2 x t&e for 3 phase isolator

kev.k · Sep 20, 2024

Hi All!

Came across this yesterday and just wanted to get others opinion. 3 phase isolator wired in 6mm twin and earth x 2, i'm guessing it's not against regs? Obviously not the best way to do it but would anybody pull this on EICR? It's wired in 25mm pvc conduit on 32a breaker, assume they couldn't be bothered going wholesalers for some 5 core SWA.

Thanks

[ElectriciansForums.net] 2 x t&e for 3 phase isolator

westward10 · Sep 20, 2024

Definitely needs a note see Regulation 521.8.1.

Marvo · Sep 20, 2024

Are the cables the same CSA? maybe it's just the photo but they look like different types of cables to me....

kev.k · Sep 20, 2024

Marvo said:
Are the cables the same CSA? maybe it's just the photo but they look like different types of cables to me....

Yes both are definitely 6mm t&e, one of them has a darker grey outer insulation than the other so just not from the same drum/manufacturer

Rockingit · Sep 20, 2024

It’s a C3. Somewhere in the regs (I would have to have a copy with me to remind myself where!) there is commentary that all line conductors have to be within the same overall sheath/mech protection. The reason being is that by having effectively 2x together and 1x separate they will have heat dissipation at different rates, therefore different resistances.

Apart from being dog rough.

MDJ · Sep 22, 2024

Terrible IMO, just Terrible.

PS Electrics · Sep 22, 2024

MDJ said:
Terrible IMO, just Terrible.

It is a ---- poor bit of work and really ought to be corrected.

cireland · Sep 23, 2024

Are they not in the same conduit? Does that mean it isn't a code?

PS Electrics · Sep 24, 2024

Henryko said:
Hey! Yeah, it’s not ideal, but I don’t think it’s breaking any regs either. The twin and earth in conduit should be fine for the 32A breaker. Wouldn't pull it on an EICR myself.

Technically it does as Westward eluded to "Definitely needs a note see Regulation 521.8.1." Also this has come up here a few years ago and the same Reg was mentioned then. I don't have the book to hand to check it but would trust it is correct.

DefyG · Sep 25, 2024

Came across 3No 1ph heaters connected by 2xT&E cables from a 3phase supply on an installation whilst carrying out an EICR few years back.
Effectively carried out a 'FI (Further Investigation)' at the time to establish what had been done as not immediately obvious. - 3 identical heaters so balanced load, 1core of 1 t&e acting as neutral for the 3ph, and ccc large enough should only 2 heaters be used at any one time. Unable to establish cable routes but R1+R2 test concurred cables to be of identical length.
Nothing immediately dangerous although not compliant so declared C3.

As for original post, if all within conduit then no code! but labelled per #2