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Buzz Lightbulb

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Gentlemen,

I am adding a new ring and lighting circuit to an integral garage. I'll be taking a 2.5mm t&e cable from a 32A MCB at the main CU into the garage via underfloor, to a small remote CU (20A ring, 6Amp lighting mcb's) in the garage. The main CU will give RCD protection to the whole circuit. I was planning to run the ring in the garage with single core in conduit, but what size would you recommend for the phase, neutral and earth? Also, a friend of mine said I should also supp bond the gas central heating boiler that sits in the garage as well. (There is good main and supp bonding already in the house itself) Would you say doing this is necessary?

I may use this small project for my assessment with ElecSa.
Be grateful for any views/advice chaps.
Cheers
Buzz
 

ian.settle1

-
Mentor
Arms
Gentlemen,

I am adding a new ring and lighting circuit to an integral garage. I'll be taking a 2.5mm t&e cable from a 32A MCB at the main CU into the garage via underfloor, to a small remote CU (20A ring, 6Amp lighting mcb's) in the garage. The main CU will give RCD protection to the whole circuit. I was planning to run the ring in the garage with single core in conduit, but what size would you recommend for the phase, neutral and earth? Also, a friend of mine said I should also supp bond the gas central heating boiler that sits in the garage as well. (There is good main and supp bonding already in the house itself) Would you say doing this is necessary?

I may use this small project for my assessment with ElecSa.
Be grateful for any views/advice chaps.
Cheers
Buzz

2.5mm is to small for a 32A MCB, should be either 4mm or 6mm for that sized MCB
 
Gentlemen,

I am adding a new ring and lighting circuit to an integral garage. I'll be taking a 2.5mm t&e cable from a 32A MCB at the main CU into the garage via underfloor, to a small remote CU (20A ring, 6Amp lighting mcb's) in the garage. The main CU will give RCD protection to the whole circuit. I was planning to run the ring in the garage with single core in conduit, but what size would you recommend for the phase, neutral and earth? Also, a friend of mine said I should also supp bond the gas central heating boiler that sits in the garage as well. (There is good main and supp bonding already in the house itself) Would you say doing this is necessary?

I may use this small project for my assessment with ElecSa.
Be grateful for any views/advice chaps.
Cheers
Buzz
hi,
I recon you should be coming from a 20amp in the house.
Your singles should be 2.5,2.5,and either 1.5 or 2.5 for earth.
I think T&E would be cheaper though.And likely that a radial would do your job instead of a ring.
As for your boiler you should check for sound continuity before deciding if you need additional bonding.
 
B

Buzz Lightbulb

  • Thread Starter Thread Starter
  • #4
OK thanks chaps. I took the 2.5 mm from OSG Table 7.1 so assumed it would be up to the job?

I think the idea of the radial rather than ring is a good one as I'll only be putting a max of 3 X double sockets in. The remote CU will of course feed sockets and lighting so that's why I thought 32A from main CU (into a 20A breaker for sockets and 6 A breaker for lights = 26A total)

Just stroke my confidence will you with any thoughts again thank you very much!
 
S

Spudnik

  • Thread Starter Thread Starter
  • #5
OK thanks chaps. I took the 2.5 mm from OSG Table 7.1 so assumed it would be up to the job?

I think the idea of the radial rather than ring is a good one as I'll only be putting a max of 3 X double sockets in. The remote CU will of course feed sockets and lighting so that's why I thought 32A from main CU (into a 20A breaker for sockets and 6 A breaker for lights = 26A total)

Just stroke my confidence will you with any thoughts again thank you very much!


2.5 cable is rated at around 26A, so it should be protected by an MCB less that its CCC, in this case, 20A MCB from main CU.

If you wish to have 32A from the main CU, then, depending on various installation factors you must use either 4mm or 6mm.

I have to be honest, this is really basic stuff which you would have been taught on whatever course(s) you have done but, if you need to ask, maybe you should put off your assessment if you have booked it.
 
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