Circuits earthed on metal box/conduit: Does it need a rewire?

[littlespark]

If surface, the conduit might connect directly to the consumer unit... hopefully all from one direction.

If the conduit is buried behind the CU, it might terminate into a large square metal box with the CU in front, relying on just the fixing screws holding the CU onto the box. A big enough earth wire may need to attached to the box and brought into the new CU in addition to this.

 

[westward10]

Wouldn't that connection need to be maintenance free

 

[Ratmeister]

If surface, the conduit might connect directly to the consumer unit... hopefully all from one direction.

If the conduit is buried behind the CU, it might terminate into a large square metal box with the CU in front, relying on just the fixing screws holding the CU onto the box. A big enough earth wire may need to attached to the box and brought into the new CU in addition to this.

It's all surface conduit thoughout the building and surface conduit running to the CU. It's a different type of conduit beside the CU that is older and isn't in as good a condition though. Would the worst case scenario be that a new earth cable is needed to the better condition conduit? (Building was wired in different stages) Or is there any scenario at all where he is correct and it needs rewired?

 

[Ratmeister]

Wouldn't that connection need to be maintenance free

Hi Westward, can you explain a bit more if you have time?

 

[littlespark]

No need to rewire IF the existing cables are in good condition.

It MAY need a partial rewire, in as much as running in an earth wire through the conduit.... but it all depends on how bad the older part of conduit is.... which is why we suggested testing first.

 

[Ratmeister]

No need to rewire IF the existing cables are in good condition.

It MAY need a partial rewire, in as much as running in an earth wire through the conduit.... but it all depends on how bad the older part of conduit is.... which is why we suggested testing first.

Sorry if I'm picking this up wrong, but could we bypass the older conduit with a new earth wire that just connects the CU direct to the newer conduit?

 

[davesparks]

Or is there any scenario at all where he is correct and it needs rewired?

If the existing cable is damaged or deteriorated then it may need to be rewired for that reason.

But there is no need to rewire it for not having a seperate earth in there. The worst case scenario for that would be adding an earth wire into the conduit in any part where it is required.

 

[davesparks]

Sorry if I'm picking this up wrong, but could we bypass the older conduit with a new earth wire that just connects the CU direct to the newer conduit?

You wouldn't bypass it, you would run the earth inside the conduit.

 

[Ratmeister]

You wouldn't bypass it, you would run the earth inside the conduit.

Yep, but I mean you would be bypassing it's use as an earth? And just using the older section purely for holding the new cable?

 

[James]

Wouldn't that connection need to be maintenance free

Only if it is not accessible.
or at least that is my humble opinion.