Unconventional termination of SWA

[PaulieN]

You have still failed to offer any industry recognised guidance backing up your method, you have referenced no regulations applicable either then or now that suggest your method is acceptable. By your own admission you consider it would not comply with BS7671. What happens a few years after your SWA has been fitted and A.N.Other has the board opened to do some alterations/additions/fault finding/testing etc.. the "inside" bit of your joint is open and accessible to mechanical strain whilst undergoing work inside the CU. Its not just about someone pulling the cable from outside. During the normal expected lifespan of the installation and the cable you have installed, it is quite probable that persons other than yourself could be working in or around your SWA. The whole concept of your joint is liable to mechanical damage, and/or damage to other cables in the enclosure as it is not properly terminated. It is bad enough working in a CU with a rats nest of PVC cables, the last thing you need is a SWA hanging around in the board as well, with loads of strands of relatively inflexible steel armour strands twisted and cluttering the earth bar. I would consider this to be a potential danger to any person working in the enclosure at a later date. So rolling back 20 odd years, you probably should have been applying, 130-01-01,  130-02-01 as a bit of basic good practice and common sense. Just because you cannot see a danger, does not mean there is none, and the very title of your thread implies you know that. The bottom line is that we do not have to prove it is electrically unsafe or dangerous etc. But you as the "competent installer" have to be able to prove it is safe, and compliant with the relevant regulations, which so far you haven't.

Doc H. 

I've already conceded  I'm starting to remember the other reasons other than I stated in my post above that I was glad to see the back of the profession!

 

[Jono Pashley]

Just incase anyone comes across this and wonders how it should be done.

 

[Evans Electric]

I guess the "Unconventional Termination of an SWA "    is'n't far removed from  through jointing  some extra cable  to it . 

No glands involved  and  strapping the  armour wire together  by shoving a jumper of  suitable earth cable  under two Jubilee clips around the armouring.   

I think  this has gone as far as  it needs . 

I know one thing kids don't do anymore  with SWA   and thats  if they're being left outside for a long period  they don't seal the ends .  

I went a job where the customer's father in law "knew everything "   He'd laid an  SWA   a year ago , left lying in the garden  until this garage was finally erected .

I  told the customer I'd got to cut about 10 metres  off it  as capillary action  had drawn water all along & ruined the steel wire  which was to be used as earth . 

He thought I was ripping him off  as the father in law knows everything   so I  left them with it .  

 

[Phoenix]

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.

View attachment 9659

I'd order the cabinet with a brass gland plate inside on the bottom, cabinet and gland plate to be pre-drilled with the right amount of holes for the cables that are going in.

Actually, just thinking about it, what would make it even better, is if they used thicker brass, and tapped the holes to M20, then could dispense with the lock rings and tighten the glands straight into it

 

[Tony S]

I'd order the cabinet with a brass gland plate inside on the bottom, cabinet and gland plate to be pre-drilled with the right amount of holes for the cables that are going in.

Actually, just thinking about it, what would make it even better, is if they used thicker brass, and tapped the holes to M20, then could dispense with the lock rings and tighten the glands straight into it

Been there, done that. The trouble is, it's not cheap.

 

[Evans Electric]

what would make it even better, is if they used thicker brass, and tapped the holes to M20, t

Blimey Phoenix,    posh job or what  !!!     I think if you were quoting ,  that ready tapped plate alone  would lose you the job .  :innocent

 

[Evans Electric]

I raised this  a while ago , thought it could take another airing   on the subject of SWA's.

Another firm did some work at a place I go to regularly ,  a load of SWA's  terminated in a board  ...with the banjo's  on the inside ,  which I'd never seen in over 50 yrs .

I understood the point of a banjo was to increase the surface area of the gland onto the plate . 

 

[binky]

never understood why banjos get installed outside the box, especially in damp areas where corrosion may be an issue

 

[roys]

never understood why banjos get installed outside the box, especially in damp areas where corrosion may be an issue

Makes non intrusive inspection of earthing easier

 

[Evans Electric]

never understood why banjos get installed outside the box,

To increase the surface area of the gland ,  is what we were told .         Its strange  you say that ,  I , and anyone I know in the trade  since the 1960's  have never seen them on the inside ....perhaps it changes by  location .   :C

There are a few  anomalies that you come across perhaps once only .

One I always quote  was a hospital  wards refurb we did ...the spec demanded  the use of , when coupling to a surface box...a flanged coupler   ( steel conduit)   complete  with long reach 20mm bush with a serrated washer on it  .on the inside   ....and a lead washer  between the flange & the box .     All very well  but never , ever did it again .

This was B/E conduit  but theres a Google picture  so someone must still use them ...shows the lead washer but not the serrated washer. 

