UK Acceptable ways to terminate SWA - standard practice question

[Fall-Apart-Dave]

Hello folks

Inhave my 18th Edition and Part P l, but I dont trade as a sparks.

I have a question about best practice for terminating SWA.

I am currently installing a connection to my new workshop. (I used to be STROMA registered years back, will likely reregister to sign off myself).

16mm 3 core SWA is already run in ducting underground, correctly trenched in. The run is 10m end to end on the SWA.

I am not using the armour as the CPC.

The workshop end is glanded straight intl the CU, and wil be earthed.

The supply end will go from the meter to a 2 pole isolator on 25mm tails, into a henley block, where it will split to my existing domestic CU and into a 60A fused switch, still on 25mm tails.

The fused switch does not have the correct knock outs for the SWA, and it is to tight anyway to bend the SWA into it.
At the moment the SWA is gland sits in the brick wall, and the three conductors go in the mechanical proeltection white sheath, through a plastic cable gland into the switched fuse. The house end gland on the SWA will also be earthed, despite not strictly being required. All the house end stuff is inside a meter cupboard.

Is it acceptable to leave the SWA gland sat like this?

The bends will be too tight if I try to force the SWA round to a box. I did think about putting a steel plate on the wall and mounting the gland to that?

Photos attached, not.finished yet as the earths are not in place, and neither is the henley block, cable clips etc but you can see what I mean. Note that the existing CU is not my work, neither is all.the builders foam etc. All I have added is the small workshop CU and the fused switch.

Advice, thoughts, and constructive criticism are welcome.

 

[Fall-Apart-Dave]

Hello folks

Inhave my 18th Edition and Part P l, but I dont trade as a sparks.

I have a question about best practice for terminating SWA.

I am currently installing a connection to my new workshop. (I used to be STROMA registered years back, will likely reregister to sign off myself).

16mm 3 core SWA is already run in ducting underground, correctly trenched in. The run is 10m end to end on the SWA.

I am not using the armour as the CPC.

The workshop end is glanded straight intl the CU, and wil be earthed.

The supply end will go from the meter to a 2 pole isolator on 25mm tails, into a henley block, where it will split to my existing domestic CU and into a 60A fused switch, still on 25mm tails.

The fused switch does not have the correct knock outs for the SWA, and it is to tight anyway to bend the SWA into it.
At the moment the SWA is gland sits in the brick wall, and the three conductors go in the mechanical proeltection white sheath, through a plastic cable gland into the switched fuse. The house end gland on the SWA will also be earthed, despite not strictly being required. All the house end stuff is inside a meter cupboard.

Is it acceptable to leave the SWA gland sat like this?

The bends will be too tight if I try to force the SWA round to a box. I did think about putting a steel plate on the wall and mounting the gland to that?

Photos attached, not.finished yet as the earths are not in place, and neither is the henley block, cable clips etc but you can see what I mean. Note that the existing CU is not my work, neither is all.the builders foam etc. All I have added is the small workshop CU and the fused switch.

Advice, thoughts, and constructive criticism are welcome.

Also yes, I know the coloured sleeves are missing to correctly ID the cables too. These will be added.

 

[littlespark]

The SWA does need to be glanded properly at both ends, although the armour only needs earthed at one end if you’re using a core as cpc.

The gland isn’t done properly at the workshop. The “banjo” washer should be flat, with a hole drilled through into the enclosure. Then an M6 brass nut and bolt through the hole. From there, a short price of earthwire with a crimped end connects the banjo to the earth bar.

I don’t see why you couldn’t gland into the bottom of the switch/fuse…. Am I missing something?

 

[Fall-Apart-Dave]

The SWA does need to be glanded properly at both ends, although the armour only needs earthed at one end if you’re using a core as cpc.

The gland isn’t done properly at the workshop. The “banjo” washer should be flat, with a hole drilled through into the enclosure. Then an M6 brass nut and bolt through the hole. From there, a short price of earthwire with a crimped end connects the banjo to the earth bar.

I don’t see why you couldn’t gland into the bottom of the switch/fuse…. Am I missing something?

The switch fuse doesnt have a knock out the right size, and the bend is too tight to make it into there with the SWA. Believe me, I tried! Where the gland is, is where the hole through the brick wall is. There is no way thay swa will bend to the fused switch.

I bent the banjo trying to get it into the CU (originally it was coming in the top.but the SWA didnt want to play ball so went under instead). That will be put right when I fit the earth cable. But thank you for the reminder.

The SWA is already glanded both ends, you can see in the pics.

 

[littlespark]

That’s what holesaws were invented for.

If the knockout isn’t the right size, or in the right place, then drill your own hole.

