blowing trip

[timber41]

I am trying to get power to outbuilding, but am having trip trouble with the extension wire, but not consistently. If i put an extension cable in, and run a welder or other power hungry device, things can be fine. If i plug in another extension but dont even have anything plugged into it, it will blow trip, whereas if i plug this extension straight into house its ok. Is it something to do with leakage...it blows main trip only (the main box doesnt have a split box or whatever its called). Can main trip be too sensitive?

 

[industryspark]

If you need power into your outbuilding it would probably be better to have an electrician hard wire a circuit to your outbuilding and then have some sockets/lights in there to meet your needs.

Running extensions is less reliable and more dangerous and is ok for temporary stuff but if your wanting power long term i would recommend something hard wired.

When you say 'trip', do you mean the rcd is blowing in the Consumer unit? Are you plugging the extensions into the same socket to try them. You may have a faulty extension, maybe get them checked out? Your descriptions are slightly vague so hard to say what the problem may be. No offence intended.

Regards

 

[ccam108]

Check all plug tops for an earth cable being nicked by the neutral pin. This will blow an RCD.

We had one in the church - was probably like that for years. We only noticed a while ago when a visiting band set up their own PA for a gig and got the most horrendous 50Hz buzz from their kit. Was a bit of a head-scratcher working out why a reel with nothing in it would do that.

This was a while ago before we got RCDs put in though. Now it would just trip instantly and confuse us even more!!

Colin C

 

[timber41]

Thanks for the replies...I know they are a bit vague but the problem is very inconsistent - things can be fine for a day or two, so its hard to pinpoint the problem. Yes, the main rcd blows, but not the specific trip (does that mean anything specific - why not trip the allocated trip?) Hard-wiring would be sensible, but needs to be dug under concrete etc. The outbuildings were done by electrician, and the connection worked fine for a while. Can it be due to too many piddling little earth or neg leaks?

 

[ccam108]

Thanks for the replies...I know they are a bit vague but the problem is very inconsistent - things can be fine for a day or two, so its hard to pinpoint the problem. Yes, the main rcd blows, but not the specific trip (does that mean anything specific - why not trip the allocated trip?) Hard-wiring would be sensible, but needs to be dug under concrete etc. The outbuildings were done by electrician, and the connection worked fine for a while. Can it be due to too many piddling little earth or neg leaks?

Does each circuit have an RCBO? (Are there little test buttons on each trip?) If not, that is why the main switch is tripping, as it is the only RCD protecting the whole house. This is not a problem, just more of a nuisance. It is not generally allowed in new installations though.

Inconsistent tripping could be due to a lot of individual appliances adding up to nearly 30mA of leakage. Something new must be pushing it over the edge.

We have this problem in our house with too many computers, occasionally it will trip for no apparent reason.

To the experts: Would the capacitive coupling between cores in a long extension lead cause any earth leakage at all?

Ah and also, I meant "This will trip an RCD", not "This will blow an RCD" earlier sorry.

Colin C

 

[timber41]

Thanks, i think the sum of lots of little leaks sounds plausible...is 30mA the max allowable, or can I up this at my own discretion - if so are there underlying problems that will kill someone oneday!!!

 

[PrenticeBoyofDerry]

30ma is the requirement, higher could be dangerous.
Does extension lead have an RCD on it too?
When the extension lead trips in the out building is it plugged in to the same socket-outlet as when it trips inside the house?
Are all your circuits covered by the same RCD?