,,

 

[kerching]

I've installed hundreds maybe even thousands of flanged couplings...but never seen one with a serrated washer

just saying

 

[Evans Electric]

we would still be doing daft things like trying to Earth window frames.

Ah  those balmy , bygone days  of yore  when consultants & designers suddenly  viewed window frames as a danger to life  .   :innocent          I remember doing at least two new jobs  where it was spec'd.       The first job, the apprentice broke the first window by drilling  where the glass  sat in the rebate  .    

Second job the architect demanded to know what all these wires were doing , sticking out the plaster in all the window reveals .  We then received  a site order to cut them all off &  the missing plaster patched up . 

 

[Evans Electric]

I've installed hundreds maybe even thousands of flanged couplings...but never seen one with a serrated washer

just saying

Really !!!   Only ever used them once  .   Boxes were the surface   MK  2004 ALM  type  with flush plates .     Hospital saddles , flanged coupler with lead washer on the outside  & long reach bush with serrated washer on the inside .  

We observed the consultant  on numerous occasions , when thinking he was alone ,   wrenching at our switch drops to check the bushes were tight .  

Another once only spec.  was working at  Cadbury's   in Bournville  .....( I could see the logic it) ...fix a fuseboard to the wall  then seal round it with mastic  to prevent  insects taking up residence  behind it .  Also  hospital saddles so that grime  & shyte doesn't collect behind the conduit .

Also , long before the overall ban ,  no smoking ,,anywhere on site. 

Also eat as much chocolate  as you  want but under no circumstance put one in your pocket .

Also a Cadbury's  Hazelnut Whirl  can be used  in place of tallow / cutting paste. 

 

[OnOff]

I thought a lead washer compresses a bit and seals the entry. The serrated washer years ago was for ensuring continuity if reliant on the conduit. 

CEF do M20 zinc plated serrated washers. Stock No is SW20 presumably meant for SWA hence the "SW".

 

[Tony S]

Serrated washers were for the inside of the containment and the banjos the outside in my days. I suppose everything has changed now.

 

[OnOff]

I mainly come across serrated washers now on proximity sensors. Weird sizes like M18 so I try not to lose them!

 

[binky]

serrated washers are suppossed to act like a spring and prevent unwanted losening of the nut, same as a spring washer, but with the added advantage of digging into painted surfaces.

 

[kerching]

Ah  those balmy , bygone days  of yore  when consultants & designers suddenly  viewed window frames as a danger to life  .   :innocent          I remember doing at least two new jobs  where it was spec'd.       The first job, the apprentice broke the first window by drilling  where the glass  sat in the rebate  .    

I think it was around then that I did the 15th course, I think this was the first as I never recall doing a 14th ( so,this is when the gravy train left the station)

it was advised, when bonding radiators, to drill the bottom flange and fit a nut and bolt

I think a few were daft enough to try it

 

[Big Blue Bulb]

For my money, the greatest concern would be the compatibility of the steel armour wire with the earth terminals, for making a permanent connection. Normal screw terminals are designed for plain copper or tinned copper wire, which compacts and flows to form a gas-tight metal-to-metal interface with the terminal. The steel armour is much more rigid and may not come to rest in a compact enough formation in the terminal to prevent oxidation and/or loosening in the future. The design of an SWA gland provides multiple independent contact points on the surface of the brass cone that can deform slightly into contact with each strand, whereas a plain screw terminal has only the end of the screw. A cage clamp does not have any points of very high pressure as it presents flat surfaces to the cables being clamped. I wonder whether the makers of the terminals would have sanctioned their use with galvanised steel wire?

 

[Evans Electric]

I think it was around then that I did the 15th course, I think this was the first as I never recall doing a 14th ( so,this is when the gravy train left the station)

    I started  with the 13th  in force ...  employed back then ......  the 14th  seemed to creep in  un-noticed , we  eventually bought  the Guide  to the Regs  .

First full regs book I owned was   the 15th   ... we  formed Complete Electrical Services then  but none of us went back to college  for it .  

The  16th  I look on as the "Gravy  Train "  pulling out of the station  and building up  steam  as it leaves the Toll Gate  on  the Rock Island Line .

The 17th  saw it  rattling over the gaps ..."Sausage & chips ..sausage & chips "     powered by steam & funded by  Sparky's  cash    .

The 18th  and the "Gravy Train"   hits the flatlands of Illinois  with the throttle  fully open ,  and she's heading for glory with her bullion cars loaded with Sparky's cash !!!

Theres a song there somewhere ....  

She pulled into Birmingham one cold December day 

As she pulled into the station you could hear all the Sparkys say 

That train is full of Regs books , it's long and its tall 

And we're spendin' a bleedin' fortune on that Gravy Train cannonball  .

Four chords & it's a folk song .  

As employees  all we ever bought were these  :-