New sockets in workshop

[Fireblade]

Hi All

First post, so hope it's in the right place and I've followed all the rules...!!

Been asked to quote on a job which in the workshop of a car dealership. Job is to provide x2 new socket outlets. Original installation has numerous three phase DB's, not to mention all the steel conduit throughout the workshop for all the obvious reasons.

My thoughts are to avoid having to fit new steel conduit but to run 2.5mm 2 core SWA (utilising armour as CPC) from an existing switched double socket to a new switched FCU and then feed x2 double sockets as a radial from the new FCU again in 2.5mm SWA with the amour utilised as the CPC.

Any thoughts/comments

Cheers

 

[robsparx]

That sounds fine to me except I'd use 3 core swa, using one of the cores as the earth.

And do you know what they're plugging into the sockets? If the 2 sockets have a limit of 13A, that might not be enough for what they're being used for

 

[Hawk81]

As long as the sockets are rcd protected then all sounds good to me and welcomE to the forum!

 

[robsparx]

Oh yes and what he said ^^^. Probably the most important part lol

 

[Adam W]

Welcome to the forum!

Would it be possible just to extend the rings in steel conduit so it's in keeping with the original installation?

 

[bugsy]

As prev stated 3c swa S/O c/w 30m/a RCD,s - welcomevto the forum

 

[telectrix]

as said before, prefer use 3 core, but must earth armour as well. as the cable itself does't need RCD protection, you could use 2 twin RCDsockets, thus increasing the load capacity. instead of the FCU.

 

[nickblake]

Welcome to the forum , It would be nicer in steel conduit as has been said , but SWA in 3 core with RCD protection shouldnt be a problem test existing conduit to ensure earth continuity ,Galve through box terminate SWA there connect earths ,run to sockets SWA protected by Conduit connection ,jobs a good un

 

[Hawk81]

as said before, prefer use 3 core, but must earth armour as well. as the cable itself does't need RCD protection, you could use 2 twin RCDsockets, thus increasing the load capacity. instead of the FCU.

Surely the FCU will still be needed to stop the spur being a spur off a spur. I too would use 3 core swa.

 

[telectrix]

Surely the FCU will still be needed to stop the spur being a spur off a spur. I too would use 3 core swa.

don't think the OP mentioned existing circuit was a ring final. i assumed it was a radial.

 

[Hawk81]

don't think the OP mentioned existing circuit was a ring final. i assumed it was a radial.

I assumed it was a ring and that was why the op was fitting an FCU.

 

[telectrix]

in fact, we should never assume .capt. edward smith assumed the titanic was unsinkable., look where that got him.

 

[Hawk81]

in fact, we should never assume .capt. edward smith assumed the titanic was unsinkable., look where that got him.

Very true!

 

[telectrix]

actually, it would be logical for it to be a ring.. as a radial, unless in 6mm would be pretty useless in a garage workshop, due to the loads required.

 

[Hawk81]

actually, it would be logical for it to be a ring.. as a radial, unless in 6mm would be pretty useless in a garage workshop, due to the loads required.

True maybe the op will tell us which it is. My money is on ring.

 

[Adam W]

Aren't we assuming that the sockets are going to be used for some kind of mechanical equipment and not for an office area in the corner, and therefore wouldn't need rcd protection as it's surface mounted, protected by earthed metallic sheath and being used by skilled or instructed operatives?
Unlikely, but it was unlikely the Titanic would sink.

 

[Adam W]

My money's on 'ring' as well, hence "then feed x2 double sockets as a radial from the new FCU".
If it was a radial anyway there would be no need to specify - you wouldn't add a ring to a radial.

 

[flukey]

im with novus

 

[Hawk81]

My money's on 'ring' as well, hence "then feed x2 double sockets as a radial from the new FCU".
If it was a radial anyway there would be no need to specify - you wouldn't add a ring to a radial.

Exactly the point I was making.

 

[Fireblade]

Hi Guys....

Wow, didn't expect so much feedback and so quickly - only popped downstairs for my dinner!!

Yes, it's a final ring with RCD protection.
Client is not worried about esthetics and therefore SWA will be fine.
Loading is low, hence a 13A fuse will surfice - however, I think I will hard wire in equipment to prevent some "dumb dumb" plugging goodness knows what in the future!!!

Am very keen to know why the general feeling is that 3 core SWA is a the route to go - surely earthing the amour and then having the third core as earth is beyond what is required. More than happy to take your advise but am interested as to what the rationale behind it is?

Look forward to your comments.....

