Contactor---> Ring, wiring advice.

whproject · Oct 24, 2013

My apologies all, my post was of coarse missing some stuff, and rather confusing.

1. Are there any obvious rules preventing the use of ring circuits coming from a contactor like the one pictured below, it doesn't s seem there is.

2 Provided there are no restrictions preventing the use of a ring circuit with said contactor, is the wiring on the diagram correct.

This 2 pole contactor is of coarse capable of a 63A load at point 1 and point 3 simultaneously correct or have I misunderstood something, what I am asking is hypothetically if 50A rated wire was used in the rings.

Then each ring circuit would be happy to draw 39A limited by the 40A breaker on each leg, correct? putting a 78A total load on the contactor, this is of coarse hypothetical, I know them breakers shouldnt be put under 90%+ load for x hours etc, I just want to be sure I have a full understanding of the workings of this contractor.
Thank you for you're time.

Darkwood · Oct 25, 2013

Ive already noted the mcb rating and lack of rcd, the control from timer does not show how it is fused so can't comment the N don't need to be broken thus no need to run through contactor although its an option if you wanted to.

I can only assume the OP is learning possible early apprentice or DIY enthusiast due the set-up he chose to express his query and may not be an electrician although i will say he did express hypothetical but still to avoid critisism and create less confusion it would have been better with a standard circuit that complies as an example...

Pete999 · Oct 25, 2013

Explain please

tazz · Oct 25, 2013

Make the whole lot Din rail, using what Darkwood has explained

[ElectriciansForums.net] Contactor---> Ring, wiring advice.

whproject · Oct 25, 2013

Pete999 said:
Sorry, get the picture now, neutrals omitted I presume 2 x 40 amp RFC should be 32 amp cbs can't see any obvious flaws except the size of the cbs, what controls the coil?

The cbs will be 45A, the rings will be using 4mm rated at 32A and the draw on the rings will be well balanced/distributed along the ring, the rings load capacity will be safely over the 45A cbs, darkwood it will be an inductive load, but the 38A per ring will be on induction, I am 99.9% the ac3 rating of the contactor, (which I cant find) will be 50A+.

The wire from cbs to contactor will be 10mm rated at 55A

spark 68 · Oct 25, 2013

Pete999 said:
Explain please

Sorry I deleted my earlier post after seeing the edited OP, to clarify though, you can use a RFC for other uses other than Socket outlets.

Pete999 · Oct 25, 2013

But is a Ring Final Circuit as described in BS7671 designed for 13amp socket outlets, that is what the OP is on about isn't it?

spark 68 · Oct 25, 2013

Pete999 said:
But is a Ring Final Circuit as described in BS7671 designed for 13amp socket outlets, that is what the OP is on about isn't it?

Yes after editing his OP, but RFCs are not limited to 13A sockets in the industrial world, only in the domestic.

Pete999 · Oct 25, 2013

Can you give an example of a ring circuit in an industrial situation the only ones I personally have seen are to to with LV distribution systems is this what you mean?

spark 68 · Oct 25, 2013

Pete999 said:
Can you give an example of a ring circuit in an industrial situation the only ones I personally have seen are to to with LV distribution systems is this what you mean?

You can get 11kV Ringmains for a start, you might want to use a Ring Final circuit to connect a load of machine isolators up, it could depend on max cable sizes and circuit length for example, it may work out cheaper to install a ring distribution circuit.
There are many scenarios that could use ring circuits.

Pete999 · Oct 25, 2013

Agree with you but I'm a pedantic old fxxt and a ring final circuit as described in BS7671 is for 13amp socket outlets, maybe the phraseology used is confusing us both

spark 68 · Oct 25, 2013

Pete999 said:
Agree with you but I'm a pedantic old fxxt and a ring final circuit as described in BS7671 is for 13amp socket outlets, maybe the phraseology used is confusing us both

Sorry, you are mostly correct, a ring distribution circuit is not the same as a Ring final, but you can get 32A sockets and higher in industrial, which may use a RFC

Essential Supplies - Plugs, Sockets, Inlets and Couplers

whproject · Oct 25, 2013

Pete999 said:
Can you give an example of a ring circuit in an industrial situation the only ones I personally have seen are to to with LV distribution systems is this what you mean?

Light runs in green houses.
Having a control board with points for each light and then individually wiring every light back to the board 900ft away is not feasible would take MASSIVE amounts of cable, more feasible would be having a dtrbn Ring on LARGE CAPACITY contacts running the length of the light run from the control board. and controlling a few 100 lights per switch.

PS I dont think I said "ring mains" in any of my post, sorryy for the confusion.

Pete999 · Oct 25, 2013

No worries have a nice weekend, not too many beers mind
Pete999 TMIET

whproject · Oct 25, 2013

whproject said:
I need 38A per ring, of coarse there are plug sockets on teh ring, so my obvious option would be 4mm ring circuits, I will use 10mm rated at 55A from (45A mcb's) to contactor, this means each leg will start at a 45A breaker >>>55A cable to its own leg on the 63A contractor, to a ring of 4mm, rated at 32A, which will definitely have a higher capacity than the 45A breaker.

So just to summarise, bar the lack of RCD safety, using my diagram in the OP, with MCB and wire ratings from the above quote, this install would hypothetically, safely run 38A on each leg right.

Thank you all for you're time, and sorry for repeating myself and being annoying it's just of coarse I understand the seriousness and danger of electricity so just wanted to be 100% it would work (hypothetically of coarse)