered (IIRC) 1 to 8 (L to R) non-RCD, and 8 to 1 (L to R) on the RCD side (the live busbar is not split so that you have a (little) flexibility). The Earth, of course, is one busbar numbered 1 to 12.

So MCB 1 is non-RCD protected and the circuit connects to neutral 1 and earth 1.

The MCB furthest right is RCD protected. It should probably be numbered

12, but it connects to neutral 1 (on the RCD bar) and earth 12.

Or something like that...

Hwyl!

M.

[Christian McArdle]

I don't get these issues. RCBOs rule! Easier to wire up, too, as the entire cable goes into the top of them, without touching the neutral bus bar at all (which is not split), so no need to work out how much longer the neutral needs to be than the live and leads to neater internal wiring.

Christian.

[Martin Angove]

I'm sorry, but if it's a choice between a Screwfix populated split-load Volex (RCD and 10 MCBs) for £60, or similarly populated Wylex for £75 and £250 (yes, TWO HUNDRED AND FIFTY POUNDS) or more for half a dozen RCBOs, an unpopulated CU and a few MCBs then very few of my clients will see the logic of the latter, especially if the RCBOs are of the two-module variety and so for the same number of circuits I need to install more or bigger CUs.

Even in my own installation I've gone for a standard split-load with just one RCBO feeding a radial to the utility room / outside socket.

If money were no object then individual RCBOs make sense, if only from a discrimination point of view, but in the real world the difference between £60 and £250 is a huge percentage of the parts cost of even a complete rewire in most houses. I have recently finished a complete rewire where the parts cost was about £400 - three rings, two radials, two lights, cooker, shower, immersion, data, all new parts. They had a £60 CU, swapping that for a £250 one would have increased the parts cost by some 50%

Hwyl!

M.

[Christian McArdle]

As RCBOs cost around 40 quid, I'm interested to know why you need 6 RCBOs. I've got 3 on mine, and I'm not even using the third one yet. It is reserved for exterior electrics. The other two do ring circuits. I have 2 radial socket circuits too, for integrated appliances, but these are MCB only as the sockets are not accessible. Lighting, immersion etc. are not protected.

The first RCBO comes for free, as you would have needed an RCD anyway. Subsequent ones come for 34 quid effective, as the MCB would have cost 6. Another alternative is to split load, but use an RCBO for outside electrics, where the chances of a nuisance trip are high. So even if you protect 3 rings and the shower, you're talking about 100 quid more than a split load, like for like.

Christian.

[Andrew Gabriel]

Not from an electrical wholesaler...

[Christian McArdle]

Out of interest, where can you get them cheaper? The only sub 40 quid price I got was 30 quid from screwfix, but these were bizarrely Type C, so as useful as a chocolate teapot.

Christian.