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TJC1

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Evening all

Has anyone ever wired a ring main in 4Core SWA and used the sheath as an earth?

Just looking at wiring some sockets in an industrial unit and wondering whether to do it that way or do a 4mm radial
 
I have extended an existing ring in 4 core MICC before just to keep the number of visible cables to a minimum in a listed building. But I wouldn't design and install a complete new circuit this way,it seems to defeat the point of a ring to me.

Why do you think that would be a good design for this particular job?
 
Used To do it that way using MICC

What was the logic behind wiring a ring and not a radial?
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not many sparks can play with that or shown its all FP2000 stuff .still go me old tools .

FP200 for fire alarms etc yes, or bs8436 cable for general purpose circuits. MICC is just too expensive these days to be economical for general use and the other types of cables satisfy the requirements most of the time.
I still work with MICC and install it new as and when it is required for the job, but that's just not very often these days.
 
What was the logic behind wiring a ring and not a radial?
Not sure it was just the way we used to do it on some jobs, it's basically the same way as using conduit and singles, one run of tube no return to the CU and no connectors in the socket back box, as you would use if you used 4 core SWA or MICC.
 
Not sure it was just the way we used to do it on some jobs, it's basically the same way as using conduit and singles, one run of tube no return to the CU and no connectors in the socket back box, as you would use if you used 4 core SWA or MICC.

To my mind it just doesn't seem logical, whether it's in conduit or cable, to run a ring in such a way when you're pretty much cabling it as you would a radial.
 
Not sure the armoured would have enough CCC for a good enough earth loop impedance. I can see hoe micc would have though.
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To my mind it just doesn't seem logical, whether it's in conduit or cable, to run a ring in such a way when you're pretty much cabling it as you would a radial.
Agree it doesn’t seem logical for Cable but conduit is normal practice.
 
To my mind it just doesn't seem logical, whether it's in conduit or cable, to run a ring in such a way when you're pretty much cabling it as you would a radial.
Some designers demanded that it should be a RFC
 
Agree it doesn’t seem logical for Cable but conduit is normal practice.

Is it? I don't think I've ever wired a ring this way in conduit where the conduit is a single run via all the sockets, say along a wall.

Obviously where the conduit is part of a wider conduit and trunking system it often does make sense to wire as a ring.
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Some designers demanded that it should be a RFC

Ah I see, so its more likely a case of 'ring = sockets, therefore sockets = ring' attitude than a reasoned technical consideration.
 
Not sure it was just the way we used to do it on some jobs, it's basically the same way as using conduit and singles, one run of tube no return to the CU and no connectors in the socket back box, as you would use if you used 4 core SWA or MICC.
Actually when this sort of thing was the, norm and in some cases still is, there were some Sparkies who found it very difficult to understand hoe to do it with both 4 core and conduit, maybe they still are, who knows, I met a few in my time. I enjoyed the conduit method, the only drawback was you nee.ded six drums of cable to do it economically
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Is it? I don't think I've ever wired a ring this way in conduit where the conduit is a single run via all the sockets, say along a wall.

Obviously where the conduit is part of a wider conduit and trunking system it often does make sense to wire as a ring.
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Ah I see, so its more likely a case of 'ring = sockets, therefore sockets = ring' attitude than a reasoned technical consideration.
Think about it, if you have to run some tube along a long run from the DB on a nice clean wall, would you want to run Conduit from socket to socket, an\n then run another tub \e from the last socket on the run back to the DB? clearly not if you have wits about, different picture if you have other trunking or Conduit available to use for the return leg.
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What was the logic behind wiring a ring and not a radial?
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FP200 for fire alarms etc yes, or bs8436 cable for general purpose circuits. MICC is just too expensive these days to be economical for general use and the other types of cables satisfy the requirements most of the time.
I still work with MICC and install it new as and when it is required for the job, but that's just not very often these days.
Nave wire RFCs in 5 core FP 200 the same way as if using MICC in overseas locations, not in the UK I hasten to add.
 
