Is this allowed as i could not find an answer in the wiring regs.

[DavidS]

4 core, 10mm SWA cable feeding a trace heating installation. The Installer has stated he wants to use 2 cores as 2 phases and 2 cores as Neutrals. This means the cable will have 2 separate circuits within. This would be acceptable if installed within conduit, but is this classed as bad practice within a cable??

 

[James]

I see no problem, as long as it’s marked correctly.

I wouldn’t call it bad practice either, efficient use of time and materials.
Be careful about method of isolation etc. And warning notes.

 

[Andy78]

My first thoughts would about adequate isolation of the circuits and the size of the cpc.

 

[DavidS]

I see no problem, as long as it’s marked correctly.

I wouldn’t call it bad practice either, efficient use of time and materials.
Be careful about method of isolation etc. And warning notes.

Thanks James, that was my first thought to have correct identification of 2 ccts at both ends.
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Thanks James, that was my first thought to have correct identification of 2 ccts at both ends.
Source URL: Is this allowed as i could not find an answer in the wiring regs. - https://www.electriciansforums.net/threads/is-this-allowed-as-i-could-not-find-an-answer-in-the-wiring-regs.179402/#post-1580921

 

[DavidS]

My first thoughts would about adequate isolation of the circuits and the size of the cpc.

Thanks Andy, good shout on the cpc. May require a separate earth if armour is not sufficient.

 

[telectrix]

Thanks Andy, good shout on the cpc. May require a separate earth if armour is not sufficient.

only for bonding purposes on a TNC-S. . it's adequate as a cpc, bear in mind that if you have 415V between conductors in the same cable, each conductor insulation rating must be > 415V.

 

[Dustydazzler]

No difference than multiple circuits in trunking or conduit

Labelling will be very important as will identification of cores

 

[Lucien Nunes]

Make sure to correct the CCC as 2 circuits. Iz will probably work out lower than for one 3-phase 4-wire circuit as in that case theoretically no more than 3 out of 4 cores can be fully loaded (ignoring 3rd harmonic.)

 

[westward10]

Whilst I understand correct identification of conductors there is no requirement for any warning notices/labels.

 

[James]

Whilst I understand correct identification of conductors there is no requirement for any warning notices/labels.

Not even if they are powered from different supplies?
Isolate at more than one point type note on panel door?

Might not be a requirement but good practice where you think it is necessary.

 

[westward10]

They aren't from different supplies just different circuits.

 

[SheffSimon]

What has the method of cabling got to do with the method of isolation?

 

[Gavin Price]

Nothing wrong with it. Regulation 521.7 allows it as long as the requirements of regulation 528 are meant which is regarding to the proximity of other electrical and non electrical services . The only reason I know is because I carried out an EICR and had a cable with multiple circuits and questioned it myself.

 

[davesparks]

4 core, 10mm SWA cable feeding a trace heating installation. The Installer has stated he wants to use 2 cores as 2 phases and 2 cores as Neutrals. This means the cable will have 2 separate circuits within. This would be acceptable if installed within conduit, but is this classed as bad practice within a cable??

Yes perfectly acceptable, it is quite clear in the regulations along with clear guidance on the applicable grouping factor.
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Not even if they are powered from different supplies?
Isolate at more than one point type note on panel door?

Might not be a requirement but good practice where you think it is necessary.

If they are from different supplies then that would be a very different thing to just having two circuits from the same supply.

No there isn't any need for labels or notices, if there was then you'd have to start labelling every conduit, trunking, joint box, grid switch etc etc.
Plus if course there's the fact that labels and notices achieve nothing, people don't read them or take any notice of them if they do.

 

[Sparks415]

Thanks Andy, good shout on the cpc. May require a separate earth if armour is not sufficient.

You can buy 5 core armoured also,very expensive.