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?

 

[Octopus]

I would venture to suggest its not required ............ but you could use a piranha nut if you wanted.

 

[Pete999]

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?

The Banjo is there to provide a connection from the gland to the earth bar via a fly lead, Jeez what a question.

 

[Michael Bloomfield]

Pete 999 why is the earth connection not connected via the earth bar which is connected to the metal CU, also I would prefer simple sensible answers if it requires a "jeez" then dont bother answering. we all learnt over time I find it frustrating when someone just knew it all straight away.thanks

 

[Pete999]

Pete 999 why is the earth connection not connected via the earth bar which is connected to the metal CU, also I would prefer simple sensible answers if it requires a "jeez" then dont bother answering. we all learnt over time I find it frustrating when someone just knew it all straight away.thanks

It's a basic installation procedure, surely they taught you this during your training.

 

[Pete999]

Pete 999 why is the earth connection not connected via the earth bar which is connected to the metal CU, also I would prefer simple sensible answers if it requires a "jeez" then dont bother answering. we all learnt over time I find it frustrating when someone just knew it all straight away.thanks

It's something you should have known before attemptigany work with SWA cables, sorry you found my post not to your liking, but it really is a basic procedure.

 

[Octopus]

Pete999 - its a metal CU ................................

 

[Pete999]

Pete999 - its a metal CU ................................

So? with the stabdard of practical training these days not many people are taught to clean the SWA and conduit entry points any more, so would you not use a Banjo or Piranha nut when terminating SWAs to a Metal enclosure, and not use a fly lead from the SWA termination point to the earth bar? if the case is that SWAs are just terminated into the enclosure, then why do SWA gland manufacturers include a Banjo in their kits. In saying that I can see where the confusion may lie, with regards to a metal and a non metalic enclosure. May be the fly lead is not the B all and end all but at least use the Banjo to form a decent conectionto the metalic enclosure.
I apreciatemy initial reply may have been a bit harsh, but maybe this is not his fault, the fault probably lies with the shoddy training, I'm not sure which. OP I apologise if I erked you off.

 

[Pete999]

Pete 999 why is the earth connection not connected via the earth bar which is connected to the metal CU, also I would prefer simple sensible answers if it requires a "jeez" then dont bother answering. we all learnt over time I find it frustrating when someone just knew it all straight away.thanks

I don't profess to know it all Micheal, never have and never will.

 

[Richard Burns]

If an SWA cable is simply glanded into a metal box then it is likely that the electrical contact between the gland and box is not reliable, particularly where the box is painted, even cleaning the area may not be enough. Therefore the standard approach is to use a banjo and flying lead to ensure the continuity of the earthing of the armour.
An easier method is to use a piranha nut, these do have teeth on one side to score the surface of a metal box, but this may still not be enough so the fly lead is still connected.
All this is to ensure the cables armour is reliably connected to earth with a joint of suitable mechanical and electrical strength.

 

[cliffed]

What about the grommets,I know many who don’t.

 

[Spoon]

Pete 999 why is the earth connection not connected via the earth bar which is connected to the metal CU, also I would prefer simple sensible answers if it requires a "jeez" then dont bother answering. we all learnt over time I find it frustrating when someone just knew it all straight away.thanks

The cores of the SWA go thought the gland. The armour of the cable connector to the gland. Look up SWA glands and how to wire to them, you will understand better. You have to earth the gland properly. That's why you use the banjo or brass washer with cpc tag.

Bugger... Richard beat me to it.

 

[SJD]

How about a nice example of how NOT to terminate SWA (and this is a plastic enclosure) from an EICR I did last week

 

[Octopus]

So Pete999 - a banjo - fixed to the CU with a nut and bolt and a fly lead?

 

[Richard Burns]

How about a nice example of how NOT to terminate SWA (and this is a plastic enclosure) from an EICR I did last week

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?

 

[Michael Bloomfield]

Many thanks for your reply Richard Burns which makes lots of sense, behind the use of a banjo.
Although i wish the locking nuts provided were just a fraction thicker to get a good purchase on when tightening but thats obviously cut backs, i quite often use piranha and flying earth lead, my companion debated that if earth continuity was present with as he said measured to 0.00 ohms on meter is that not sufficient continuity, i gracefully conceded the debate.

 

[Pete999]

So Pete999 - a banjo - fixed to the CU with a nut and bolt and a fly lead?

Could do it that way I prefer a Piranha nut a far better and neater approach.

 

[Pete999]

So Pete999 - a banjo - fixed to the CU with a nut and bolt and a fly lead?

Could do it that way I prefer a Piranha nut a far better and neater appr

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?

They cut the Armour out of the equation Richard, because they didn't know how to do it properly, you can see from the pics that the Armour was/is /wouldn't reach thecorrect position to form a proper termination.

 

[Spoon]

my companion debated that if earth continuity was present with as he said measured to 0.00 ohms on meter is that not sufficient continuity, i gracefully conceded the debate.

I don't quite understand this bit. What did your companion actually measure between to get this reading? How accurate is his meter?

 

[Richard Burns]

It is the reliability of the connection that is the issue, with a very short distance from gland to metal it is easy to get a 0.00Ω measurement but the contact area could be only 0.5mm² and this may not withstand an earth fault current, melt and and so leave the armour disconnected at the very time it is needing to be earthed.