Could you bush a metallic adaptable box to the bottom of the sw/fuse to give some sideways options of entry?

 

[Fall-Apart-Dave]

That’s what holesaws were invented for.

If the knockout isn’t the right size, or in the right place, then drill your own hole.

Could you bush a metallic adaptable box to the bottom of the sw/fuse to give some sideways options of entry?

I think if you saw it, you would see the issue. Hard through pics. Right sized hole or not... There just isn't the space to bend that SWA anywhere reasonable. I could always put an adaptable box over it and gland into the back. But then the gland is no longer accessible. Same issue with a steel plate.

Presumably then, the house end cannot be left as is? The gland must be attached to something? That SWA is going nowhere, its wedged and not somewhere that can be touched, and goes underground once it is through the wall.

 

[Fall-Apart-Dave]

That’s what holesaws were invented for.

If the knockout isn’t the right size, or in the right place, then drill your own hole.

Could you bush a metallic adaptable box to the bottom of the sw/fuse to give some sideways options of entry?

More pics for clarity.

 

[littlespark]

It can’t be left as-is, no. You can’t have the inner sheath (white) just exposed like that. Some makes of armoured cable, that sheath just crumbles off.

Great for terminating, but no protection for the cores outside an enclosure.


Out of curiosity, what size is that SWA, and the fuse size? (Fuse needs to be <= 63 to protect the RCD in the workshop box)

How big is this workshop?

 

[Fall-Apart-Dave]

It can’t be left as-is, no. You can’t have the inner sheath (white) just exposed like that. Some makes of armoured cable, that sheath just crumbles off.

Great for terminating, but no protection for the cores outside an enclosure.


Out of curiosity, what size is that SWA, and the fuse size? (Fuse needs to be <= 63 to protect the RCD in the workshop box)

How big is this workshop?

Ok. Would heat shrink or flexible conduit suffice? Does it even have to be double insulated? I mean, the grey sheath on twin + CPC is not for insulation but for mechanical protection and thats acceptable for leaving as is.

Im a bit stumped as to what to with it then other than comkng into the back of an adaptable box, or coming into the back of the fused switch and moving it down, both of which leave the gland inaccessible.

Its 16mm 3 core SWA. Fuse is 60A.

70sqm workshop.

 

[westward10]

As above you can't leave the white bedding exposed. Should have brought it into the back of the switch fuse.

 

[Fall-Apart-Dave]

As above you can't leave the white bedding exposed. Should have brought it into the back of the switch fuse.

Yes. Appreciate the advice. However, that is far easier said than done and leaves the gland inaccessible, and now I look there isnt a way of bringing it into the back of the fused switch, unless I open up the hole in the blockwork and seal the gland in the wall with mortar. putting the fused switch on the plasterboard means the meter cupboard wont close.

Its in a sealed cupboard. Perhaps pushing the gland further back into the void and putting plasterboard over it to create a recessed fused switch and hiding the whole lot behind there where it is inaccessible and cannot be seen?

Flexible conduit?

Heavy heat shrink? I have some that is used subsea down to depths of 3000m, impregnated with an adhesive.

Self amalgamating tape and scotchcote? Again, often used in deep sea electrical connections.

 

[Simon47]

My first thought was a metal box, gland into the back, bushing into bottom of switch/fuse. But I see you have a rather awkward layout.
Also, if you don't earth the supply end, you need to consider the fault impedance when that includes both the CPC core out and the wire armour back.

 

[brianmoooore]

Probably get the odd red 'X' for this, what what I would do, and did on one occasion, where there was little practical option, is to fit a galvanised adaptable box onto the SWA gland, fit a large stuffing gland to the box as well, slide off the outer sheath from some 25mm tails, and slide these over the L and N to the CU, trapping them in the gland.

 

[Fall-Apart-Dave]

My first thought was a metal box, gland into the back, bushing into bottom of switch/fuse. But I see you have a rather awkward layout.
Also, if you don't earth the supply end, you need to consider the fault impedance when that includes both the CPC core out and the wire armour back.

The supply end will be earthed. I just havent done it yet as I paused to ask for some advice.

I can see why the white sheath ideally should be covered but in truth, in this instance, cannot see how that may be achieved nor what real world proplem it would cause as it is.

 

[Fall-Apart-Dave]

Probably get the odd red 'X' for this, what what I would do, and did on one occasion, where there was little practical option, is to fit a galvanised adaptable box onto the SWA gland, fit a large stuffing gland to the box as well, slide off the outer sheath from some 25mm tails, and slide these over the L and N to the CU, trapping them in the gland.

Would this not be the same as putting flexi conduit over it? Singles in conduit are acceptable, I see nothing here that would be any different?

I have a galv box I can put on the gland.