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Why or what information do you have to back up that theory that MICC sheathing would be sufficient as a cpc for this method of wiring.
I ask because when, in the distant past we used MICC 4 core for RFCs it was a case of just use it, it was the norm to do so, can't really see any difference in MICC to SWA after all people now pay more attention to cable, and cpc sizing these days, I personally think that providing the cable is sized and installed correctly there shouldn't be a problem, bur testing will confirm, of course if you are only experienced in PVC/PVC cable all this chit chat may be of little interest, until of course you come across it in your line of expertise.
 
Hi.

The list below gives the physical CSA of MICC copper sheath when its used as a cpc.

Hope it's of use.

2L1 ****** 5.4 mm2
3L1 ****** 6.7mm2

2L1.5 ****** 6.3 mm2
3L1.5 ****** 7.8 mm2
4L1.5 ****** 9.1 mm2


2H1.5 ****** 11 mm2
3H1.5 ****** 12 mm2
4H1.5 ****** 14 mm2


2L2.5 ****** 8.2 mm2
3L2.5 ****** 9.5 mm2
4L2.5 ****** 11 mm2

2H2.5 ****** 13 mm2
3H2.5 ****** 14 mm2
4H2.5 ****** 16 mm2

2L4 ****** 11 mm2
2H4 ****** 16 mm2

2H6 ****** 18 mm2
3H6 ****** 20 mm2

2H10 ****** 24mm2
3H10 ****** 27mm2

2H16 ****** 30mm2
3H16 ****** 34mm2
 
Think about it, if you have to run some tube along a long run from the DB on a nice clean wall, would you want to run Conduit from socket to socket, an\n then run another tub \e from the last socket on the run back to the DB?

Of course not, there's no need for a run back to the board, I just wouldn't wire the sockets as a ring in this situation. I would run a radial as there is no advantage to using a ring, so the disadvantages of a ring would outweigh the advantages in this instance in my opinion.
 
Why or what information do you have to back up that theory that MICC sheathing would be sufficient as a cpc for this method of wiring.
I ask because when, in the distant past we used MICC 4 core for RFCs it was a case of just use it, it was the norm to do so, can't really see any difference in MICC to SWA after all people now pay more attention to cable, and cpc sizing these days, I personally think that providing the cable is sized and installed correctly there shouldn't be a problem, bur testing will confirm, of course if you are only experienced in PVC/PVC cable all this chit chat may be of little interest, until of course you come across it in your line of expertise.
Hi.

The list below gives the physical CSA of MICC copper sheath when its used as a cpc.

Hope it's of use.

2L1 ****** 5.4 mm2
3L1 ****** 6.7mm2

2L1.5 ****** 6.3 mm2
3L1.5 ****** 7.8 mm2
4L1.5 ****** 9.1 mm2


2H1.5 ****** 11 mm2
3H1.5 ****** 12 mm2
4H1.5 ****** 14 mm2


2L2.5 ****** 8.2 mm2
3L2.5 ****** 9.5 mm2
4L2.5 ****** 11 mm2

2H2.5 ****** 13 mm2
3H2.5 ****** 14 mm2
4H2.5 ****** 16 mm2

2L4 ****** 11 mm2
2H4 ****** 16 mm2

2H6 ****** 18 mm2
3H6 ****** 20 mm2

2H10 ****** 24mm2
3H10 ****** 27mm2

2H16 ****** 30mm2
3H16 ****** 34mm2
Thanks for that Mate, will come in handy.
 
Why or what information do you have to back up that theory that MICC sheathing would be sufficient as a cpc for this method of wiring.

Generally the CSA of the sheath is over twice the CSA of one conductor in multicore MICC so will always automatically comply as a CPC.
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Nave wire RFCs in 5 core FP 200 the same way as if using MICC in overseas locations, not in the UK I hasten to add.

5 core plus earth or 4 core plus earth?
 
Generally the CSA of the sheath is over twice the CSA of one conductor in multicore MICC so will always automatically comply as a CPC.
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5 core plus earth or 4 core plus earth?
I meant 4 core plus cpc sorry mate my bad
 

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