On 10/09/2017 15:47, wrote:
Hi all

I have had another look at the setup based on my new knowledge. There
are 2 motors connected into a waterproof junction box. Looking at the
junction box the incoming earth is connected to the earth going to
both motors. There is then an earth wire going from the base of one
to the metal framing which the legs are attached to. The motors have
screws coming out of the bottom with thick rubber washers on. These
screws then fed through a metal board where they are bolted in place.
This board is attached to the metal framing.

The motors have a label on them but no mention of class 1 or 2.

If the motors have an earth connection in their flex, then they are
class I. (generally if its metal cased and not marked as class II then
its best to assume class I)

So... Judging from the about it sounds like I should be fine with
wiring the mains into the junction box as normal. With the frame
bonded to one motor and it in turn seems to be connected to the
incoming earth.

So long as the earth of the circuit feeding the motors is included in
the rooms EQ bonding, then you don't need anything else. The protective
conductor feeding the motor itself will serve dual purpose as both earth
and bonding connection.

On the junction box it has a label from manufacturers saying it is
2.1kW and needs a 16a fuse. Is this ok to be on the ring main I plan
to extend and located as a switched fused inside the cupboard.

Its likely its an induction motor, and will have a high inrush current.
Hence the need for a higher rating of fuse than nominal[1] 10A that the
2.1kW rating would suggest.

It might be worth tracking down the manual for the motor if you can to
see if it actually specifies that the motor *must* have additional
protection from a 16A device, or whether it is just highlighting that
protection with a 13A fuse in a SFCU etc unlikely to hack it due to the
high inrush.

If it specifies that it must be protected at 16A device, then it will
make your task a little more interesting if you want to feed it from a
spur on a 32A ring circuit. You would then probably have to use a MCB,
or a HRC cartridge fuse in a suitable enclosure instead.


[1] Induction motors also tend to have non unity power factors, which
can increase the actual maximum current drawn.



--
Cheers,

John.

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