Cheers

 

[keefy]

Hi Fireblade,

3 core SWA is usually prefered as the armour cannot always guarantee sufficient CSA to withstand a fault current. For a 2.5 SWA, you need to calculate the minimum size of the CSA of the SWA (k1 over k2 x S) and you get 7.77mm. 2.5 has 17mm CSA of SWA so that is well in. Some cables (10mm 2 core for example) do not comply once calculated so many people are adverse to installing 2 core, especially on 230V where 3 core is easy to use instead. However, you try getting the stuff. I have just had to wait a week for 50M of 2 core 6mm!

Even if you do use 3 core you should still fit the earth tags, bolts and some cpc. And on sockets that can sometimes be tricky if you are going side entry or have a few cables in the one box. For short, straight runs steel conduit or bush & coupling would be better. I recently saw a job where there was 6 sockets lined up on a wall 1M apart, all had short runs of SWA between them. Ughh, Ugly and no doubt time consuming to make of so many ends.

Hope that clears things up... or muddies the water further.

 

[Knobhead]

Do it in conduit! It will fit in. Plus there’s pride in the job

 

[malcolmsanford]

Do it is conduit as Tony says it will be in keeping with the rest of the installation, ....................and use the conduit as your CPC if it is suitable.

If your determined to use SWA then for crying out loud use a 2 core and the SWA as the CPC. What will be the maximum size of the CSA 1.5mm off a FCU and if your going to use normal 70c type PVC then you need an SWA equivilent of approx 3.5mm to equate to a copper conductor, and the CSA will in fact give you 15mm

 

[somersetsparks]

I would use 2-core, if your gonna go to the trouble of banjos etc. might as well use the armour, scratch the paint off from behind the locknut and fit serrated washers is what I would do, rather then banjos, they are a right pain on metalclad sockets if you have more then one cable.
3- core is way OTT really, although cost difference is probably negligable.
I would also always use a CW type gland personally, they are much better quality generally, and then you get less condensation rusting the armouring especially in workshops!

 

[Hawk81]

Do it is conduit as Tony says it will be in keeping with the rest of the installation, ....................and use the conduit as your CPC if it is suitable.

If your determined to use SWA then for crying out loud use a 2 core and the SWA as the CPC. What will be the maximum size of the CSA 1.5mm off a FCU and if your going to use normal 70c type PVC then you need an SWA equivilent of approx 3.5mm to equate to a copper conductor, and the CSA will in fact give you 15mm

I dont know if it is just me or if anyone thinks the wording in this reply is a bit ott. saying things like "if you are determined" and "for crying out loud" is not needed. espcially when you are saying it over something like the use of 2 core or 3 core. its not like using 3 core was going to make the job any less safe. also if the op wants to do it in swa that is their choice. This is a new member to the forum and talk like this might not encourage them to return with more questions. Well thats my opinion anyway.

 

[Adam W]

I dont know if it is just me or if anyone thinks the wording in this reply is a bit ott. saying things like "if you are determined" and "for crying out loud" is not needed. espcially when you are saying it over something like the use of 2 core or 3 core. its not like using 3 core was going to make the job any less safe. also if the op wants to do it in swa that is their choice. This is a new member to the forum and talk like this might not encourage them to return with more questions. Well thats my opinion anyway.

Well I didn't agree with any of that post - I would use 3 core not 2 core, I wouldn't use the armour or conduit as the CPC (especially for a final cct) and Tony wasn't the first to suggest extending the installation in conduit.
... And yes the language could be considered harsh but of course everyone is entitled to their opinion regardless of how much I disagree with them.

There's some guy who comments on the stories in my local paper and always seems to feel the need to express his opinion as "completely" this, "totally" that and "absolutely" the other. I think it makes someone's view sound overly opinionated, but again that's just me. Maybe he's just gone "utterly" butterly.

 

[flukey]

if the cable complies, which 2 core does then that would be my choice if i was to use swa, but as previously said i would be more inclined to stick with conduit as per existing install

 

[malcolmsanford]

I dont know if it is just me or if anyone thinks the wording in this reply is a bit ott. saying things like "if you are determined" and "for crying out loud" is not needed. espcially when you are saying it over something like the use of 2 core or 3 core. its not like using 3 core was going to make the job any less safe. also if the op wants to do it in swa that is their choice. This is a new member to the forum and talk like this might not encourage them to return with more questions. Well thats my opinion anyway.

I have to say to start this that if I caused any offence to the op then that was defrinately not my intention as in his original post he was wanting to use 2 core SWA for a 13amp sub circuit of a final circuit via a FCU. If he did think I was OTT to quote your reply I do appologise as he got the circuit design spot on.

The for "crying out loud" was meant at you and the 4 or 5 others trying to convince him that for a small SWA feeding 2 sockets required a dedicated conductor, and then we get the tome from another poster which had no bearing at all on this thread or question.

