John wrote:
I have a separate garage that has power supplied from my house RCD equipped
CU. In the garage there is a separate two way CU (lights and sockets). The
sockets in the garage are all twin plastic apart from one twin metalclad, a
total of 4 twins outlets. They are all daisychained off the previous one
i.e. ----Feed from
house----[CU]-----[Skt]--------[Skt]-------[Skt]-----[Skt]. These were all
in when we moved in.

I have lived here for 12 years and over the last couple of months the garage
MCB in the house has tripped intermittently.

You mean the RCD is not tripping? so its current overload and not earth
leakage that is happening?


The only thing in the garage
that is permanently plugged in is a freezer (and it has been for 9+ years).
I tried plugging the freezer into different sockets to try to eliminate it's
'normal' socket but it still kept tripping. Today I plugged in my socket
tester and found one socket didn't have an earth, this socket isn't the
freezer's normal socket. I traced this back to the previous socket and
reattached the earth wire. I then looked inside the freezer's plug top and
found the live conductor was loose. The copper strands were still inside
the hole but the screw wasn't tight. The plug top has never been apart
before so either it was supplied like this from new or it has worked loose.
I have now tightened this up. Neither of the loose wires were able to touch
any other conductors.

My question is am I likely to have found the problem?

Probably not.

It is JUST possible that a continuous high current arc was overloading
the MCB, but you would have found evidence of extreme arcing and burning
in the plug.

I can keep checking
but this means me having to stick my head in a cupboard and cricking my
neck. I will check periodically but have I sorted it? I can also check on
most days when I go in the garage and switch the lights on.


Frankly if you are overcurrenting the thing, you have a wiring short or
a faulty freezer, and its likely to go bang sooner or later and take out
the wiring.

Happened to me when I painted a kitchen in a rented house. the paint got
into a hole with a rawlplug in left over from some previous shelf, and
as it happened, the thing had been neatly drilled through a ring main.

The landlord blamed me and refused to give my deposit back when I left.

I got the last laugh though, because my deposit was three months rent in
advance, and then I paid monthly in advance after that. There was no
deposit to give back ;-)