Unconventional termination of SWA

[PaulieN]

Here's one for you all.....

I've been retired from the electrician game for over 20 years now, but back in the day when using smaller sizes of SWA that needed to be terminated into a plastic enclosure CU I'd often treat the cable like a concentric with regard to dealing with the armour. I'd dress and twist it, usually into a couple of neat conductors, sleeve it properly and run directly into the boards earth block. I would add that I'd only do this indoors of course in a plastic enclosure and 100% of the strands were always used.

I know a lot of you will be spitting feathers by now, but how is this not actually better than having a bulky brass gland and ring floating about in the CU, the high resistance risk of clamping through plastic, or another ugly steel box bolted nearby to terminate into? It's arguably safer too, having only one termination, as opposed to at least three in the event of using the traditional methods with the increased risk of adding resistance into the earth path at each termination point, especially as we're talking about steel strands here rather than copper!

OK, I'll get my flack jacket and await your replies, bet I can't get a valid argument against this apart from a perception of it being "rough"... 

 

[binky]

if the gland is correctly installed, it provides a good electrical path to the SWA. What you are suggesting is electrically sound, but I would think rather impractical, especially given the small terminal holes in modern CU earth bars, to me it seems harder work than using a gland. 

 

[PaulieN]

I suppose it's academic now as if installing a new circuit in SWA to a CU, it seems the current regs would require a change of said CU to metal clad anyway. Is that correct?

I am a bit rusty lol!!

 

[Murdoch]

I suppose it's academic now as if installing a new circuit in SWA to a CU, it seems the current regs would require a change of said CU to metal clad anyway. Is that correct?

I am a bit rusty lol!!

No cu change required

Are you sure you were a spark

 

[Evans Electric]

Yes it would be metal now  , however  I've seen quite a  few  small   2.5  X 3 core  SWA's connected like that  in plastic boards  ,  no need for the flack jacket in my opinion .  

No different to the split - con that feeds a house really ,  no glands used . 

 

[Jono Pashley]

No cu change required

Are you sure you were a spark

No need to be like that really is there. Guy is retired and out the loop no need for it.

 

[Andy™]

No need to be like that really is there. Guy is retired and out the loop no need for it.

dont think his previous method was acceptable before he retired either

 

[Jono Pashley]

dont think his previous method was acceptable before he retired either

Just like taking a swipe at a member and not even nothing with their question isn't acceptable this isn't facebook.

Done in the manner the bloke describes it's far from ideal but as the question asks is it really any less safe. Arguably not, although for anything bigger than a 2.5 you would lose half the earth bar to terminate all the strands. I wouldn't do it myself but it was quite common around here in the past.

 

[PaulieN]

Well I think I still am an electrician lol!, although haven't practiced since 1994, so yes, I'm very out of the loop.

@ Andy, There's an answer I was expecting! So tell me why this is so much worse for small SWA than having a large brass gland rattling around inside a plastic CU (if the cable came in from behind for example) with a total of 4 connections between the armour and earth block as opposed to my 1!  

@Jono Pashley, Why is this considered far from ideal, whilst if it was a split concentric, it would be perfectly fine? Not being leary, just genuinely interested to know why you think that?

 

[Andy™]

SWA & split con are completely different cables and designed to b terminated differently

whilst its not a method i would use or recommend, it probably would be electrically sound

 

[Tony S]

I’ve forty years as an industrial electrician, we’ll forget the couple of years as a production manager. I’ve now been retired ten years.

I’m sorry but if you terminated a SWA as you suggested in your opening post you wouldn’t last five minutes with me. The SWA should be made off as in metal containment, the gland earth tag (until I joined a forum I’d never heard of them referred to as banjo’s) is your earth.

As others have said, concentric and split concentric are totally different animals. Made off badly they look a mess

 

[PaulieN]

I’ve forty years as an industrial electrician, we’ll forget the couple of years as a production manager. I’ve now been retired ten years.

I’m sorry but if you terminated a SWA as you suggested in your opening post you wouldn’t last five minutes with me. The SWA should be made off as in metal containment, the gland earth tag (until I joined a forum I’d never heard of them referred to as banjo’s) is your earth.

As others have said, concentric and split concentric are totally different animals. Made off badly they look a mess

Again though, give me a reason why this is bad practice, other than you don't like it. I agree, made off badly it would look a mess. None of my work ever looked a mess, it was always exceptionally neat. Why is a direct connection to an earth block worse than going through several connections to get there? It is neither electrically, or in the case of being inside a plastic enclosure, entering from the rear, aesthetically worse than the official method of termination? Remember I'm only advocating this in the case of small cables in plastic enclosures in a residential situation where the official method isn't practical, or would aesthetically look a mess. Using this method, it can be done exceptionally neatly.

 

[Andy™]

Remember I'm only advocating this in the case of small cables in plastic enclosures where the official method isn't practical. It can be done exceptionally neatly.

thats odd. ive managed to connect many small SWA's imto plastic enclosures and the official method of using a proper SWA gland has always worked and been the most practical

 

[PaulieN]

So, in the case of the cable entering from the rear of the unit, you have the brass SWA gland within the unit, yes? Well fine, but again, give me an actual reason why this is better than what I've suggested, either electrically, or for other reasons other than, "it's just not how it's meant to be done" or you just don't like it... Please remember, I'm not suggesting it should ever be done outside, or in any other situation where the normal method is suited.

 

[Tony S]

OK, you have twenty 2 core 1,5mm² SWA’s to make off in to a marshalling cabinet, what are you going to do?

I know what I would do.

 

[Andy™]

cables are brought into the side

but no point arguing. youve already decided how you were going to do it anyway, even if it is a bodge and something a DIYer would do

 

[PaulieN]

So, you have an existing plastic CU, it's on a beautifully tiled wall and you need to get a SWA into it that's running up the other side of the wall. Without making a hideous mess of the customers decor, the cable is going to have to come through the wall through the back of the unit. Would you really bring it through elsewhere and then terminate through the side of the unit??

Again, you keep throwing out how it's a bodge, but nothing to back up why you think that or giving a valid reason of why it might actually be less safe than the conventional method. 

 

[roys]

Much like Tony I was 35 years as industrial spark and also now retired, I have to say I wouldn't even consider using anything other than a proper SWA gland on a SWA cable, in fact even the cheap glands from the like of Screwfix annoy me a little but they are better than nowt, I was use to Hawke 501 universal gland which is a "proper" gland.

The long and short of it is, use a SWA gland after all I would hazard a wild guess that the manufacturer of the SWA gland would say that in their instructions, I would be very surprised otherwise.

As to your example of tiled walls and other such examples, I have always found a way, one of my usual is to fit a 75x75 metal box next to the consumer unit as a point to gland to but use it as a through box so the only termination is made in the consumer unit. The JB would be bushed between itself and consumer unit with a lock ring or two in between to give a bit of lid clearance.

 

[Sidewinder]

PaulieN,

Welcome to the forum.

That method is not in compliance with the cable standards, as in the British Standards for the cable, I have checked, and yes I have checked the old versions.

It would not be compliant with BS 7671 back as far as the 15th in 1983, I can give you the relevant regulation numbers if you like.

As far as current practice goes.

It is not necessary to replace a plastic CU when undertaking modifications.

Your method of termination would not comply with 134.1.1, 134.1.4, 511.1, 522.8, 512.15, 512.2, 543.3.201, you would have to meet 120.3, 133.1.3, & 511.2

 

[PaulieN]

An actual reason!, thanks for that, so looks like I was wrong after all back in the day