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Surge protected extension lead tripping rcd?


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14 replies to this topic

#1 Mr Sworld

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Posted 03 January 2009 - 10:06 AM

Hi guys.

I've had a problem with an rcd for a while. It randomly trips out every now and again and the fault is intermittent. X(

It did it this morning and I mangaged to track the fault down to the downstairs radial. After turning off equipment I think the fault is from a surge protected 4-way extension lead with two items of class II equipment plugged into it. At least when I unplugged it the fault disappeared but when I turned it on again the rcd stayed on!

Anyone heard of these items causing rcd trips?

#2 Apache

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Posted 03 January 2009 - 11:05 AM

Hi guys.

I've had a problem with an rcd for a while. It randomly trips out every now and again and the fault is intermittent. X(

It did it this morning and I mangaged to track the fault down to the downstairs radial. After turning off equipment I think the fault is from a surge protected 4-way extension lead with two items of class II equipment plugged into it. At least when I unplugged it the fault disappeared but when I turned it on again the rcd stayed on!

Anyone heard of these items causing rcd trips?


No I havn't but I have had a few cheap and nasty ones over the years - 1 had a neon light that flickered if you plugged anything in.

Cheapest and easyest to chuck it away and get a new one - or the 'better' approach and fit another DSO or two?

#3 Andy™

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Posted 03 January 2009 - 11:14 AM

if you have ever meggered one, youll probably find its around 1meg or less to earth

#4 Badger

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Posted 03 January 2009 - 12:36 PM

i dont like plugging long extension leads in for pcs tvs dvd players, etc, would much rather have a socket for each item :)
we have six surge protected sockets behind the computer desk and all the cctv monitors ;) dvr, joystick for domes ;) and pc and pc monitors, router,. printer etc
all have their own surge socket which is own a standard socket type with green switches

#5 batty

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Posted 03 January 2009 - 03:49 PM

Mr S
We have about four or five in our house going through one RCD with no problems. I would think either it is faulty or you have another problem on circuits.
Batty

#6 Mr Sworld

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Posted 03 January 2009 - 03:56 PM

Cheers guys.

It's a right pain in the proverbial as the fault is:

a) Intermittent; and

B) It clears itself without any real explanation as to why!

I might drag the extension to work and PAT test it to check it over.

#7 davetheglitz

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Posted 04 January 2009 - 01:09 PM

Just a thought. These things are voltage dependant. When you do an insulation test - with one of these in circuit it will be around 3M at 500v but around 0.3M at 500v.

Assuming a voltage spike occurs for some reason due to switching/lightening strike - whatever - it's feasible that the resistance to earth will drop down below 8k (240v at 30mA) and cause the RCD to trip. This would explain the random nature of the trip.

I would suspect that the trip occurs when there is virtually nothing else on in the house, as I reckon a substantial load like a cooker or heater would prevent the voltage spike building up.

Of course it could just be knackered!

#8 septiclecky

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Posted 04 January 2009 - 01:39 PM

Just a thought. These things are voltage dependant. When you do an insulation test - with one of these in circuit it will be around 3M at 500v but around 0.3M at 500v.

Assuming a voltage spike occurs for some reason due to switching/lightening strike - whatever - it's feasible that the resistance to earth will drop down below 8k (240v at 30mA) and cause the RCD to trip. This would explain the random nature of the trip.

I would suspect that the trip occurs when there is virtually nothing else on in the house, as I reckon a substantial load like a cooker or heater would prevent the voltage spike building up.

Of course it could just be knackered!


We had apiece of equipment in a gym where I worked when they PAT tested it it failed on the insulation test, found that it was fitted with a surge protector which caused it to fail on 500v setting but OK when tested on 250v setting.


Problem could be that components in surge unit are breaking down intermittantly thus causing RCD to trip now and again.

#9 Mr Sworld

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Posted 04 January 2009 - 09:23 PM

We had apiece of equipment in a gym where I worked when they PAT tested it it failed on the insulation test, found that it was fitted with a surge protector which caused it to fail on 500v setting but OK when tested on 250v setting.


Problem could be that components in surge unit are breaking down intermittantly thus causing RCD to trip now and again.


This is what I suspected. I think there is some components in them that link the earth to the live and neutral. Which, if they are breaking down, would cause a earth leakage to occur.

It's a Belkin though. Supposed to be the top brand! :(

#10 septiclecky

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Posted 05 January 2009 - 12:59 PM

This is what I suspected. I think there is some components in them that link the earth to the live and neutral. Which, if they are breaking down, would cause a earth leakage to occur.

It's a Belkin though. Supposed to be the top brand! :(


Just because it is a top brand, parts still do fail with time.:o

#11 Mr Sworld

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Posted 23 January 2009 - 04:22 PM

It tripped out again today! X( However this time the fault lasted long enough to figure out what the problem was!

It wasn't the lead after all, it was the CH/HW system! So after opening up the wiring centre (which resembled a dogs dinner, why can't plumbers follow the wiring diagram?) I unwired each bit.

Not the pump!

Not the room Stat. Or the tank Stat either!

Not the controller.

Which left the 3-way valve. So unhooked that and the rcd stayed on! Success! :D

Opened up the top and found a small amount of water leaking from the valve and just touching the pcb board! Dried it up and reconnected the valve wiring and all stays on!

Now how the hell you would of had a chance of diagnoising that if you were called out for it I would have no idea! A random rcd event that would clear as soon as you reset the trip sometimes.....

#12 Andy™

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Posted 23 January 2009 - 04:24 PM

Now how the hell you would of had a chance of diagnoising that if you were called out for it I would have no idea! A random rcd event that would clear as soon as you reset the trip sometimes.....


unless the fault is still there when you arrive... you have very little chance of finding anything so retrn visits probably needed... and hope that it stays faulty long enough to find

#13 batty

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Posted 23 January 2009 - 06:47 PM

Mr S. they certainly are not easy to find on heating systems. I got called out to one a few weeks back. It was blowing the 5 amp fuse (oil boiler) as soon as you turned spur on. Insulation resistance was about 20meg. Boiler man was there but I could not figure it out as 20meg was not enough to blow fuse I thought any way he changed a part on boiler and this seemed to cure it but what I could not understand was why fuse went before boiler fired anyway have not been called back so assume this was what problem was.
Batty

#14 davetheglitz

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Posted 23 January 2009 - 08:29 PM

Opened up the top and found a small amount of water leaking from the valve and just touching the pcb board! Dried it up and reconnected the valve wiring and all stays on!


Nice one! I had a similar fault once with a Worcester boiler with a drip onto the PCB. Would trip the RCD in the middle of the night but would evaporate by morning so the RCD could be reset. I managed to trace the fault to the boiler - but the boiler engineer was lucky and actually saw it happen (so I was told).

#15 kme

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Posted 27 January 2009 - 12:17 AM

The latest one - customer had 30mA RCD fitted in place of the front-end 100mA - intermittent tripping. 3 time in a day, then stayed on for a week. Everything unplugged / everything running. Didn`t matter.

Finally - the exciter in the room stat, which had been there for many a year, working away happily, was connected to 1 of the cores in a T+E.....Guess which one????

Grrrrrrrrr. I abhor plumbers. They make my life so much harder than it ought to be!!!




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