Swa Banjo?

[Michael Bloomfield]

Hello everyone, having a debate with colleague, concerning SWA connected into metal CU. Can anyone advise the exact reason for the banjo, brass washer with cpc tag, is it compulsory rather than it just looks nice.
Any thoughts sound reasons would be nice also is it a requirement under the regs?

 

[Michaelwgroves]

I use gn8 tables or manufacturer data for actual CSA of the steel armour but like has been said the copper-steel ratio is around 8.5 difference in conductivity so as an example if a steel conductor was used as a protective bonding conductor then the CSA of the steel would need to be 85mm to be the equivalent of the required 10mm copper

This is also covered in Guidance Note 8 Earthing & Bonding 5.2.1 pg 60.
I think it's also covered generally in Guidance Note 1, selection and Erection. I think the statement used is generally you should not use SWA for main protective bonding, but I can't recall which section this was.

 

[bonjovi]

is this question real really , as most on hear know the armourings are used as protection for the cable which is usually used when its installed in areas likely to get mechanically damaged ,ie buried ,spade digging ,and secondly a lot of sparks still use this as a cpc to keep the cost down and not include a extra core as a earth , either way the armourings need to be earthed, this is done via a gland , banjo nut and bolt for a solid earth and flylead . its beggers belief to think there are guys out there doing work not knowing such a thing

 

[Pete999]

is this question real really , as most on hear know the armourings are used as protection for the cable which is usually used when its installed in areas likely to get mechanically damaged ,ie buried ,spade digging ,and secondly a lot of sparks still use this as a cpc to keep the cost down and not include a extra core as a earth , either way the armourings need to be earthed, this is done via a gland , banjo nut and bolt for a solid earth and flylead . its beggers belief to think there are guys out there doing work not knowing such a thing

 

[telectrix]

i always use a banjo:

OK it's a UKelele. thank God it's no longer an EUelele.

 

[Ib≤In≤Iz]

I mostly use piranha nuts now, much better and neater than a banjo. Brass for me too and always a fly lead to the earth bar.

 

[SJD]

It has the banjo fitted so it must be fine!!!
What on earth did they manage to do to that gland to rip off the end of the clamp nut?

I finally started the remedial work on these glands (4 in total), the original installer had bought size 20 glands when the cable needed size 25. The badly damaged one, it looks like they'd had a go at trying to get the armour inside but given up after damaging the gland. The other three, they'd just snipped it all off.

 

[soms]

Without having my books to hand, having not (yet) been taught this and calling on the years of valuable experience available here, how does one select the CSA of the fly-lead?
Should it follow the usual rules for sizing CPCs - either be the same CSA as the live conductors or be selected by calculation using the adiabatic equation?
Surely unless it is correctly sized it may also prove unreliable under fault conditions?

 

[Ian1981]

Without having my books to hand, having not (yet) been taught this and calling on the years of valuable experience available here, how does one select the CSA of the fly-lead?
Should it follow the usual rules for sizing CPCs - either be the same CSA as the live conductors or be selected by calculation using the adiabatic equation?
Surely unless it is correctly sized it may also prove unreliable under fault conditions?

If you are utilising the armour as the circuit cpc then yes I would use the Adiabatic or the tables and size the fly lead accordingly.
If I am just earthing it and using a core within the cable as my cpc then I will use a minimum of 2.5mm for the fly lead , if mechanical protection is not necessary.
Depending if we are dealing with larger swa cables where the fault current is likely to be higher and more severe then I would install a larger fly lead put probably nothing larger than 10mm

 

[Tes369]

Without having my books to hand, having not (yet) been taught this and calling on the years of valuable experience available here, how does one select the CSA of the fly-lead?
Should it follow the usual rules for sizing CPCs - either be the same CSA as the live conductors or be selected by calculation using the adiabatic equation?
Surely unless it is correctly sized it may also prove unreliable under fault conditions?

Generally you don't somebody on more money than you does who drives a nicer car than you.


On a glaxco chemical plant I was on recently all the earthing flies were 6mm.

There was a big debate going on because EX SWA glands the sheath were left off because not required. They liked it in the end as no armour showing anyway.

Lots of earthing going on if the pipes resistance was greater than 10 ohms across the flange then flies were put between the flanges on pipes.

The Electrical engineer in the office had the final say on what went down with his brand new Audi in the car park to prove it.

 

[Pete E]

I use these when terminating into a plastic box. Great way to maintain earth continuity

View attachment 41521

Just curious what they are called?

 

[123]

Just curious what they are called?

It's a Wiska EMC Earth Clamp

 

[Pete E]

Thanks, much appreciated!

 

[timbobelfast]

Generally you don't somebody on more money than you does who drives a nicer car than you.


On a glaxco chemical plant I was on recently all the earthing flies were 6mm.

There was a big debate going on because EX SWA glands the sheath were left off because not required. They liked it in the end as no armour showing anyway.

Lots of earthing going on if the pipes resistance was greater than 10 ohms across the flange then flies were put between the flanges on pipes.

The Electrical engineer in the office had the final say on what went down with his brand new Audi in the car park to prove it.

6mm is the norm for all Petro-chemical sites, hope they used copper tube lugs rather than the crappy yellow lugs the fail in no time!

 

[Tes369]

6mm is the norm for all Petro-chemical sites, hope they used copper tube lugs rather than the crappy yellow lugs the fail in no time!

There was some really nice Pyro work on that job and the new EX rated emergency stop buttons were a fraction of the size of the original equipment ex emergency buttons. And I bet they last a fraction as long as well.

All the old gear had "Made In Great Britain" on it

 

[telectrix]

i've got made in britain stamped across my navel. ain't done me any favours.