Armoured cable & T&E

[Igor Taranenko]

Hi All,

I have a job to install 6mm supply to a small outbuilding. Ideally i would run SWA all the way from Meter box(im taking it from Henley block) to the outbuilding, but not in this case. Cable will have to go through the kitchen area. So im thinking to have 6mm t&e in trunking, it's only about 4 meters. But my concern is that this cable has 2.50mm earth conductor as opposed to 6mm on swa. Another option is to run 3 singles in the trunking, all 6mm. Is that good practice?
Any help would be great

 

[Strima]

What do your design calculations tell you?

Also your splitting the tails, what protection are you going to use?

 

[Dustydazzler]

Either way you can’t take a 6mm csa cable straight off a standard 100a cut-out via Henley blocks.
the entire submain will require suitable overload protection and rcd protection.
you will need to install some sort of single way consumer unit to provide both.

 

[Igor Taranenko]

What do your design calculations tell you?

Also your splitting the tails, what protection are you going to use?

Current design is fairly small not more then 20A based on maximum demand.
Yes, i have to split tails, its TNCS system there is a spare terminal for main earth conductor at the service head so i can use when connecting swa at the meter box. Protection: 40a double pole rcbo inside the meter box in the small 2 module consumer unit
[automerge]1596830288[/automerge]

Either way you can’t take a 6mm csa cable straight off a standard 100a cut-out via Henley blocks.
the entire submain will require suitable overload protection and rcd protection.
you will need to install some sort of single way consumer unit to provide both.

Yes, im fitting small CU with 40a rcbo inside meter box, just didn't mention that

 

[pc1966]

So im thinking to have 6mm t&e in trunking, it's only about 4 meters.

Can't you get the SWA through?

Generally less joints the better.

 

[Igor Taranenko]

Can't you get the SWA through?

Generally less joints the better.

It needs to go through inside for about 4m. I found solution. I cut section of swa, removed outer sheath and steel armour and fit remaining 3 cores with inner sheath in trunking. So I've achieved continuous 6mm earth connection.

 

[davesparks]

It needs to go through inside for about 4m. I found solution. I cut section of swa, removed outer sheath and steel armour and fit remaining 3 cores with inner sheath in trunking. So I've achieved continuous 6mm earth connection.

As long as it is fully enclosed in the trunking it is OK. That inner sheath is not a sheath, it is bedding, so it must be installed with the same protection as you would for single insulated cables.

How did you gland and earth the SWA cable for this arrangement?

 

[Igor Taranenko]

As long as it is fully enclosed in the trunking it is OK. That inner sheath is not a sheath, it is bedding, so it must be installed with the same protection as you would for single insulated cables.

How did you gland and earth the SWA cable for this arrangement?

Its fully inclosed in 25 x 25 trunking. Ive used outdoor swa glands and adaptable box, as well as fly lead to connect steel armour and earth