If people can not be bothered to design a circuit correctly using calculations, then that is fine if that is their choice., but the OP designed his correctly and then was advised that a 3 core would be better, my question is why? What advantage would a 3 core SWA give him in this scenario?

The remark about doing it in conduit still stands. Perhaps it was the elder members on here that advised him to do it in conduit as it would be keeping in the style of the existing installation. I still believe he as made the wrong choice in SWA, but that is his choice and that is that.

To the OP I sincerely hope I didn't offend you and if I did I appologise unreservedly, to the posters who were trying to persaude you from not installing to your perfectly acceptable design................I'll leave it there.

 

[mogga]

SWA into a metalclad socket (assuming m/C ) as Assumption is rife in this thread ) your best bet would be Bush n coupling as the gland encroaching into the socket depending on manufacturer will leave no room for face plate to fit

 

[Hawk81]

I have to say to start this that if I caused any offence to the op then that was defrinately not my intention as in his original post he was wanting to use 2 core SWA for a 13amp sub circuit of a final circuit via a FCU. If he did think I was OTT to quote your reply I do appologise as he got the circuit design spot on.

The for "crying out loud" was meant at you and the 4 or 5 others trying to convince him that for a small SWA feeding 2 sockets required a dedicated conductor, and then we get the tome from another poster which had no bearing at all on this thread or question.

If people can not be bothered to design a circuit correctly using calculations, then that is fine if that is their choice., but the OP designed his correctly and then was advised that a 3 core would be better, my question is why? What advantage would a 3 core SWA give him in this scenario?

The remark about doing it in conduit still stands. Perhaps it was the elder members on here that advised him to do it in conduit as it would be keeping in the style of the existing installation. I still believe he as made the wrong choice in SWA, but that is his choice and that is that.

To the OP I sincerely hope I didn't offend you and if I did I appologise unreservedly, to the posters who were trying to persaude you from not installing to your perfectly acceptable design................I'll leave it there.

I think if you read my first reply again you will see I told the op his design was fine. It was only later that I said that I would use 3 core and I still stand by this. I do not understand why you are so against 3 core. Hardly any price difference and surely having a dedicated core is. Safer. I was in a workshop recently where the sockets were done in 2 core and the second socket on a 4mm. Radial had the gland broke out of the metal box and the other 5 sockets had no earth.

 

[malcolmsanford]

I have nothing against a 3 core SWA and utilising that 3rd core as a CPC, if by design the SWA is not capable on it's own to provide a good enough conductor. In this scenario a 3 core of say a 1.5mm armoured would, by utilising a 3rd core as a cpc will be 1.5mm. If you utilised the SWA as the CPC then you would have the equivilent of 15mm which is in my mind vastly safer.

I can not comment on the installation you have outlined, as bad termination and installation can be achieved with any kind of containment. I have lost count the amount of times I have removed a face plate and the earths, lives or neutrals have fallen out, or indeed been out, does that make cable and a screwed termination a poor design?

I can only say that a correctly terminated SWA into a gland and then that gland terminated correctly, and I'll use the banjo as the example, then believe me that cable will not come out by accident or any other influence other than the deliberate removing of it by intention.

Would you run a 3 core MICC cable as you would not feel uncomfortable with utilising the outer sleeve as a CPC? Most electricians would say no, that is crazy, but have no problems with runing a 3 core SWA because it is safer.............absolute poppycock, it's not safer it is easier than sitting down and doing a design where you would need to think.

 

[Engineer54]

Why change the installation method??? The whole of this workshop sounds as if it's been professionally kitted out in Galv conduit, (and rightly so too) ...Along comes a DI who has never touched conduit of any type, and thinks that SWA is the way to go to extend a ring circuit!!! Any electrician worth his sort, wouldn't think twice about not continuing the present galv conduit installation..

These days, it seems if it's not T&E /capping or SWA then they are buggered, and will do anything to use a form of wiring that is easier to install, even if it's to the detriment of the existing installation. .....I guess that's what they call progress these days!!!! USE GALV CONDUIT for god's sake !!!

 

[somersetsparks]

Just to add my 2p worth.
The OP designed a perfectly acceptable installation, personally though I too would use conduit in a workshop as swa can get pulled of the wall pretty easily, especially when the cleats have gone a bit britlle, however the OP has to win this job so I imagine he has to keep costs down etc. and without looking its hard to say what I would do exactly.

