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Hi all
I need abit of advice I work mainley in refrigeration and my next job is installing a cold room nothing unusual apart from the unit is 50 metres from a power supply which is brought in via an overhead supply so Iam thinking TT I intend using 2.5 SWA buried, load is 7.5 max running amps with a locked rotor amperage of 37 amps my question is twofold volts drop and earthing shound I incorporate an earth rod near to the installation and will going up to 4.0mm SWA take care of volts drop and will a 16 amp mcb handle the demand and afford adequate protection
devlin

You need to know if it really is a TT supply or maybe it has been PME'D as a lot of overhead supplies have been altered like this. If i was you I would run the supply to the freezer in 6mm armoured , and protect it with a c16 Breaker in the distribution board. How is the cable terminated at the freezer? has it got its own distribution board ? I wouldnt bother with an earth rod, just wire the feed in 3 core SWA .

Nick

Hi
Thanks for the reply this is a new supply to an organic produce farm so I would think then its PME But can I check that with the supply company
The cold room is housed in its own timber building and I will be installing a ring circuit and a couple of flu lamps So I think your idea of its own consumer unit would be good
As to earthing should I use the armour or is it best to use yellow as earth properly marked of course
Thanks again if you have any further thoughts I would wecome them
devlin

If your planning on using the store for more than just a coldroom then you will definiteley need a distribution board to split up the lighting, and the ring main which will have to have rcd protection as it could be used to supply equipment outdoors. You will probably have to install a split load distribution board with the freezer and lighting on the Non RCD side and the sockets on the RCD side, or just use RCD sockets . How many sockets are you looking at installing and lighting? You need to work out the maximum demand you will be using there, and then the cable can be sized accordingly. the earth will have to be a core of the SWA , but not yellow as the colours have changed, in a 3core SWA the colours are brown black and grey, brown will be live, black , sleeved/taped as earth and grey sleeved or taped blue as neutral.


Nick