Joining SWA With Lead Internal Sheath?

Retroelectric · Jun 14, 2022

Hi all.
Been asked to join a couple of 25mm 4 core Swa's underground so am using a couple of torpedo's.
This is probably a basic question but one of the cables has a inner lead sheath so you have.

Insulation
Armour
Insulation
Lead Sheath
Insulation
Double Insulated Cores

Whats the deal with the lead and how or do you need to earth it as its stuck between 2 layers of insulation?

[ElectriciansForums.net] Joining SWA With Lead Internal Sheath?

James · Jun 14, 2022

Wow, never seen that before.

Retroelectric · Jun 14, 2022

Me neither.
Not sure what you do with the inner lead?

Yozza19 · Jun 14, 2022

That lead has been used for a screen cable maybe fp400 may be the best option if it is available in correct size

Petej999 · Jun 15, 2022

Retroelectric said:
Hi all.
Been asked to join a couple of 25mm 4 core Swa's underground so am using a couple of torpedo's.
This is probably a basic question but one of the cables has a inner lead sheath so you have.

Insulation
Armoring
Insulation
Lead Sheath
Insulation
Double Insulated Cores

Whats the deal with the lead and how or do you need to earth it as its stuck between 2 layers of insulation?

What you need is the services of a pro cable jointer, not the sort of task for an unexperienced guy

westward10 · Jun 15, 2022

Seems to be an additional layer of protection.

EEMUA 133 Lead covered armoured Power Cables to BS 5467, 1900/3300V - BS5467 Cables

These power and control cables are well adapted to underground use in industrial applications, in moist areas, where hydrocarbon and mechanical protections are needed and are protected against solvent penetration and corrosive attacks.

www.caledonian-cables.co.uk

timhoward · Jun 15, 2022

I saw one of these as a link cable between two very old fire alarms in different buildings. Luckily my job was simply to remove it.

pc1966 · Jun 15, 2022

Retroelectric said:
Not sure what you do with the inner lead?

I expect it should be earthed, but probably a job for a constant-force spring and some braiding to add to the armour link in the joint.

Maybe worth contacting one of the joint manufacturers like Birkett Cable joints for advice:

Birkett Electric | Manufacturers of Underground Cable Joints

Underground resin cable jointing kits, mechanical connectors and accessories

www.birkett-electric.com

Retroelectric · Jun 15, 2022

Thanks, I have called Birkett, they do nothing different to accommodate the lead.
He said that cable is used in oil refinaries etc and the lead is nothing to do with the earthing, just a protection for the inner cores from corrosive chemicals.

pc1966 · Jun 15, 2022

Retroelectric said:
He said that cable is used in oil refineries etc and the lead is nothing to do with the earthing, just a protection for the inner cores from corrosive chemicals.

It just seems wrong to be left floating! More so if hydrocarbons are involved...