Main bonding at outbuilding

[Darkwood]

If the SWA has the additional capacity to cover the bonding as well as serve the earthing requirements of the submain it can be used (unlikely if your equip' bonding is 50mm), if it can't you need to run the full requirements of the earth bonding as an additional cable and not a csa that only makes up the shortfall. Also you can use structural steel as a bonding path and link other services to it as long as it is suitably sized to meet the copper - steel comparison as well as been structurally sound through out its length to your primary structural bonding point from the MET.

 

[Jimmyb]

I always thought for a tncs/pme the steel couldn't be used, got me think now

 

[Darkwood]

Im not aware why it can't be used if its size and structural integrity are sound then why not? Its a conductive path of suitable low impedance and structurally solid.

 

[davesparks]

Steel armour can be used for bonding on tncs but you have to consider the heating effect of diverted neutral currents flowing through the armour as this will affect the cables ccc .

 

[Engineer54]

Im not aware why it can't be used if its size and structural integrity are sound then why not? Its a conductive path of suitable low impedance and structurally solid.

Let's just say it's one big MET!! ...lol!!

 

[Engineer54]

Steel armour can be used for bonding on tncs but you have to consider the heating effect of diverted neutral currents flowing through the armour as this will affect the cables ccc .

Can, but will be extremely rare, considering the CSA of the steel armouring needs to be multiplied by 8 X that of copper, ...you'll virtually never see it being used beyond that of a cables CPC...

Why would diverted neutral currents (which will only be seen at time of a fault) flowing in the armouring affect the design CCC of a cable??