Mike G wrote:There is a three phase supply on a pole about 8 or 10 metres from my workshop, on my neighbour's farmland. What is involved with bringing 3 phase into the workshop? Is it just a single armoured cable and some sort of consumer unit, or is there more to it than that? What happens to the lights and sockets that I want to be single phase? I'm told that the overhead cabling is 415 volts. Does that mean I need a transformer?
You first port of call will be to call POWERGRID or whoever owns the supply line. I filled in a request via Northern Powergrid's website, it was quite easy.
They'll contact you with an estimate, (usually quite under!) then provide a final quote to book in.
They'll come out and connect a supply cable and install a 3 phase cutout (the bulky fuses 80-100A) to the closest point/ meter cabinet on your property (they choose location, usually) You then contact an energy supplier (Sainsbury's, British Gas, etc, etc) to install a meter (FOC) so you can be billed and have something to connect to.
Now you and your sparky are ready to connect a consumer unit/ distribution panel to the meter.
If the meter is away from the workshop (e.g. lets say a box on the boundary of your property) then your sparky would install a fused switch (box with an isolation kill lever/switch) here and you would run some 4 core SWA with an separate EARTH to the workshop and distribution panel. With the diameter of the cable being based on distance run. Mine is 25mm as it's running 50meters (voltage drop). I'm not sure if the fused switch is mandatory, your sparky would know, It does protect the 3 cut out fuses.
In your workshop distribution box you'll have 3 phases L1, L2, L3. All your single phase domestic style supplies (lights, ring, heaters,) will tap into any ONE of these. Your 3 phase machines will use all three.
In my case my 3 phase 'cut-out' also supplies the house ....my house connects to L1....my workshop lights and ring are on, L2 & L3, and my workshop machines are on all three L1,L2 & L3. This is so the supply is balanced. A good sparky should ask about all the things you are planning on running and calculate this for you.
It cost me £3000 to have 3 phase run 7m across the road and a cut out installed on my property (which is right next to the pavement). Any works on your property have to be prepared by yourself before. The requirements are usually explained before hand.
HTH....Maybe too much detail
Jim