RCD Trips when Computer unplugged

[richardr1981]

My Mum's house, which has a whole-house 63 amp (30mA) RCD protecting the whole house (as you can tell it's a small house) occasionally trips after the home PC (plugged into a surge protection adaptor, along with the Modem) is shut down and then unplugged.

I have read thge debates about computers, surge protectors and Earth-Leakage, but this happens after the computer is turned off, not while it is running. And, as I have said, it only happens occasionally.

Other things (including High Risk stuff like the kettle, outdoor lights, and whirlpool bath) work fine.

Any thoughts as to what this might be? Faulty socket perhaps (it is Earthed Decarative Bass sort). Any advice/experience gratefully received. Thanks

 

[PrenticeBoyofDerry]

Does this happen at the time the PC is unplugged or is there some delay,
Just to confirm it is the RCD that trips, not the MCB?

 

[richardr1981]

Does this happen at the time the PC is unplugged or is there some delay,
Just to confirm it is the RCD that trips, not the MCB?

I understand pretty much at the time it is unplugged. Definately the RCD not an MCB that trips. Oh and it can be reseet straightaway. Thanks

 

[JohnW2]

My Mum's house, which has a whole-house 63 amp (30mA) RCD protecting the whole house (as you can tell it's a small house) occasionally trips after the home PC (plugged into a surge protection adaptor, along with the Modem) is shut down and then unplugged.

I suspect it's ironically a 'surge' to earth (possibly a discharging capacitor)being created by the 'surge protector' when it's taken completely off load, so I imagine that it would not happen if you did away with the surge protector. Don't forget that, even when 'shut down' the PC is still partially on (like a TV on 'standby'), and therefore presenting some load to the surge protector.

Kind Regards, John.

 

[richardr1981]

My Mum's house, which has a whole-house 63 amp (30mA) RCD protecting the whole house (as you can tell it's a small house) occasionally trips after the home PC (plugged into a surge protection adaptor, along with the Modem) is shut down and then unplugged.

I suspect it's ironically a 'surge' to earth (possibly a discharging capacitor)being created by the 'surge protector' when it's taken completely off load, so I imagine that it would not happen if you did away with the surge protector. Don't forget that, even when 'shut down' the PC is still partially on (like a TV on 'standby'), and therefore presenting some load to the surge protector.

Kind Regards, John.

Thanks. That is sort of my view too. I even changed the last surge protector (thinking the last one may have been faulty), but no change. I will happily do away with altogether, but aren't surge protectors needed to protect PC equipment from voltage spikes (or are they just one huge con??)

 

[JohnW2]

Thanks. That is sort of my view too. I even changed the last surge protector (thinking the last one may have been faulty), but no change. I will happily do away with altogether, but aren't surge protectors needed to protect PC equipment from voltage spikes (or are they just one huge con??)

Well, for what it's worth, my humble opinion is that your last few words there are the case! Have you tried it without the surge protector?

Kind Regards, John.

 

[westom]

That is sort of my view too. I even changed the last surge protector (thinking the last one may have been faulty), but no change.

Surge protector is irrelevant. Also does not work as he has posted.

RCD essentially counts the number of electrons going out on a hot wire and coming back on the neutral. If a miscount is too large, an RCD trips. So, why would current be going into the computer but not back via the neutral wire? Your solution is found only in the answer to that question.

Numerous reasons can explain it. For example, a line filter inside a computer’s supply can be defective. But since neutral and safety ground are at nearly same voltage, then not enough electrons go in the wrong direction.

When you unplug, safety ground remains connected. If a neutral prong disconnects before hot prong (on the AC plug), then a defective filter is now conducting too many electrons into safety ground.

Protectors do nothing. Remain inert until AC mains voltages well exceeds 500 volts. Can only trip an RCD when it has failed and a thermal fuse also failed to trip (to protect human life). Both failures must exist. Only then the RCD would trip. But would trip without disconnecting a plug. In short, the protector would obviously be irrelevant.

You have current flowing from hot wire into a safety ground when its plug disconnects. A defective line filter in the computer's PSU is one reason why an RCD would trip. An experiment could prove it.

 

[ebee]

try changing the plug and socket or use a switched socket.
Do you need to unplug it?

I found a similar problem with an immersion heater a few years back.
20A DP switch - switch off and RCD tripped. Changed switch - no problem.
N switching off before L ?

 

[bernardgreen]

N switching off before L ?

Or the switch in the neutral !

With the neutral removed then all the mains wiring, both live and neutral, in the appliances is at 230 volt ( via the appliances ). Now all the capacitors to earth ( CPC ) in filters and surge supressors are beween either true live or the 230 volt neutral so the earth leakage current ( from the capacitors ) is double that when the neutral is connected.

 

[ericmark]

A lighting storm can cause the RCD to trip. Clearly nothing to do with a fault on equipment and just caused by a spike. Modern RCD's are designed not to trip with spikes but older types did have this problem. Can't find write up at moment but there is one with a warning lamp so show when near limit.

Normally a house would have at least two 30ma RCD's and to use just one is asking for problems. With 100ma used for TT supplies using one with a delay is OK but not with 30ma.

There are some very expensive types like this

Untitled

• ericmark
• 6 Dec 2008
• 34

designed to auto reset and between these and the much cheaper standard type there are different qualities and one has to decide what it is worth.

Using a UPS may help I have used these in the past and they did help where an office had 20 computers. They were bought to stop losing info when RCD tripped but after installing found RCD no longer tripped.