UK Steel Tape Armour and Reduced Neutrals

[GreyBeard]

Hi, someone has ordered Steel Tape Armoured cable instead of SWA. Can I use this armour as a CPC the same as SWA or not and if so is there a table so that I can check the figures.

Secondly, correct me if I am wrong but 3ph with a reduced neutral should only be used on a balanced load ie a single pump/motor etc - it is not meant to be used to feed a panel supplying single phase loads?

 

[Dustydazzler]

steel tape armoured cable - Bing

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[Dustydazzler]

Looks very European / American that type of foil wrapped cable ?

 

[Rockingit]

It'll be down to the Manufacturer as to what specification the armour is designed for and whether or not it has a BASEC standard. I'd have thought the biggest pain would be getting the correct glands for it.

As for the reduced size Neutral see 524. The dependant factors are on line conductor size / type and not useage.

 

[Dustydazzler]

After a bit of research it does look like Americans / Canadian sparks are allowed to use the steel Tape as the ground on some of the cables but not on the all. It has to be specifically rated so you can use the steel tape wrap for the grouding.

So as above I would want to check with the cable makers insctructions and specification manual ( very carefully ) before committing to this type of cable in a UK install

 

[westward10]

Steel tape cables were not unusual in this country, normally covered with tar soaked hessian. Where have they ordered it from as I have not seen it in modern use?

 

[nicebutdim]

Steel tape cables were not unusual in this country, normally covered with tar soaked hessian. Where have they ordered it from as I have not seen it in modern use?

1954

 

[Dustydazzler]

Its this ting innit

Can't say I have seen this used in modern day installs here in the Uk

 

[DPG]

Think I'd be sending it back to be honest. It's just going to cause grief.

 

[pc1966]

I would be concerned that the resistance / heating is much higher as it is spiralled around. Also if the usual glands would properly grip it to connect.

Maybe they have considered that already, but it is not something i have seen on any modern power cable, just sometimes the armour on fibre networking stuff where it is largely mechanical protection.

 

[ipf]

As westwood says, hessian/tar jobs.
This is a house supply, originally 3 phase, I think from the 1930's. The hessian has rotted but the steel wrap can be seen where the cable comes through the wall. You would think that the steel would be rusted and knackered but it is solid as a rock. The head had to be sorted out by ENWL so they had to cut some of the steel spiral back...with amazing difficulty, to re do the cable head and re earth with a constant force spring.
These days, I can't imagine it being anything like as solid.

 

[GreyBeard]

Its this ting innit

Can't say I have seen this used in modern day installs here in the Uk

Thats the old paper insulated lead sheath type, but this is PVC type outer sheath 3 x 120mm Phases with 70mm Neutral no earth (hence my question)

 

[GreyBeard]

I would be concerned that the resistance / heating is much higher as it is spiralled around. Also if the usual glands would properly grip it to connect.

Maybe they have considered that already, but it is not something i have seen on any modern power cable, just sometimes the armour on fibre networking stuff where it is largely mechanical protection.

Agreed, forgot about the ambient temperature, I am working in Sinai on a base to UK regs where the temp is usually 30C to 40C, so overheating would be a problem too. Its 3 x 120mm phase and 70mm neutral with no earth, but the tape looks so thin and its been supplied to be used on the new barrack blocks - these have single phase loads which are by no means balanced - yes if everything is on at the same time its ok but not everyone puts the kettle or AC on at the same time.

 

[GreyBeard]

I would be concerned that the resistance / heating is much higher as it is spiralled around. Also if the usual glands would properly grip it to connect.

Maybe they have considered that already, but it is not something i have seen on any modern power cable, just sometimes the armour on fibre networking stuff where it is largely mechanical protection.

I do not think so, rather someone has seen that this cable is cheaper than what was ordered and thought to save some money. Yes Steel Tape needs its own set of glands and terminating is a pain (cut fingers etc). I have said that if they insist on using it then it has to be derated down to the same size as the neutral and an external earth ran with it.