Single Insulated Meter Tails

[micklmas]

Hi everyone,

I'm new to this place and only doing my training at the moment.

The guy I'm working with and me are currently on a job where we are wiring up to a meter. The meter tails are double insulated and are about 300mm long. They are connected into a fused isolator in the meter box.

What the guy I'm working with is intending to do is run single insulated cables from the isolator to the consumer unit which is about 10 meters away. He says that single insulated is allowed if we enclose them in conduit. We have a load of 25mm plastic stuff in the van that we are going to use.

I thought that the cables would need to be double insulated all the way to the consumer unit, but he disagrees.

So who is right?

 

[Trevle]

Only problem I see is getting meter tails into 25mm conduit or trunking.

 

[Leesparkykent]

Listen to your mentor/the guy you are working with as he is correct, if enclosed in conduit from switch fuse to consumer unit.

Could be better options though of doing it like in T+E (depending on size/installation method) or swa for example.

 

[shanky887614]

Hi everyone,

I'm new to this place and only doing my training at the moment.

The guy I'm working with and me are currently on a job where we are wiring up to a meter. The meter tails are double insulated and are about 300mm long. They are connected into a fused isolator in the meter box.

What the guy I'm working with is intending to do is run single insulated cables from the isolator to the consumer unit which is about 10 meters away. He says that single insulated is allowed if we enclose them in conduit. We have a load of 25mm plastic stuff in the van that we are going to use.

I thought that the cables would need to be double insulated all the way to the consumer unit, but he disagrees.

So who is right?

is it surface? if not then it wont be allowed as no rcd protection

 

[davesparks]

Hi everyone,

I'm new to this place and only doing my training at the moment.

The guy I'm working with and me are currently on a job where we are wiring up to a meter. The meter tails are double insulated and are about 300mm long. They are connected into a fused isolator in the meter box.

What the guy I'm working with is intending to do is run single insulated cables from the isolator to the consumer unit which is about 10 meters away. He says that single insulated is allowed if we enclose them in conduit. We have a load of 25mm plastic stuff in the van that we are going to use.

I thought that the cables would need to be double insulated all the way to the consumer unit, but he disagrees.

So who is right?

The meter tails aren't double insulated, they are insulated and sheathed. The outer layer is a sheath intended to give mechanical protection to the insulation layer beneath.
Conduit provides mechanical protection to the cables inside it so unsheathed cables are used.

 

[Engineer54]

Listen to your mentor/the guy you are working with as he is correct, if enclosed in conduit from switch fuse to consumer unit.

Could be better options though of doing it like in T+E (depending on size/installation method) or swa for example.

Do you really consider T&E a better option than tails and main earth in a correctly sized PVC conduit, i certainly don't??

 

[micklmas]

Thanks for all the replies.

is it surface? if not then it wont be allowed as no rcd protection

We were intending to run the conduit above ground.

So as an alternative, if we ran armoured cable below ground instead, it would need RCD protection?

 

[Bobster]

If you ran the tails in earthed metallic conduit you wouldn't need an RCD, unless it's a TT system. The you will need a 100mA S type to cover earth fault protection.

 

[Engineer54]

Thanks for all the replies.



We were intending to run the conduit above ground.

So as an alternative, if we ran armoured cable below ground instead, it would need RCD protection?

I hope you are talking about an appropriately sized 3 core SWA and NOT a two core SWA?? And no you wouldn't need an RCD protection, unless the installation is sourced from a TT supply....

 

[Leesparkykent]

Do you really consider T&E a better option than tails and main earth in a correctly sized PVC conduit, i certainly don't??

I do see what you mean depending on the size of the tails though as the OP said 25mm conduit. Either way is fine IMO.

edit: Just seen the OP's other post, My preferred method would be SWA in his situation.

 

[davesparks]

Thanks for all the replies.



We were intending to run the conduit above ground.

So as an alternative, if we ran armoured cable below ground instead, it would need RCD protection?

armoured cable below ground would not normally need RCD protection, the exception being a TT system with a poor Ra.

In your situation RCD protection would be required if the conduit is buried in the wall at a depth of less than 50mm and is in a safe zone. Outside of a safe zone or without RCD protection it would require further mechanical or earthed metallic protection.

 

[7029 dave]

Metal trunking, not for this situation but is an good method.

 

[shanky887614]

Thanks for all the replies.



We were intending to run the conduit above ground.

So as an alternative, if we ran armoured cable below ground instead, it would need RCD protection?

swa doesnt need an rcd

 

[davesparks]

swa doesnt need an rcd

Except when it does