As for the argument about 2 or 3 core, I would always use 2 core for single phase, where the CSA is adequate, its good solid engineering, and the cores are the right colour.
Banjos - I was always led to believe that banjos were for enclosures which had no earth termination or placcy enclosures. I always use serrated washers, scratch away the paint and do the gland up TIGHT.
I have seen loads of jobs where they have banjos all over the shop linking to the eath terminal which is joined to the same bloody enclosure but the glands are only finger tight anyway! You wouldn't go linking everything with pyro would you?
On some jobs I have been on recently, to keep unnecessary costs down, they have had conduit and trunking systems with no earths at all. Keeping costs down, think 1/3 off cable cost (probably 1/2 million saved over whole job), Huge amount off conduit and trunking cost due to less cable and a cheaper job for customer.

 

[Engineer54]

Just to add my 2p worth.
The OP designed a perfectly acceptable installation, personally though I too would use conduit in a workshop as swa can get pulled of the wall pretty easily, especially when the cleats have gone a bit britlle, however the OP has to win this job so I imagine he has to keep costs down etc. and without looking its hard to say what I would do exactly.

I don't think it has much to do with costs, ...as material wise, conduit in all likelihood would be cheaper. Labour may be more expensive, without the skills required. But if the skill is there, then conduit would be probably go in just as quick as the SWA, but even if it takes a little longer, ...it's well worth the effort!!!

 

[Hawk81]

Why change the installation method??? The whole of this workshop sounds as if it's been professionally kitted out in Galv conduit, (and rightly so too) ...Along comes a DI who has never touched conduit of any type, and thinks that SWA is the way to go to extend a ring circuit!!! Any electrician worth his sort, wouldn't think twice about not continuing the present galv conduit installation..

These days, it seems if it's not T&E /capping or SWA then they are buggered, and will do anything to use a form of wiring that is easier to install, even if it's to the detriment of the existing installation. .....I guess that's what they call progress these days!!!! USE GALV CONDUIT for god's sake !!!

I am very confused by your answer here. Firstly how do you know the op is a DI? Is there any need for you to speak to anyone the way you have in your reply? yes i agree the galv conduit would look best but that is only an opinion and there is absolutely nothing wrong with the design by the op. Saying things like "for gods sake" is no help to anyone. Recently i have saw people complain about the elitist attitude on this forum and I am starting to see it myself now. You are one of the main reasons I see it. The way you have answered alot of posts is degrading to many others and I am not the only one to notice.. The use of CAPITALS and !!!! makes it seem like you are shouting and who give you the right to come on and shout at anyone. It is not a nice way for a new member to see the forum. Maybe if you answered with more manners your suggestions might be listened too.

 

[Engineer54]

I am very confused by your answer here. Firstly how do you know the op is a DI? Is there any need for you to speak to anyone the way you have in your reply? yes i agree the galv conduit would look best but that is only an opinion and there is absolutely nothing wrong with the design by the op. Saying things like "for gods sake" is no help to anyone. Recently i have saw people complain about the elitist attitude on this forum and I am starting to see it myself now. You are one of the main reasons I see it. The way you have answered alot of posts is degrading to many others and I am not the only one to notice.. The use of CAPITALS and !!!! makes it seem like you are shouting and who give you the right to come on and shout at anyone. It is not a nice way for a new member to see the forum. Maybe if you answered with more manners your suggestions might be listened too.

There's nothing elitist about wanting to see the standard of installations in the UK remain high!!! I see far too much of those once high standards being systematically neglected and diminished...

But maybe your right, i can sometimes be too blunt in my thoughts and opinions... If so i appologise...

 

[keefy]

I think if you read my first reply again you will see I told the op his design was fine. It was only later that I said that I would use 3 core and I still stand by this. I do not understand why you are so against 3 core. Hardly any price difference and surely having a dedicated core is. Safer. I was in a workshop recently where the sockets were done in 2 core and the second socket on a 4mm. Radial had the gland broke out of the metal box and the other 5 sockets had no earth.

It seems Malcolm is intend on pushing his opinion that the more money you save, the better the job. Maybe you should let people be Malcolm and do the job as they prefer, as long as it is done well and safely surely that is the most important, not about picking hairs; having an extra core in the SWA. As I previously mentioned in this post, it is actually difficult to get 2 core these days, and when you do it is not that much cheaper as it is a special and no more difficult to install. This forum, I was under the impression, is meant for discussion debate and sharing of knowledge, if you want to show off your superior knowledge, try doing it in a polite, informative way in future.

 

[Hawk81]

There's nothing elitist about wanting to see the standard of installations in the UK remain high!!! I see far too much of those once high standards being systematically neglected and diminished...

But maybe your right, i can sometimes be too blunt in my thoughts and opinions... If so i appologise...

Fair enough. It was not your ideas that I was saying were elitist but the way you put them accross.