Site temps and discussion with other contractor

[robo83]

I've been discussing site temps with another contractor on site.

The supply is TNCS, there is a consumer unit in a fiberglass box which has its own rod (TT) and 2 Commando sockets and a double 230v external socket. All these are protected by the consumer unit in the fiberglass box The sockets are mounted externally on the framework.

There are 2 site containers. 1 of them has a Commando outlet on the side and is plugged into 1 of the Commando outlets near the consumer unit with SY cable, the other has a SY cable wired into the consumer unit of the container (toilets) and is plugged into the other Commando outlet. The SY cables are overhead with support by continarry wire.

I said the 230v double socket isn't allowed on site and the containers need to have their own earth rods. He has insisted the containers are temporary as on plugs and is responsibility of hire company for containers equipment. He has said he has only installed the commandos and 230v socket so tested back to them.

Am I wrong arguing these points.

 

[Pete999]

I've been discussing site temps with another contractor on site.

The supply is TNCS, there is a consumer unit in a fiberglass box which has its own rod (TT) and 2 Commando sockets and a double 230v external socket. All these are protected by the consumer unit in the fiberglass box The sockets are mounted externally on the framework.

There are 2 site containers. 1 of them has a Commando outlet on the side and is plugged into 1 of the Commando outlets near the consumer unit with SY cable, the other has a SY cable wired into the consumer unit of the container (toilets) and is plugged into the other Commando outlet. The SY cables are overhead with support by continarry wire.

I said the 230v double socket isn't allowed on site and the containers need to have their own earth rods. He has insisted the containers are temporary as on plugs and is responsibility of hire company for containers equipment. He has said he has only installed the commandos and 230v socket so tested back to them.

Am I wrong arguing these points.

Whats a Continarry wire?

 

[westward10]

There is no reason not to have a 230v socket provided it has additional 30ma rcd protection. The containers do not require their own electrodes and in fact do not have to be from a TT earthing system.

 

[cliffed]

May need to tt if metal containers.

 

[Martyn Fletcher]

Westward is indeed correct in what he says but there are several options for the given scenario according to 704.410.3.10 (page 222), although given the mention of a consumer unit by the OP are we led to assume an RCD is used?

 

[Nigel]

There is no reason not to have a 230v socket provided it has additional 30ma rcd protection. The containers do not require their own electrodes and in fact do not have to be from a TT earthing system.

In the scenario detailed they most certainly do need TT’ing.

Granted it is already done at the DB so no need to do it again.

 

[Nigel]

The installation is already TT’d so there is no need to install additional rods unless you are unhappy with the current TT arrangement.

The container company will only carry out dead tests at their warehouse so the containers will need to be properly tested when in their final position.

 

[westward10]

In the scenario detailed they most certainly do need TT’ing.

Granted it is already done at the DB so no need to do it again.

Why.

 

[Marvo]

The supply is TNCS, there is a consumer unit in a fiberglass box which has its own rod (TT)

If the supply is TN C S earthing arrangement and there's an additional earth spike at the CU this doesn't mean the installation becomes TT. The additional spike just becomes part of the PME.

 

[westward10]

It would be rare for a supplier to put in place a PME facility on a construction site so the OP may have misinterpreted the situation.

 

[Nigel]

Why.

PME earthing is not permitted under Section 704 or 717.

 

[Marvo]

Lol, I'm officially confused in that case, he did state the incoming supply as being TN C S... in which case a high liklihood of PME

 

[Nigel]

If the supply is TN C S earthing arrangement and there's an additional earth spike at the CU this doesn't mean the installation becomes TT. The additional spike just becomes part of the PME.

Agree but I read it as the PME stopped at that point and TT takes over(?)

 

[westward10]

Lol, I'm officially confused in that case, he did state the incoming supply as being TN C S... in which case a high liklihood of PME

I don't know the scale of the site but it would be highly unusual for a supplier to provide a TN-C-S earth for a construction site. The head may well have the facility to provide it but is is likely to be not used so an electrode would have to be employed.

 

[Deleted member 26818]

If this is a Construction site, then PME is not permitted.
As such, it is quite likely that the rod has been installed to provide TT earthing.
230V and even 400V is allowed on construction sites in some circumstances, offices, dedicated supplies to certain equipment, etc.
There should be no 230V general use sockets out on site.

 

[Nigel]

It would be rare for a supplier to put in place a PME facility on a construction site so the OP may have misinterpreted the situation.

Doesn’t have to be a purposly installed supply for a construction site.

 

[westward10]

Doesn’t have to be a purposly installed supply for a construction site.

??

 

[Marvo]

Agree but I read it as the PME stopped at that point and TT takes over(?)

I read it differently but you almost certainly right given there's regs preventing the PME being utilised.

 

[Martyn Fletcher]

Lol, I'm officially confused in that case, he did state the incoming supply as being TN C S... in which case a high liklihood of PME

That's an assumption I would have made. Making the whole scenario odd from the outset.

 

[Nigel]

It would be rare for a supplier to put in place a PME facility on a construction site so the OP may have misinterpreted the situation.

Doesn’t have to be a purposly installed supply for a construction site.

??

You are assuming it is a purposely installed supply for a construction site.

It could be a refurb or a partial demolition and rebuild that is utilising the old supply.