RCD Keeps tripping during the night?

[Aquanut]

Hi All,

Got a problem with my consumer box that is starting to irritate me

The RCD has started to trip for no apparent reason to the point where it trips every night when we are in bed. I have tried to isolate the problem by switching off the fuse to the upstairs lights (still tripped) down stairs lights (still tripped) and even the sockets to no avail.

I have the garage on a seperate fuse in the consumer box and the garage also feed my shed which is only running a wireless IP camera for security reasons.

Currently if I switch the garage off the RCD does not trip so last night I disconnected the shed and left the garage on and the RCD tripped. The only thing connected in the garage is the electric door and the dryer both running from two extensions.

Any ideas on who to resolve this would be greatly appreciated.

many thanks

 

[automationman]

Good, you are going about this in a logical manner it seems. It certainly looks as though the problem is in the garage. Keep in mind that depending upon your earthing system the tripping can be caused by a Neutral-Earth short/leakage as well as a Live-Earth short/leakage. So you need to check all conductors once you zone in on the problem.
This also means that the problem could still be in the shed. You would need to completely isolate neutral and live to be sure (in fact you should disconnect the entire cable)

1) Does the trip happen at an exact time each evening? If so then do you have anything on a timer?
2) Have you unplugged the extension leads (they are a likely culprit)
3) Do you have an insulation tester? If so the isolate the garage completely (live, neutral, earth) and see if you have any leakage/shorts on live-earth, neutral-earth. Remember that a standard RCD will trip when only 30ma of leakage is present so you need to look at all details here.
4) Ultimately you may want to consider a delayed RCD at your consumer unit and a local RCD for the garage to prevent the garage from taking your house power out like this (that requires very carful planning and probably a new consumer unit in your house and garage)

5) What type of earth do you have? Do you have an earth rod or an earth provided by your electrical supply?

 

[JohnD]

outbuildings are often damp, with condensation increasing at night, this might be the cause. They also get rodents chewing cables and nesting in enclosures.

look carefully at any external lighting or switches

you have to unplug things, not just turn them off.

are you saying that the whole house and outbuildings are on a single RCD? this is not good practice for reasons you now see.

A photo of your CU, meter and service heads, and the cables around them, and the wiring to and in your outbuildings, will give us a good idea of what may be happening.

 

[Aquanut]

Hi All

Thanks for the great advice.....

The shed is solated at the moment so I can exclude that from being the cause or part of.

I intend to unplug the the dryer but leave the garage door connected or I won't be able to get in and try it again tonight.

If it still trips looks like I'll have to get a sparky in to add an additional consumer unit and put the garage and shed on to this.

Many thanks

 

[automationman]

If you are thinking of replacing the consumer unit(s) then an alternative to a delayed RCD is an RCBO (combined RCD/MCB that sits in one channel) in your case just on the garage circuit and all other circuits would be wired across dual RCDs. But you need the right consumer unit to allow for the RCBO. I think most manufacturers call them "High Integrity Consumer Units"

To do the job properly you would still need something in the garage to allow for lighting and sockets. You can get a small two way consumer unit and you would not need an RCD in it if you had the RCBO in your house consumer unit. Any fault in the garage would trip only the RCBO and not impact any of the house circuits.

As JohnD mentioned, there is a strong possibility of damp/rodents causing the current problem which you can solve quickly but long term it would be wise to consider new consumer units with good discrimination for the garage.

 

[ban-all-sheds]

I intend to unplug the the dryer but leave the garage door connected or I won't be able to get in

Unless there's an emergency and/or manual release operable from the inside that isn't very funny at all.

 

[Aquanut]

Talked to the Wife , going to move the dryer into the house for the Winter currently sourcing a 5 way CU for garage and shed

 

[ColinJacobson]

If you are thinking of replacing the consumer unit(s) then an alternative to a delayed RCD is an RCBO (combined RCD/MCB that sits in one channel) in your case just on the garage circuit

This sounds OK. One RCBO in the CU (not off an RCD) and a small CU in the garage doing the garage and shed.

 

[ban-all-sheds]

Or just an MCB or split tails & switchfuse at the house if there's no requirement to RCD protect the cable to the garage....