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PaulieN

Unconventional termination of SWA

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kerching

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

 

just saying

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Evans Electric
On 11/10/2018 at 22:12, roys said:

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 . 

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Evans Electric
14 hours ago, kerching said:

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. 

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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".

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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.

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Onoff

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

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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.

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kerching
7 hours ago, Evans Electric said:

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

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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?

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Evans Electric
23 hours ago, kerching said:

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  :-  

Scan0001.jpg

Edited by Evans Electric

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Tony S

Carp lyrics but 10 out of 10 for the sentiment.

 

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SLIPSHOD & SLAPDASH
On 14/10/2018 at 00:19, Evans Electric said:

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. 

shopping.png,,

 

We had to use these 100% of the time on   BT jobs, that was about 15 years ago. I wonder what H&S would   say today.

 

Back to the op, what about street lighting cutouts, no glands & a jubilee clip round the swa.  I was taught a similar method,  on my apprenticeship, slipping a pipe under the swa and a jubilee clip in certain   tight areas, 

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Evans Electric

OH  BT were using them too then !  

 

Yes street lighting was a problem we had too .  Wiring in SWA  , a metal spur was spec'd  to be fitted inside the lampost service point  but you couldn't get two pair of grips in there to fit a gland  .  The only way was to have a big loop sticking out , gland up onto the box and shove all the slack  into the lampost .   Having a loop in & out was even worse .  

These were the more decorative lamposts  , not much room,     used for university campus   pedestrianised areas and walkways  , hundreds of 'em .       That was the job we asked about using split concentric   and were informed we were not allowed to install it .   

I'd bet if the city council  or the local electric  board  were doing the job ...they'd have used it !!!    

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Evans Electric

Talking about unconventional  termination of SWA's    ...I just remembered  doing some work for British Gas  on their remote stations  .   

 

Their method of making off SWA   was the usual way ,  row of armoureds in the top of a panel  ....then about  6 - 8 inches  above the gland  they cut a band of PVC out of the sheaths  about 20mm wide  and strap all the SWA 's together with copper strip  clamped onto the armouring .  :C

 

I didn't emulate the method as I thought it was stupid TBH   .

 

They did however have a great method with their  really high   lighting columns .   Attach  this hydraulic device at the bottom ,  shove a lever in to lift the top half of the column off the base , then lower it against the hydraulics  .     Do your work on the floods at the top then pump it back up .   

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Tony S
9 hours ago, SLIPSHOD & SLAPDASH said:

 

Back to the op, what about street lighting cutouts, no glands & a jubilee clip round the swa.  I was taught a similar method,  on my apprenticeship, slipping a pipe under the swa and a jubilee clip in certain   tight areas, 

 

It’s a very common way of terminating SWA’s, the “top hat gland” supports the cables armouring. I had many an argument with E54 about them.

 

A few years back I had to look in to having 11kV PILC-SWA cables terminated, top hat glands and heat shrink tubing to the rescue.

 

5 hours ago, Evans Electric said:

 

Their method of making off SWA   was the usual way ,  row of armoureds in the top of a panel  ....then about  6 - 8 inches  above the gland  they cut a band of PVC out of the sheaths  about 20mm wide  and strap all the SWA 's together with copper strip  clamped onto the armouring .  :C

 

 

Very common back in the 60's.

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Evans Electric
3 hours ago, Tony S said:

Very common back in the 60's.

Who  was that then   Tony  ?  This was British Gas  .   Can't say I ever saw it done until  the 1990's . 

 

My thoughts on it were :- 

1.  What does it achieve ?  Nothing . 

2. The glands  &  banjo's bolted to the top plate were more than adequate  and conformed with common practice .

3.  Exposing the armour wires to the elements  is not to be recommended  in any way . 

4.  Squashing  the cores with a clamp is not common practice .

 

Edited by Evans Electric

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Tony S

I can think of a couple of companies I’ve worked for that used copper tape between SWA’s. It doesn’t mean I agree with the method. When I first saw it used I couldn’t see the point of it and I still can’t.

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Evans Electric
3 hours ago, Tony S said:

I can think of a couple of companies I’ve worked for that used copper tape between SWA’s. It doesn’t mean I agree with the method. When I first saw it used I couldn’t see the point of it and I still can’t.

Its as pointless  as those  PVC conduit adaptors  with a moulded boss on the side .     Apparently its for a self tapper to fix an  earth lug  to :C 

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kerching
7 hours ago, Evans Electric said:

Its as pointless  as those  PVC conduit adaptors  with a moulded boss on the side .     Apparently its for a self tapper to fix an  earth lug  to :C 

Well I actually thought it was for sticking a self tapper in to "lock" the conduit in the "style of the 'American system " where they do not thread the conduit 😂

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Evans Electric

It could be  that ....  I just  remember asking  and thats what I was told .    I'm surprised they still do that moulding TBH  .      Hey!  Thinking about it ...  isn't there a boss in the PVC  conduit boxes  for "earthing"   ?   

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kerching
10 hours ago, Evans Electric said:

It could be  that ....  I just  remember asking  and thats what I was told .    I'm surprised they still do that moulding TBH  .      Hey!  Thinking about it ...  isn't there a boss in the PVC  conduit boxes  for "earthing"   ?   

 I think you can buy a terminal to push fit into it for joining the earth wires together

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Pete10001
On 11/10/2018 at 12:44, PaulieN said:

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, gland the SWA into the enclosure as normal, use a Piranha lock nut and earth the Armour via a suitable size lead from the nut to the earth bar, as you normally would 

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