SWA to T&E. Moving a plastic junction box. Gland and banjo question

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I have a few 3 core SWAs supplying sheds and garage coming into a plastic junction box inside the house (in a mini plant cupboard) where they connect to individual T&Es using chocolate block. The T&Es then go onward into separate circuits in the CU on the other side of the house.

The SWAs are terminated using CW type glands. There are no banjos inside or outside this junction box, so I think the armours are floating. Supply type is TT.

The T&Es are poked through holes in the top of the junction box, no gland.

This work was done by an electrician 4 years ago.

I want to replace the junction box with a bigger one and move it to an adjacent wall myself. There is enough slack in the cables to move them. Then I want to get an electrician to connect and test a couple of extra SWA and T&E cables.

I don't want to make any fundamental errors in replacing the box, so questions as follows.

  1. Is the box move itself notifiable?
  2. Is a plastic box still ok? Or must it now be metal?
  3. The box is inside the house, are CW glands necessary, or would BW glands have been ok?
  4. Must each SWA armour be connected via a banjo to the earth core of it's respective SWA in the junction box?
  5. Must the T&E be glanded into the box? If so, I have some of these, are they suitable? https://www.toolstation.com/ip68-gland-locknut-kit/p80473
  6. Anything I've missed?

Cheers!
 
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I have a few 3 core SWAs supplying sheds and garage coming into a plastic junction box inside the house (in a mini plant cupboard) where they connect to individual T&Es using chocolate block. The T&Es then go onward into separate circuits in the CU on the other side of the house.

The SWAs are terminated using CW type glands. There are no banjos inside or outside this junction box, so I think the armours are floating. Supply type is TT.

The T&Es are poked through holes in the top of the junction box, no gland.

This work was done by an electrician 4 years ago.

I want to replace the junction box with a bigger one and move it to an adjacent wall myself. There is enough slack in the cables to move them. Then I want to get an electrician to connect and test a couple of extra SWA and T&E cables.

I don't want to make any fundamental errors in replacing the box, so questions as follows.

  1. Is the box move itself notifiable?
  2. Is a plastic box still ok? Or must it now be metal?
  3. The box is inside the house, are CW glands necessary, or would BW glands have been ok?
  4. Must each SWA armour be connected via a banjo to the earth core of it's respective SWA in the junction box?
  5. Must the T&E be glanded into the box? If so, I have some of these, are they suitable? https://www.toolstation.com/ip68-gland-locknut-kit/p80473
  6. Anything I've missed?

Cheers!

Don't think the box move is notifiable.

Plastic jb is fine.

I personally prefer CW glands, but BW are adequate here.

Armour should be connected to earth at the jb end only, use piranha nuts rather than banjos.

T and E doesn't need glanding, but it must be restrained. Personally, I would gland it, you can get stuffing glands with T and E inserts.

Get a jb with a bit of DIN rail and proper terminals, and you will end up with a nicer job, allow room for your planned extra circuits.

Your previous electrician was no electrician, don't use them again.
 
Armour should be connected to earth at the jb end only, use piranha nuts rather than banjos.

Can I loop the earth from one armour to the next with the last loop connecting to one of the T&E earths? Or should I connect each armour into it's respective core?
Any reason not to solder the earth cables to the banjo or piranha nut? I've just tried it and is fairly straightforward with a decent power iron. I have 10mm earth cable.

I don't have any piranha nuts and want to do the work tomorrow, but will put it off if using the banjos is a bad idea.

Yes I've got din rail, terminals and slotted trunking for the slack.

Thanks for the reply.
 
Mini plant?

upload_2020-1-3_22-59-40.png


Or

upload_2020-1-3_23-0-54.png
 
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lol. Ok ok a broom cupboard with a boiler in it and lots of plumbing!
 
Can I loop the earth from one armour to the next with the last loop connecting to one of the T&E earths? Or should I connect each armour into it's respective core?
Any reason not to solder the earth cables to the banjo or piranha nut? I've just tried it and is fairly straightforward with a decent power iron. I have 10mm earth cable.

I don't have any piranha nuts and want to do the work tomorrow, but will put it off if using the banjos is a bad idea.

