External Garage

[heatcall]

Hi

Our external detached garage is causing the house consumer unit to trip on the protected side of the RCD. All OK when I turn off the MCB to garage. Still trips even when old garage main fuse box is off !!

Is it the 'buried' cable from house to garage??

Mike

 

[ericmark]

Give up, is it? There is only one way to answer the question, and that is test the cable.

There are two ways to fault find, one is start at one end and step by step test, the other is to have a guess at what the fault might be, and test the most likely causes first. We normally start with the latter, and if it does not work, then go to former method.

It is unlikely a wire armoured cable will degrade, so one would look at the ends first, but although it should be SWA to be buried, that is not always the case, I have seen PVC cable which was for internal use only being used outside, most PVC cables for outside are black, as black resists UV damage better.

But I would look for spiders and the like where cable terminates, and of course test, which means a meter to do testing with, think I paid around £35 for my insulation tester, which tests at 500 volt, multi meter is useless. So is it worth buying test equipment? or is it cheaper to get an electrician?

 

[AndyPRK]

have a look where the garage cable meets the house.
Is there a wet junction box ?

 

[heatcall]

Hi
The cable goes from the MCB (separate)down under floor (bungalow and not accessible)then buried for about 10m to garage, goes up the garage wall into an old fuse box. I have taken cables out of fuse box and isolated but MCB still won't set. Cable is reinforced black with the armour as earth. There are no junction boxes on the route that I can see under the floor.

mike
By the way, thanks for help.

 

[AndyPRK]

so are you stuck with part of your house off ?

is it the rcd or mcd that is tripping ?

 

[heatcall]

Hi

Just the garage, has its own MCB, if i leave that OFF then the RCB stays on.