wiring 110v sockets

davelerave

I'm looking for advice on wiring 110volt 16A workshop sockets(about 10,light use).
I guess i'll need something about 5kva, C.T.E. secondary with maybe 2-phase(380v) input.
Also i assume i'll need 2-pole short-circuit/overload protection on the secondary 16a circuits .Any advice appreciated thanks

2011

davelerave wrote: »

I'm looking for advice on wiring 110volt 16A workshop sockets(about 10,light use).
I guess i'll need something about 5kva, C.T.E. secondary with maybe 2-phase(380v) input.

I would have thought that a 3 phase supply would be more normal. It would be better balanced. I have not seen 2 phase transformers for 110 volt appliances, but perhaps there are some.

I guess you mean center tapped earth by C.T.E. ??

Also 5KVA sounds a bit small to me even for light use. Too large a transformer will not cause any problems, too smal will!! What you have to watch for is that some transformers are not designed to be switched on all of the time. I sounds like your installation is a permanent one rather than a temporary type set up for site works so I would select the transformer accordingly.

Also i assume i'll need 2-pole short-circuit/overload protection on the secondary 16a circuits

It is possible to buy 2 pole RCBOs for 110 volts, that would be the best way to go IMHO. If you are using 16A sockets it would be best to use 16A RCBOs. Some people may feel that this is over the top, but workshops are dangerous places.

Good luck with it.

davelerave

i don't have any supplier yet for trafo.i did a google and they seemed to be 230v or 380v(2 phase) input . i guess 3-phase would be more suitable as i may need about 8kva.it'll be wall-mounted suitable for 'continuous duty'.
i'm assuming just a c-type mcb and isolator for input.Is earth-fault protection required on 110v? .It would ensure 'automatic disconnection' anyhow with a 55v fault

2011

i don't have any supplier yet for trafo.i did a google and they seemed to be 230v or 380v(2 phase) input

Talk to your wholesaler. My guess is that he will suggest a 3 phase traffo.

it'll be wall-mounted suitable for 'continuous duty'.

Continous duty is exactly what you require.

i'm assuming just a c-type mcb and isolator for input.

Sounds good. I am guessing that you will have a mini 110 volt distribution board with protection 110 volt protection for each circuit? That is the way I would do it.

Is earth-fault protection required on 110v?

Yes. If it was 50V a.c. then it would be fall under section 414 of the regulations and an RCD would not be required. You will have 55V a.c per phase on the secondary side.

davelerave

Afaik the trafos are 1 or 2-phase input ,similar to welders.
http://www.blakley.co.uk/pdfs/TransPowerPDFs/TRPDS3_tdc_data_sheet.pdf
The 5kva has provision for 10 '16a circuits',so the trafos seem to be sized at 500va per 16a circuit.
They have only provision for 'rcd' ,afaik UK only requires rcd for outdoor equipment on the 110 circuits.

2011

I have seen large 3 phase 400/110 volt traffos on sites many times. They have an RCBO per outlet. I can see no reason not to use 3 phase.

It is possible to feed more than 10 sockets from a 5KVA transformer. I just think that 5KVA is a small transformer for 10 sockets. I would be a pain to be limited to what you can do in a workshop due to the transformer size.

davelerave

ya 3-phase trafo if available .
trafo may be bigger than 5kva depending on cost
it's 'D' type mcb on the supply side
http://www.blakley.co.uk/pdfs/TransPowerPDFs/Trans_Specification_and_Installation.pdf

2011

Sounds good.
The link is good also.

davelerave

suppliers all seem to have trafos with 1 or 2 phase input(230/380).3 phase is available but i assume it's prohibitively expensive

davelerave

quoted for 10kva as there was about 350 difference in price.
prob. separate 16a rcbo per socket due to higher current draw at 110v