Fred wrote:
On Mon, 07 Apr 2008 13:24:12 GMT, Fred
wrote:

In the future I would like to add a motorised door to the garage.
There is no other door into the garage so if the RCD trips I will have
to wind the door by hand! Would it be better to put the RCD outside
the garage, i.e. under the stairs? Notwithstanding the freezer
problem, why can't I have the RCD inside the house, rather than inside
the garage? The advantage of that would be that the whole 6mm^2 (or
10mm^2) cable run would be protected from house to garage.

To try and answer my own question: is the downside to locating the RCD
in the house that in the event of a trip you will have to check two
separate CUs: one in the house and one in the garage? OTOH if I went
with plan A and just had a fuse in the house, I suppose I would have
to still visit both boxes to see whether the fuse had blown or an MCB
tripped.

With the RCD in the house, you make it difficult to avoid having the
feed to the freezer sharing a RCD with other devices, hence the
implications of a trip are worse.

The fuse in the house is also highly unlikely to trip if sized
appropriately for the submain.

I suppose that I also need to measure the length of the cabel run to
make sure that if the RCD is in the house, all the disconnect times
are still within limits?

The only time is it likely to be a factor is if your earth loop
impedance is marginal in the garage. In which case you would be better
off making the garage a TT install in its own right.

Can't remember if you have posted the type of earthing in your house, or
the length of the run to the garage. If you let us know those it should
be easy enough to give a worst case estimate.


--
Cheers,

John.

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