Ring lighting circuit

[Gavthesparky]

Working on a job this week where the lighting circuit was a ring of 1.5mm on a 6a MCB with the individuals room circuits effectively been spurred off the ring. Two things sprang to mind, is this compatible with 17th edition as I cannot find any direct reference to it, and secondly it must be a good way to keep voltage drop down to a minimum on a lengthy lighting run without having to go up to 2.5?

Any feedback is welcome.

 

[roukel01]

you can have a 90 meter run on a 6amp mcb using 1.5mm, so its gonna have to be a fairly large lighting circuit to justify using anything else.

Only time I've seen a lighting circuit wired as a ring is for floodlights on a sports field, and that was to try and reduce voltage drop on the large cable runs.

I don't suppose it is a deviation from regs as long as its wired correctly. and it all tests out ok

 

[Gavthesparky]

Thanks for the reply. The cable lengths were not so long but there were a number of mains downlighters so I image the ring was to compensate for the power usage.

 

[Markc]

I’ve seen this hundreds of times in the retail sector (Shop fitting) Large department stores are wired in this manner sometimes and most times way over your 6amp. I’ve seen one at 63amps! (we did rip that out in the course of our works) It’s not a preferred wiring method but it can be calculated by the regs and cable calculations. One advantage over sockets is that you have a fixed load so can calculate the total demand accurately.
Is it against the reg’s. Not if its been designed and calculated accordingly. Would I wire one like this No. Contactors and individual fuse carriers on all fittings in my book but I know people with disagree with that.

 

[sparks1234]

I know people with disagree with that.

Totally

 

[pennywise]

Non standard wiring techniques causes accidents, totally agree too.

 

[Markc]

Non standard wiring techniques causes accidents, totally agree too

Puzzled over response to my last post and after reading I see why! I possibly made it sound that I would wire a ring lighting circuit or wire a high ampere circuit and allow for protection on individual fittings. Sorry didn’t mean to sound like that.

I did say “would I wire a lighting circuit in a ring, No” I would not and haven’t but have removed lot’s in my time. When I was in the shop re-fit market I travelled the country. I works in lot’s of high street chains, Clinton Cards, Mother Care, Debenhams, Boots just to name a few. Our works always involved replacing light fittings and adding till points. The lighting circuits were always totally re-wired as in the main they where totally knacked. Cables strung, flung across ceilings, heated up beyond believe and breaking down but as this was retail and the big wigs in the suites only interested in return per sq foot of retail floor space then it never got high on their list of requirements.

Our works always used calculated radial circuits and never rings for lights. Normally 1.5, 2.5mm or some times 4.0mm normally FP or LSF T&E but that was rear. Switching was via contactors, Contactor feeding a designated lighting board or radio switches (mother care can still turn their entire network off at same time form their HQ for example). We used to fit 1 or 2amp fuse and carrier inside any fitting that didn’t come manufactured with one. The thinking was to safe guard against total circuit loss if one fitting went to fault.

Mecca (the bingo hall’s and not the place!) have 600 x 600 layin fittings, four tube and 2 Phase, 400V inside the same fitting. Two tubes on one phase and two on the second. No labels warning of such and it caught me out the first time I saw one. Never seen them any where else to date and when I asked about the thinking behind them (Apart from killing a electrician or maintenance man) their response was “If we lost a phase we can keep trading as we will still have some lights on”

I hope I’ve cleared that up.

Cheers

 

[Notsosmart]

Non standard wiring techniques causes accidents, totally agree too
Mecca (the bingo hall’s and not the place!) have 600 x 600 layin fittings, four tube and 2 Phase, 400V inside the same fitting. Two tubes on one phase and two on the second. No labels warning of such and it caught me out the first time I saw one. Never seen them any where else to date and when I asked about the thinking behind them (Apart from killing a electrician or maintenance man) their response was “If we lost a phase we can keep trading as we will still have some lights on”

My response to that would be that why not wire alternate fitting across the phases then?