Consumer Unit and External Trip

lloyda · 28 Jan 2010

I had a new CU installed when I had my kitchen replaced recently, as the old one was of the rewirable variety. I never saw the guy who did it, but I do have the Part P paperwork.

Last night the wife turned the steamer on to cook the veg for dinner, and the whole house was plunged into darkness. Nothing had tripped in the CU, but a 30mA trip which had been left between the meter and CU had tripped. (I describe it as a trip because I'm not sure what it is.)

No realising the issue was the steamer, we plugged it in again. This time both the external trip, and half the CU tripped.

My question is should the extra trip have been removed? I can see the attraction of it being there for the guy working on the CU change, but should it have been taken out?

(The steamer is now in the bin. 13 months old. Fantastic design!)

Thanks

mfarrow · 28 Jan 2010

Do you have a TT supply or a TN-C-S/TN-S supply?

- TT = main earth bond through a hole to a stake outside
- TN-C-S/TN-S = main earth connection from the CU to the incoming supply cut-out (the suppier's main fuse before the meter).

If you have the former then you will need to retain some sort of RCD protection. on the entire installation.

You say half the board tripped (presumably the breaker has a test button on it). Is the other half of the board also protected by an RCD.

timtheenchanter · 28 Jan 2010

could have been left in as a convenient isolator, so he did not have to arrange for the main fuse to be pulled.

without knowing more about the install (ie is there an RD in the C/U) what was agreed for the replacement CU its hard to say if it should have been left or not.

rebuke · 28 Jan 2010

If you can upload a picture of your CU, and this extra 'trip', and also any pictures of the service head (the bit that sits on top of the cable coming in from outside that then goes to the meter etc), we can probably tell you if it's required or not...

lloyda · 1 Feb 2010

Thanks for your replies. Have taken some pictures as suggested. I think they are self explained. In case anyone is wondering, the earth cable which goes through the cutout with the incoming feed is to earth the gas supply.

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electronicsuk · 1 Feb 2010

No, that trip should not be there and should have been removed. Even if you were on a TT supply, the fact that all your outgoing ways in the CU appear to be protected by a pair of 30mA RCDs negates the need for another device upstream.

Hope he didn't charge you too much for parts - that consumer unit looks pretty cheap.

Steve · 1 Feb 2010

top quality CU that.

robbie77 · 1 Feb 2010

What's wrong with it?
It looks like a CHINT one like mine

Apparently they are chinese but good quality if the two can be said in the same breath.

Have you heard bad things?

Steve · 1 Feb 2010

Wouldnt you rather use something made in Europe and used and tested widely throughout Europe in your home? Hager, MK, Siemens.

Chint, MCG, C-PAK, all cheap rubbish fitted by electricians who should know better.

robbie77 · 1 Feb 2010

Steve said:
Wouldnt you rather use something made in Europe and used and tested widely throughout Europe in your home? Hager, MK, Siemens.

Chint, MCG, C-PAK, all cheap rubbish fitted by electricians who should know better.

Had i known better when i bought it then maybe but I haven't heard anything particularly good or bad about them.

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Consumer Unit and External Trip

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