I need to join two lengths of 4mm armoured cable - above ground - in fact I'll need three junction boxes in total.
I know I can get this sort of thing -
I should add that this cable is to run along a garden border about a foot off the ground.
Try:
Thanks for that. They look as if they would fit the bill.
If you are using the steel sheath as an earth with plastic adaptable boxes you will have to connect the glands together in each box. However if using a SWA with three conductors one being used as an earth then that is not necessary and you can probably be able to use cheaper stuffing glands with the adaptable boxes.
Richard
Good point, and thank you. I haven't really checked the SWA yet, but obviously I will do before I order anything. All I know at the moment is that it's 4mm.
Wiska have optional earth bar kits available for that.
I thought the armour always had to be earthed, whether it was also being used as the circuit protective conductor?
Owain
That is my understanding.
It must be earthed - even if it only at one end
Yes.
No, the armour must always be earthed - that is kind of the point of SWA
- if you do manage to damage the cable, its difficult to do in a big way without shorting the armour to the core.
What you really want is the circuit protective device(s) to notice this event, and turn off the power. Not have a live core make the armour and any attached metalwork live instead!
Yup, I quite like those...
For a "straight through" join, the metal conduit boxes make gland to gland earth continuity a bit easier though, and are very robust.
(he will need three sets of glands as well - probably 20s for 2 core SWA, or 20 for 3 core).
3 core 4mm uses a 20s.
Yup could be - I have seen conflicting info on that. Our table :
We probably should update our table.
And end up as accurate as the cleat size recommendations that manufacturers use?
The only use for black insulation tape is to pack out the SWA when the cleats are too big.
Wouldn't they be difficult to seal completely? And,in my experience, galvanised fittings always rust around the threads.
I know that they wouldn't be quite as robust, but wouldn't strong plastic boxes be better overall?
Offcuts of sheath would be less likely to creep under pressure, and save buying insulation tape.
Owain
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