Flylead to SWA without a banjo.

[davesparks]

I've been working my way through some EICR remedials in a theatre and one of them is to sort out a slightly high Zs on a submain.

Thankfully whoever installed it put the banjo on the gland and even put a bolt through it, they just didn't add a flylead, so its going to be relatively easy to fix that element of it. But it has got me wondering what could be done, or what other people might do if there wasn't already a banjo on the gland.

Obviously with most such situations you'd probably disconnect the conductors, remove the locknut and replace it with an earthing nut. But in this instance the cable is 400mm 4 core (I assume whoever designed this had never actually been on site and had to install a cable of that size or else they'd have split it into parallel cables, or they just hated the poor guys who had to install it) so there's not much chance of that happening.

I think if there hadn't been a banjo I would probably would have gone with something like a big earth clamp like you'd use for attaching lightning conductors to pipework and attached it to the main body of the gland. Something like this:

And this is the offending gland:

 

[freddo]

I think I would have done some paint removal If I was relying on an earth connection to the enclosure. My arms are aching just looking at that photo. Single core AWAs FTW!

 

[davesparks]

I think I would have done some paint removal If I was relying on an earth connection to the enclosure. My arms are aching just looking at that photo. Single core AWAs FTW!

I'd have had a word with the designer and explained to them why they were going to re-design this as a set of 3 parallel cables.

Also I think the box it is glanded into wasnt part of the original plan, the switchboard it is on top of has the usual bare aluminium gland plate and I suspect that the spreader box was added on site as there's no where near enough room to take that cable up and have it come in vertically.

 

[littlespark]

Can you strip some of the sheath off further back and use one of this constant tension springs that you would find in an underground joint kit?

 

[R-fur]

What is the bolt for below the gland? Could they have fitted the banjo outside the box?

 

[davesparks]

What is the bolt for below the gland? Could they have fitted the banjo outside the box?

Yes, as I said in the OP there is a banjo on this one, my question is what would you do if there wasn't a banjo on there.

 

[Rockingit]

Yes, as I said in the OP there is a banjo on this one, my question is what would you do if there wasn't a banjo on there.

Then I think inventiveness is called for! It could be argued that stripping outer sheath to use a clamp of some sort degrades the integrity of the cable so I'd call that a last resort. What, maybe, could be made to work would be to loosen the gland such that you could slide behind it two banjo's cut in half (not the blade, obviously!) that when in place clamp against each other to form a solid bond again.

There again, with a 400mm sized gland you could probably very carefully tap a 4mm brass bolt into the side of it and make a DIY piranha.

 

[westward10]

I have cut some banjos not in half just to spring it around on some 185.0 but it isn't as easy as it sounds. We had to loosen off the gland itself and use that to tighten as using the lock nut just split the banjo out. There was a lot of cursing and cut fingers but you would never know they had been cut.

 

[Rockingit]

I have cut some banjos not in half just to spring it around on some 185.0 but it isn't as easy as it sounds. We had to loosen off the gland itself and use that to tighten as using the lock nut just split the banjo out. There was a lot of cursing and cut fingers but you would never know they had been cut.

That was my first thought but I figured you'd never get a banjo that size to deform and reform without totally knackering it in the process!

 

[westward10]

That was my first thought but I figured you'd never get a banjo that size to deform and reform without totally knackering it in the process!

No it doesn't do it much good and once under the hex lock nut it was fine. Not something I would recommend it isn't easy.

 

[James]

I like @littlespark idea, use a torpedo joint, cut the outer cover off a couple of feet from the board
joint an earth cable on using the constant force spring
place the torpedo joint cover over and fill with resin.
good solid earth joint without too much physical workout.

 

[Baddegg]

Obviously out of my realm but I was thinking along @westward10 idea, loosen the lock nut and cut a section of the banjo out enough to just spring it over and then tighten lock but back down….

 

[freddo]

There again, with a 400mm sized gland you could probably very carefully tap a 4mm brass bolt into the side of it and make a DIY piranha.

M4 isn't much of a connection point! Imagine drilling in too far and hitting one of the phase cores, while the power is on...

 

[James]

M4 isn't much of a connection point! Imagine drilling in too far and hitting one of the phase cores, while the power is on...

we have all drilled into something live once HAVENT WE?
it goes with a bang and costs you a new drill bit and a pair of underpants!!!

 

[freddo]

we have all drilled into something live once HAVENT WE?
it goes with a bang and costs you a new drill bit and a pair of underpants!!!

I've never drilled into a 400mm cable though! (Not yet anyway) I'm assuming the cable is sized for high current handling not a really long 10amp lighting circuit!

 

[davesparks]

I've never drilled into a 400mm cable though! (Not yet anyway) I'm assuming the cable is sized for high current handling not a really long 10amp lighting circuit!

Oh yeah, it's a 400A TPN submain of a fair length.

Technically you could say it's a lighting circuit though as it does feed the stage lighting dimmers!

 

[davesparks]

I have cut some banjos not in half just to spring it around on some 185.0 but it isn't as easy as it sounds. We had to loosen off the gland itself and use that to tighten as using the lock nut just split the banjo out. There was a lot of cursing and cut fingers but you would never know they had been cut.

Interesting idea, I'll remeber that one.

It possibly wouldn't have worked on this particular one as what you can't really see from the picture is that the gland itself is behind a large trunking taking the outgoing circuits from the DB it feeds.

 

[freddo]

Oh yeah, it's a 400A TPN submain

400A bangs are quite impressive. One was enough though.