RCD tripping

[daveplum]

I've a new split consumer unit; 1 ring and lights not protected, 2 rings and cooker protected by RCD.
All ok, until I power on a computer on a RCD protected ring, then it trips. I can then reset, and all ok (so I assume nothing's actually faulty), and I can continue to power up the computer. It seems to be the actual act of switching it on initially.
Any ideas why this should be the case?

 

[breezer]

it sounds like there is a problem with the power supply for your p.c. but it could be the socket or connecting cable earth

what happens if you plug in your pc else where? and what happens if you change the lead to the pc (borrow the one from the kettle)

 

[masona]

what happens if you change the lead to the pc (borrow the one from the kettle)

The problem I can see,you might get steam's coming out of the pc

 

[spark]

I think masona's been at the laughing beans again, he's been on top form over the past few days...

I'm in agreement with breezer, does sound like the pc power supply is chucking just that bit too much leakage current down the earth. It may not actually be that much but just enough to tip it over on start up. It could be that the accumulative leakage current is above average on all the circuits combined and the pc starting is just enough to pop the RCD.

You may have an over sensitive RCD, in which case changing it may cure it, if not then it might be worth changing the PC power supply. Do the checks breezer suggested foirst though, it could save a lot of hassell.

 

[ban-all-sheds]

Computers often generate earth leakage current, and on startup the surge can be relatively high. I'm surprised it's so high that it trips an RCD. Do you plug straight into a socket, or have you got one of those surge protection strips? If so, have you got other things plugged into it which may be generating earth leakage current via the protective circuitry in the strip, even though they don't do so directly?

But I agree with the above - get it checked out. Any device that generates more than 3.5mA should have a warning sticker, and I've never seen one on a PC, so there may be something wrong.

(It is a PC, isn't it? Not one of these?:

)



If you're interested, here's the why: http://www.tlc-direct.co.uk/Book/7.8.1.htm

and here's how your installation should be wired: http://www.tlc-direct.co.uk/Book/7.8.2.htm

 

[daveplum]

Thanks for all the suggestions; will check them out.
One or two further details prompted by the very informative feedback, and from further investigations:
1. It is plugged in to a surge protector strip, along with other items. If I disconnect all items, switch on at wall, then plug in the computer to the sps it trips
2. I think the socket the sps is plugged in to is a spur (direct from the consumer unit (I didn't do it, honest, I've only just moved in))
3. Oddly, it's tripping just when power is switched on at the socket/sps ie before I press the power switch on the computer's front casing.
4. And it's more towards the size of the kettle than those in the photo from ban-all-sheds (ps thanks for the v interesting links).

 

[Dave12345]

Thanks for all the suggestions; will check them out.
One or two further details prompted by the very informative feedback, and from further investigations:
1. It is plugged in to a surge protector strip, along with other items. If I disconnect all items, switch on at wall, then plug in the computer to the sps it trips
2. I think the socket the sps is plugged in to is a spur (direct from the consumer unit (I didn't do it, honest, I've only just moved in))
3. Oddly, it's tripping just when power is switched on at the socket/sps ie before I press the power switch on the computer's front casing.
4. And it's more towards the size of the kettle than those in the photo from ban-all-sheds (ps thanks for the v interesting links).

There will be a switch on the back of the PC near where the power lead goes in. This is what switches it on and off. The switch on the front is a bit like taking the power supply out of a stand by mode. (Unless the PC is more that about 5-6 years old then the switch on the front will be switching mains voltage).
PC do drop a certain amout of current to earth though the case. (On the old ones there use to be a 12V ac potential to earth when the earth was disconected not shoure what it is on the ATX types never tested it). They do this because it creates a certan amouth of EM shilding for the components in side. As the processor is very seseptible to induced curent.

I have never known wone to though a RCD though. How ever I have seen some very strange behavure with the power leads them selves. We have some monitors hear that if the main RCD in the building as triped. you have to unplug the leads from the flore and the back of the monitor then plug them in again befor they will come back on. Just unpluging one end will not do any good.
(I would love an explanation for this one we cant find any reason for it).

So I would sugest unpuging the hole computor reseting the RCD and then pluging things back in making shoure the mains switches on them are off.
and try to isolate exactly what is trigering the problem.