Fuse Box Keeps Tripping . . . is it my PC set up?

TheSalad · 2 Apr 2010

Hi All - our fuse box keeps tripping when we unplug the PC at night. The fuse that trips is the big one in the centre of the picture below, sixth in from the left.
View media item 21180I have no clue on electrics but I think it may be to do with the load we have. A double socket on the wall, both feeding an extension lead with four additional sockets on each, so eight appliances being fed in total (PC, printer, monitor, speakers, BT homehub etc etc . . . .). Did I explain it OK?

Is there a recommended set up for all the appliances connected to a PC, so that they can all be safely turned off at night.

Hope you can help.

bongos · 2 Apr 2010

It is your RCD that keeps tripping. It is protecting all the socket circuits in your house against earth leakage.

If you have alot of appliances pluged in then it is possible that the accumulated earth leakage is enough to cause the RCD to trip. IT equipment does cause earth leakage and while you wouldn't expect too much in your installation it is possibly enough to tip the RCD over the tripping threshold.

Although it is rated at 30mA, the regulations say it must trip anywhere between 16 - 30mA. If it is on the sensitive side of the scale then this could be causing you the nuisance tripping.

An option is to move one of the socket circuits to the non RCD protected side of the CU and replace with an RCBO. This combines overcurrent and fault protection in one (an RCD and MCB in one module). I'd be inclined to move the one with the computer equipment on it.

TheSalad · 2 Apr 2010

Thanks v much. Is that something I could do myself or would I need to get in an electrician?

Steve · 2 Apr 2010

TheSalad said:
Thanks v much. Is that something I could do myself or would I need to get in an electrician?

You'd need an electrician.

The major problem with bongos' plan is that the circuit may still need RCD protection. I'm a little shaky on the 17th regs but I thought all sockets require RCD protection now. Certainly concealed unprotected cables require it, so this new circuit would have to be run on the surface perhaps in trunking, or in armoured cable.

Perhaps putting this circuit on an RCBO would be a more convenient solution, so that when it trips you only loose this circuit, as opposed to all 3 on the RCD. Another problem is there are no spare ways on the non-RCD side of your consumer unit. It would need reconfiguring, by which time you might as well have it 17th editioned (all circuits RCD'd)

An electrician will be able to tell you whether the RCD is over sensitive. Certainly your setup is nothing unusual, and shouldnt be loosing 30mA to earth.

ColJack · 2 Apr 2010

read it again steve, he does say to move it to the non rcd side and put it on an rcbo..

why do you unplug it at night? if it's that which is causing the tripping, leave it plugged in....

Steve · 2 Apr 2010

oops

ColJack · 2 Apr 2010

is it just my eyes or do you have a bell on a 16A breaker?

Steve · 2 Apr 2010

ColJack said:
is it just my eyes or do you have a bell on a 16A breaker?

He also has two MCBs which appear to do nothing. Perhpas it was a wholesalers special, prefilled board for £60. Though wouldnt think they'd do it with quality SquareD stuff. More a Hager/Wylex/Contactum technique

plugwash · 2 Apr 2010

What exactly are you unplugging when the trip happens? extention sockets from the wall? computer from extention socket? IEC lead from computer?

How old is the computer?
What brand is the computer? (in particular is it a cheap no-name machine)

If you can get access to a PAT tester I would suggest leakage testing the equipment both normally AND with live and neutral reversed (you will probablly need to make a special IEC lead with live and neutral reveresed to do this).

Monkeh · 2 Apr 2010

Also a good question: Why are you unplugging your PC?

TheSalad · 6 Apr 2010

There are so many appliances being fed from one socket it seems the safest thing to do. Am I being over cautious ?

Monkeh · 6 Apr 2010

TheSalad said:
There are so many appliances being fed from one socket it seems the safest thing to do. Am I being over cautious ?

Yes? It's protected by no more than a 13A fuse..

ericmark · 6 Apr 2010

A UPS may cure the problem.
UPS = Uninterruptable Power Supply

Depends on type but some convert the mains power to DC which charges a small battery and then this power is turned back to AC to feed computer and in so doing isolates the live supply from PC and so stops it tripping the RCD.

It is all down to the filters in power supply in PC and changing PC power supply could also stop the problem.

It could even be because you are using filtered sockets.

Note:- Live means Line and Neutral

I had same problem here with 4 desk tops but once my daughter left and down to two desk tops it is no longer a problem.

For some reason the switch mode power supplies used with Laptops don't seem to cause a problem and at college we work in a room with 20 MAC Computers and they never trip out. So although it is made worse the more PC's are being used it really is all down to PC power supply manufacture and even the DELL PC's at college don't seem to have a problem but in University they did in the PLC lab so since in PLC lab we used all the old PC's I would assume it is something which has been redressed with latter models.

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Fuse Box Keeps Tripping . . . is it my PC set up?

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