Using earth as neutral

[Shpark]

We’ve pulled in a 185 cable just and realised that we need a neutral. It has 4 cores, brown, black, grey and earth. Can we use the earth as a neutral if we shrink wrap it with neutral sleeve and then run an earth separate? It’s a tri-rated cable, so no armoured to use as earth.

 

[davesparks]

If its tri rated then why not just pull a blue one in to the trunking?

 

[Spoon]

and then run an earth separate?

As above.... Why not just put in a neutral, instead of an earth?

 

[Pete999]

We’ve pulled in a 185 cable just and realised that we need a neutral. It has 4 cores, brown, black, grey and earth. Can we use the earth as a neutral if we shrink wrap it with neutral sleeve and then run an earth separate? It’s a tri-rated cable, so no armoured to use as earth.

Single or multicore cable, is it buried, in trunking or conduit, or clipped direct

 

[westward10]

It is tri-rated he is using incorrect terminology saying cable.

 

[davesparks]

Single or multicore cable, is it buried, in trunking or conduit, or clipped direct

Tri rated is flexible single insulated conductors.
Without further information I'd guess that for 185mm they'd be in trunking rather than conduit.

 

[Deleted member 26818]

Could be on ladder rack, or tray.
Yes you can over sleeve the earth core as neutral and pull in a separate earth.
The separate earth can then enter any ferrous magnetic enclosures separately from the 4 core, although doing such is only normally allowed for SWA cables.

 

[Shpark]

You’ll have to excuse me if I use the incorrect terminology. I’m basically an apprentice and have been set this as a task to find out. So it’s 4 core flexi I think they call it. Big thick black cable with no amouring, just 4 cores It’s runs under the floor and then up and onto ladder

 

[Deleted member 26818]

You can have multi core tri-rated cables.

 

[davesparks]

Could be on ladder rack, or tray.
Yes you can over sleeve the earth core as neutral and pull in a separate earth.
The separate earth can then enter any ferrous magnetic enclosures separately from the 4 core, although doing such is only normally allowed for SWA cables.

Now that we know its not actually tri rated cable yes, ladder or tray seems more likely.

There's an interesting debate to be had on whether it is ever allowed, for SWA or anything else.

 

[davesparks]

You can have multi core tri-rated cables.

I don't think so, tri rated cable is single core flexible cable to BS6231, UL and CSA standards

 

[davesparks]

You’ll have to excuse me if I use the incorrect terminology. I’m basically an apprentice and have been set this as a task to find out. So it’s 4 core flexi I think they call it. Big thick black cable with no amouring, just 4 cores It’s runs under the floor and then up and onto ladder

Flex is a very general term and could be any number of different cables, it may even not be a flexible cable at all and someone is just referring to it as such.

 

[Shpark]

Well I don’t know. I’ve pulled in a multi core this week and it was called tri-rated by all the sparks. I will picture it tomorrow

 

[Sintra]

Could possibly be a H07RN-F as a 4 core comes in brown, black, grey and green/yellow. IMO if it is an unarmoured multicore cable then the cpc needs to be within the cable hence why it is made with these coloured cores.

 

[rapparee]

Well I don’t know. I’ve pulled in a multi core this week and it was called tri-rated by all the sparks. I will picture it tomorrow

It's obviously a H07RN multicore.

 

[westward10]

Never heard of tri-rated flexible cable. There are rubber cables available in that size and if it is a long run someone has made a serious error.

 

[Deleted member 26818]

Now that we know its not actually tri rated cable yes, ladder or tray seems more likely.

There's an interesting debate to be had on whether it is ever allowed, for SWA or anything else.

Don’t understand why there’s any debate?
521.5.1 Ferromagnetic enclosures: electromagnetic effects
The conductors of an AC circuit installed in a ferromagnetic enclosure shall be arranged so that all line conductors and the neutral conductor, if any, and the appropriate protective conductor are contained within the same enclosure.
Where such conductors enter a ferrous enclosure, they shall be arranged such that the conductors are only collectively surrounded by ferromagnetic material.
These requirements do not preclude the use of an additional protective conductor in parallel with the steel wire armouring of a cable where such is required to comply with the requirements of the appropriate regulations in Chapters 41 and 54. It is permitted for such an additional protective conductor to enter the ferrous enclosure individually.

 

[rapparee]

Never heard of tri-rated flexible cable. There are rubber cables available in that size and if it is a long run someone has made a serious error.

It's called tri-flex


It's also mechanically strong.

I one time drove a genie MEWP over a live 50mm 5 core flex.

 

[PEG]

It's called tri-flex


It's also mechanically strong.

I one time drove a genie MEWP over a live 50mm 5 core flex.

I bet it looked like a snake,run over,on a cattle grid....

 

[Ian1981]

We’ve pulled in a 185 cable just and realised that we need a neutral. It has 4 cores, brown, black, grey and earth. Can we use the earth as a neutral if we shrink wrap it with neutral sleeve and then run an earth separate? It’s a tri-rated cable, so no armoured to use as earth.

If the cable is installed in some kind of metallic containment then use the containment as the cpc, size permitting of course.
S=K1/K2 x S/2