Yes I've got din rail, terminals and slotted trunking for the slack.

Thanks for the reply.

Banjos aren't a bad idea, there are gazillions of them in use, but the electrical connection between gland body and banjo is made by compressing the banjo between jb and gland nut, and there are some that believe they come loose over time.

Why solder rather than nut bolt and ring crimp? 10mm earth is oversized but that is not a problem, soldering is no problem either.

No reason to connect the armour to its particular earth core, just lump it all together in the jb as it's all in the house, DIN rail earth terminals would be the thing to use, connect all earth and armours into a block of them and the DIN rail connects at all together.
 
For internal use banjos should be fine as long as you lock them off good and tight- not a lot of corrosion problems in your plant room :) . Yeah the tag washers are a bit of a potential fail path especially into a plastic box- last time I did some I used extra gland nuts to lock the tag washer to the gland & then another nut to secure the gland to the box.
EDIT That of course left the tag outside the box- you can do the same trick in reverse though, nut to secure gland to box then another nut to secure tag to 1st nut. Metal to metal means you can gorilla it without deforming the plastic.
 
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Banjos aren't a bad idea, there are gazillions of them in use, but the electrical connection between gland body and banjo is made by compressing the banjo between jb and gland nut, and there are some that believe they come loose over time.
Whilst that is true, much the same is also true of the electrical connection between the SWA armour and the gland body - which is more of a 'plumbing' connection than familiar electrical ones! I've certainly seen that particular 'joint' come pretty loose over time.

Kind Regards, John
 
Here's the old box.

nsmail-1-1.jpg



Here's my new box mounted on the other wall with one of the 16mm2 cables moved across to try the layout. I'm going to have to redo the gland because the armour has come away.

What size should the earth tag cable be? Is 2.5mm2 ok? These circuits all have RCD protection upstream, so any current in the earth cable will be for a short time presumably. I've soldered 10mm2 cable here which was a bit of a pain to bend, so I'll know for the next box(!).


nsmail-2-1.jpg




I've also tried to gland another 16mm2 cable with these BW type.

https://www.cef.co.uk/catalogue/products/23128-25-m25-bw-cable-gland-pack-pack-of-2

and failed completely. I couldn't get the armour to clamp properly as I tightened the nut. Some ends of armour came out of the nut. In contrast I've had no issues with the CW type which has a ring, not just a nut. I'll try again tomorrow.
 
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Others more knowleagable than me may be disagree but I'd say the earth on the armours should be the same size or greater than the largest conductor (so if they're all 4mm then a 4mm earth would do, if one of them is 6mm then use 6mm earth). Dunno why you're bending it- if soldering just line the tags up and fire it on. Have to say your existing box does look rather shoddy- its good that there's spare on the SWA but the 'electrician' could have made it neater
 
Faced with terminating SWA to a plastic enclosure I used a die-cast box for the transition and kept the inner sheath intact as far as the terminals in the enclosure.

 
Progress so far. I did test the spacing with a piece of card before drilling the box, and I can just get the spanner on and rotate the nut. But yes it is tight, and I hadn't allowed for the thickness of 2 dust covers next to each other.

I made a template in Draw, printed it out, pritt-stuck it to the box and then used a step drill to make the holes. The paper and glue then washed off under the hot tap. Accurate and worked a treat, and the next box will be much quicker.

Once I'd improved my accuracy with cutting the armour strands to the same length, then everything went much smoother!

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Other questions. At the far end the armour is not going to be connected to earth, so what is the reason for using a brass gland in the plastic box? Just mechanical support? Would a Nylon gland be ok? Does the answer change depending on whether the box is indoors or outdoor? Cheers.
 
Other questions. At the far end the armour is not going to be connected to earth, so what is the reason for using a brass gland in the plastic box? Just mechanical support? Would a Nylon gland be ok? Does the answer change depending on whether the box is indoors or outdoor? Cheers.

A CW gland is the correct gland for terminating SWA outside. Yes, you could use a nylon stuffing gland, but that would be nasty. Just use the correct gland and don't connect the gland body to earth.
 

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