Replacing broken junction box outside

[Steve T]

Hi

I’ve got a junction box outside which is cracked. It has 3 1.5mm SWA cables going into it.
I’m planning on replacing it with a Wiska 308 box, with piranha earth nuts. In the old junction box the SWA was not earthed-banjos attached but no earth fly lead.
I’ve got two questions about installing the new junction box:
1) What CSA should the earth fly lead from the piranha earth nuts be?
I’m guessing it should be the copper equivalent to the CSA of the steel armour, but I’m struggling to find this information!
2) Would you put ‘magic gel’ in the junction box, in case of condensation?
Thanks for any replies

 

[buzzlightyear]

why don't you use a galv box instead of plastic?

 

[Steve T]

Forgot to mention there are also two 1mm flex in the junction box, so 5 cables in total. Think that’s too many for a galv box.

 

[Octopus]

Not sure the whisks boxes will accept piranha nuts.

Wagon earth bars are far better

 

[Steve T]

Not sure what you mean by ‘wagon earth bars’, searched that and nothing came up. Could you post a link?

 

[Octopus]

Dam predictive text ... sorry Wiska earth bar

TLC code wk ec308

 

[Steve T]

Thanks, what CSA cable should I use to connect to the earth bar?
I’m struggling to find out what the copper equivalent is to the CSA of the steel armour.

 

[Baker1988]

If it is 1.5mm swa then just use 1.5mm for the fly lead.

 

[Richard Burns]

You will have a lot of fun terminating five different cables into a 308 JB without it looking like a rats nest.
The wiska boxes are designed not to accept standard components for SWA so you have to buy the earthing bar; that does not seem to be available for any other size box than the 308, though I have probably just missed them.
The copper equivalent of the armour is about 6mm², but the maximum size you will need will be the csa of the cpc for the circuit, if the armour is is the cpc then go with Baker1988.

 

[Steve T]

The armour is not the Cpc, there is a cpc inside the cable. I will use 1.5mm cable as the fly lead, and I might go for the wiska 407 instead to give myself more space. It has also got similar earth bars available.

 

[westward10]

I got the copper equivalent to about 2.0mm in terms of conductivity.