Ring main in 4Core SWA

[TJC1]

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

 

[Lenny]

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

 

[davesparks]

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.

 

[Pete999]

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.

 

[davesparks]

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?

 

[Pete999]

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.
[automerge]1567538739[/automerge]


5 core plus earth or 4 core plus earth?

I meant 4 core plus cpc sorry mate my bad

 

[davesparks]

I meant 4 core plus cpc sorry mate my bad

I know you said that was in other countries, but it wouldn't comply here. BS7671 requires the cpc to be in the form of a ring with the exception of conduit/trunking used as the cpc.
I'm pretty sure this has been the way since at least the 16th edition.

 

[Pete999]

I know you said that was in other countries, but it wouldn't comply here. BS7671 requires the cpc to be in the form of a ring with the exception of conduit/trunking used as the cpc.
I'm pretty sure this has been the way since at least the 16th edition.

Just thought I would mention it that's all, not usual to use FP for general circuits is it? nore of a safety circuit type cable I thought. could be wrong though.

 

[davesparks]

Just thought I would mention it that's all, not usual to use FP for general circuits is it? nore of a safety circuit type cable I thought. could be wrong though.

Unfortunately it has become pretty common for FP200 to be used for general purpose wiring despite there being better, more suitable, alternatives available.

 

[Toneyz]

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.

Did you have CPC's or use the conduit as the circuit protective conductor?

 

[Pete999]

Did you have CPC's or use the conduit as the circuit protective conductor?

Was during a time wne cpc wasn't a normal phrase, as long as it was earthed nobody cred much, so it was the BE Conduit used as the cpc

 

[Toneyz]

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.

R1 + R2 based upon manufacturers information.
, can't really see any difference in MICC to SWA

Steel has a higher resistance than copper which will affect the maximum length of run for volt drop max ELI etc.

 

[Pete999]

Steel has a higher resistance than copper which will affect the maximum length of run for volt drop max ELI etc.

Yes ! ! ! ! ! !

 

[Dustydazzler]

I don’t see any value in wiring in rings through conduit

 

[Pete999]

I don’t see any value in wiring in rings through conduit

Why not ? ? ? ?

 

[Dustydazzler]

Why not ? ? ? ?

Because if I need a 30a supply I just pull in a 4mm radial , why bother with a ring...