New outbuilding question.

[davesparks]

Stripping it down and squeezing it into a buried 20mm conduit sounds like a bad idea to me, you'll end up needing to RCD protect the distribution circuit.
How would you be intending to gland the SWA at the point it joins to the PVC conduit?

As for the joint i'd use through crimps or din rail terminals if it has to be in an enclosure on the wall or probably a torpedo joint if it's hidden away.

As far as terminals for a load like that go through crimps are obviously available for all sizes of cable. Regular DIN rail terminals are available up to 95mm and DIN mounted bolted terminals go up to very high current.

 

[OutOfTheGame]

Stripping it down and squeezing it into a buried 20mm conduit sounds like a bad idea to me, you'll end up needing to RCD protect the distribution circuit.
How would you be intending to gland the SWA at the point it joins to the PVC conduit?

As for the joint i'd use through crimps or din rail terminals if it has to be in an enclosure on the wall or probably a torpedo joint if it's hidden away.

As far as terminals for a load like that go through crimps are obviously available for all sizes of cable. Regular DIN rail terminals are available up to 95mm and DIN mounted bolted terminals go up to very high current.

Hi, thanks for replying.

The existing conduit is a dissused one that basically comes down the inside of an internal wall and pops out in a wiska box mounted on the outside of the building, I would terminate it in there.
That drop is about 2M, the sections before and after that drop would remain in SWA the idea was to use 3 core SWA internally so that I could earth the armour of the existing external 2 core SWA.

To get rid of the outer sheath I was going to use an adaptable box with a SWA gland one side and a stuffing gland holding the inner circular section in the other side, before finally going to the individual cores for that drop.

The cable will indeed be RCD protected by a 100ma RCD protecting the cable itself and then 30ma RCDs in the outbuilding.
The intention was either to terminate in there or second choice would be a normal torpedo joint and going down the cavity therefore remaining 100% SWA.

 

[nicebutdim]

I don't see three 16mm cores going through this 20mm conduit. Yes it has been proven they'll fit into a straight length and you can ensure they go in nicely, but that conduit goes through a wall and that means one of two things: 1. it has been bent and those bends will flatten it slightly. 2. Slip bends are fitted and they'll bust off.

By all means give it a go if you think it's worth trying, but don't pin your hopes on it.

 

[brianmoooore]

The cable will indeed be RCD protected by a 100ma RCD protecting the cable itself and then 30ma RCDs in the outbuilding.

It's only in limited circumstances that you will get discrimination between the two RCDs, and if any part of your supply cable, where it is not SWA, is buried within 50mm of the surface of a wall, the first RCD is required to be 30mA, not 100mA

 

[OutOfTheGame]

I don't see three 16mm cores going through this 20mm conduit. Yes it has been proven they'll fit into a straight length and you can ensure they go in nicely, but that conduit goes through a wall and that means one of two things: 1. it has been bent and those bends will flatten it slightly. 2. Slip bends are fitted and they'll bust off.

By all means give it a go if you think it's worth trying, but don't pin your hopes on it.

That may well make the decision for me but I put the conduit there is straight down the wall with one 90° bend about one foot from the end. I guess once the boards are up and it won't go I could just go cavity route?

I was just trying to discuss to see if there were any better ideas out there among all you experienced people as well confirm the options I had come up with were making the best of a bad job.

If I do manage to get the cores down does anyone know how much it at all ill need to derate the cable? Would I just consider the whole cable to be reference method A or B? It's in a standard cavity brick wall with dry-lined dot n dab over the top.

 

[davesparks]

To get rid of the outer sheath I was going to use an adaptable box with a SWA gland one side and a stuffing gland holding the inner circular section in the other side, before finally going to the individual cores for that drop.

Once the outer sheath is removed from the SWA it needs to be enclosed in conduit, the bedding layer is not compliant as an outer sheath and cannot be left unenclosed.

The cable will indeed be RCD protected by a 100ma RCD protecting the cable itself and then 30ma RCDs in the outbuilding.

That does not comply for protecting a cable buried in the wall, with the armour removed, and conductors protected by PVC conduit, it will have to be protected by 30mA RCD.

The intention was either to terminate in there or second choice would be a normal torpedo joint and going down the cavity therefore remaining 100% SWA.

 

[nicebutdim]

I can't help wondering about earthing arrangements and how important aesthetics really are when attempting to make the best of a less than ideal situation.