Double insulated singles on 2 way switching

[stimpy]

As per title, d.I singles or 'insulated and sheathed singles' with no earth within cable and not run alongside any earths. What is the current view on these within an EICR?

There are earths at all the accessory and light points but i was always taught that every cable needed a cpc on the basis that if it did get cut then something would trip......

TIA

 

[HandySparks]

I don't think there's a problem. Can't think of a regulation requiring a cpc in every cable. The cpc may add a little extra safety to a cable in some circumstances, but that's not what it's there for.

After all, appliances can have flexible cables without a cpc and they're more likely to become damaged than fixed wiring. Plus, of course, meter tails don't have a cpc.

 

[Andy78]

543.6.1 may apply here. It's not a situation I have encountered before nor have heard of though. I can't imagine how the CPC is run if not with the live conductors or how you have verified this one way or the other.

 

[Jay Sparks]

Are the singles run in metal trunking/conduit? If so, is this used as the cpc?

Jay

 

[Richard Burns]

As a design now it is not a good arrangement (and would be difficult to arrange).
I would assume this is in relation to two wire two way switching of lighting where singles have been used to supply the switch and feed the light.
If the single core is adequately protected from mechanical damage and has been in place for a long time then there should be no significant risk and it would be a C3 or comment.
If the single is surface fixed or in an area likely to abrasion / impact then a recommendation would be to replace that cable with an earthed variety.
If there is a 30mA RCD in place then this would also reduce the risk of shock.

 

[Pete999]

As a design now it is not a good arrangement (and would be difficult to arrange).
I would assume this is in relation to two wire two way switching of lighting where singles have been used to supply the switch and feed the light.
If the single core is adequately protected from mechanical damage and has been in place for a long time then there should be no significant risk and it would be a C3 or comment.
If the single is surface fixed or in an area likely to abrasion / impact then a recommendation would be to replace that cable with an earthed variety.
If there is a 30mA RCD in place then this would also reduce the risk of shock.

Or you could use single insulated and sheathed, with an earth core, you used to be able to get it, not sure about now though,

 

[westward10]

Or you could use single insulated and sheathed, with an earth core, you used to be able to get it, not sure about now though,

You can but is rarely stocked, normally have to order it, reference code is 6241Y. As for the OP if all points are earthed where they need an earth I wouldn't worry about it.

 

[stimpy]

Thanks chaps,

Pretty much as i thought with the general views towards a C3. And yes these cables are existing in a domestic dwelling, have mechanical protection, switch boxes earthed by other cables and an rcd covering the lot. One would be unlikely to wire like this these days.

Thanks

 

[Risteard]

A few points:

Insulated and sheathed singles are readily available here.

There is no requirement for every cable to have a cpc - only that a cpc be terminated at every point of the wiring. (Otherwise singles would be unusable.)

No code is warranted or permitted as there is no non-compliance with BS7671.

 

[stimpy]

After all, appliances can have flexible cables without a cpc and they're more likely to become damaged than fixed wiring. Plus, of course, meter tails don't have a cpc.

However, Appliance cable atleast has a neutral so is 'likely' to trip / blow a fuse if damaged / cut. I'll grant you though that this whole debate is pretty grey and fundamentally also hinging on luck or bad luck of how you catch or damage the cable....

Hey ho....

 

[stimpy]

For reference i will be stating a C3 for it.

 

[Risteard]

For reference i will be stating a C3 for it.

On what grounds?

Can you provide a Regulation which is breached?

 

[westward10]

No Code required, you have stated what needs earthing is earthed. Unless these separately run cpcs are unenclosed and below 4.0mm csa.