Bonding Frame of External Garage

[murphy4869]

I have a detached concrete garage which is supplied, electrically, by 10mm swa on a 40 amp MCB from the house CU into the garage CU.

The roof is supported by a steel frame which is exposed inside, is this classed as an extraneous conductive part, therefore would it be advised to bond this with 10mm earth cable back to the CU?

Thanks

 

[ricicle]

Does this steel frame just sit on top of the walls or does it go in to the ground?
What type of earthing arrangement do you have at your house mains?
How is the earth provided at the garage?

 

[murphy4869]

the frame sits on top of the concrete panels, house is supplied by earth at main incoming cable, TNS i think???? Then the garage receives it's earth via one of the SWA cores from the house earth in the CU. The run is approx 5 metres from house

 

[ricicle]

There is no need to bond the frame as it is not likely to introduce a potential from outside.

 

[murphy4869]

ok thanks very much,

 

[Pensdown]

There is no need to bond the frame as it is not likely to introduce a potential from outside.

Although I agree it may not be an extraneous conductive part I'm not sure if it's that cut & dry?

It's not easy to run cables inside concrete garages so most people cable tie the cabling to the steel work. If that's the case, the steel work could become an exposed conductive part.

If that is the case it may require earthing.

 

[murphy4869]

thanks pendown, this is indeed the case i have the 2.5mm T&E tied to the steel frame and then drops to the power sockets.