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johnston1991

Terminating SWA at plastic Comsumer Unit

Question

hi all,

just a quick one please probaly sounds daft but.. what are the preffered ways to terminate SWA at a plastic consumer unit??:| metal clad box then tails up to it ? the SWA is 2 core and im using the armour as earth for the sub main and TT'ing the second consumer unit.

cheers

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depends on CU... some can take a SWA, some cant (mostly IP rated that can). if you can terminate into it, use a metal box below and take cores straight through into CU

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When I do garage/sheds I usually use a volex five way Rcd protected consumer unit. I tend to use 10mm two core swa as this is adequate for most needs. I cut armour back with swa stripper and then put swa through

25mm nylon gland. I then TT building. I find you can get a 25mm large nylon gland straight into a volex consumer unit. It maybe possible with other makes but I have done a lot with volex with no problems. I used to get them from bdc but have had to find a different supply. Screwfix do a 5 way main switch one which you could then change switch for RCD as they do a 80a 30mA RCD.

I have also used MK consumer units in the past as these can take a 25mm gland but are a slightly dearer option.

Batty

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Oh Batty , why can't you get them from BDC anymore ? ;););\;\

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Oh Batty , why can't you get them from BDC anymore ? ;););\;\

not sure. i think we need a BDC thread to find out why

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I have on occasion terminated swa into insulated cu's, MK / Wylex & Crabtree ranges.

Use these to make life easier http://www.tlc-direct.co.uk/Main_Index/Earthing_Index/Piranhna_Earth_Nuts/index.html

The other option is as you say terminate into adaptable box below or next to cu the run cores straight into cu.

If I'm TT'ing a submain from a pme supply I use insulated adaptable box.

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Either SWA gland straight into the plastic CU (if its a decent one) or plastic/steel adapta box.

D.

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thanks for all the replys should be a lot of help whn i coem to use it, the consumer unit is just a cheap mk sentry 6 way board from screwfix so may be a bit iffy shall wait and see

thanks :)

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Has anyone started a BDC thread yet?

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Has anyone started a BDC thread yet?

behave!

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Why is everyone talking about BDC all of a sudden , What can it mean ?

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use a 3 core armoured as the swa only requires earthing at one end and use a stuff in gland on the plastic cu............not my method just an idea as i prefer to use split con cable as its a lot easier

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Oh Batty , why can't you get them from BDC anymore ? ;););\;\

hmmmm?

did they go into administration Deke??/:O]:):P;\

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Why is everyone talking about BDC all of a sudden , What can it mean ?

perhaps the rumours are true people are buying from them again??:(Blushing

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use a 3 core armoured as the swa only requires earthing at one end and use a stuff in gland on the plastic cu............not my method just an idea as i prefer to use split con cable as its a lot easier

Here's a question on split concentric cable since it's been mentioned.

For those that use it, you will undoubtedly know what the British Standard number is. Can you tell me if it is one that BS7671 refers to as a recognizable cable? My reason for asking is that I have been informed it doesn't and that is to only be used by distributors. Where do you find the tables for volt drop, technical data etc?

I know that NAPITs view is it is not to be used.

Thoughts?

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There may be a mix-up here . A split concentric cable has a single inner core (Live) The concentric cores are copper , half of them were insulated in black PVC the other half insulated in green. No need for a gland. AFAIK we were allowed to use them.

A concentric cable ,as used by the distributors, has all the concentric wires uninsulated, they use it for PME and merely split it at the cut-out. You can't use it on installations.

I have worked on installations which where TNC throughout the project. This was done using single core bare pyro (MICC) with earth tail pots. Its done to save money I believe, this was a huge project, but as I remember, Home Office approval is required.

To connect a socket , centre core was live, the earth tail looped , continuous, to the back box ,the neutral and the earth.

The metal dist. bds. had no neutral bar, just an earth bar bolted to the case.

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make it TNC and use pyro to save money??? could do it cheaper with T&E and normal earthing!

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I wouldn`t be happy terminating swa into a stuffing gland, TBH. As for the concentric debate, I didn`t think it was recognised by 7671 for installations - though I`m not certain, which is why I didn`t post.

Clarification ( with reg) would be appreciated?

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Fixed Wiring and Mains Cables - SPLIT CONCENTRIC - Plain annealed stranded copper phase conductor, XLPE insulated surrounded by a concentric layer of plain annealed solid copper neutral conductors. XLPE insulated and plain annealed solid strand bare copper earth conductors, PVC outer sheath. Black. 600/1000 volts grade to BS7870

heres the links

http://www.clevelandcable.com/products.asp?id=2271&step=2&catid=20

http://www.batt.co.uk/products/view/610/Split-Concentric-Cable-BS7870

ive been installing it for over 8 years as sub-mains and street lighting both the napit and niceic local engineers are happy with it during their annual inspections

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I wouldn`t be happy terminating swa into a stuffing gland, TBH. As for the concentric debate, I didn`t think it was recognised by 7671 for installations - though I`m not certain, which is why I didn`t post.

Clarification ( with reg) would be appreciated?

SWA into stuffing gland does sound a bad idea - if anything, at least a gland on the end of the armour.

split con has been used for many years - ive used it myself for submains etc - much easier to terminate and work with than SWA

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Well BS 7870 does not appear in appendix 1 of BS 7671.

Also I had a chat with NAPIT technical about it and as I stated previously, their stance is that they recommend it is not used. I'm referring to both cables, so there is no confusion.

When looking up BS 7870 it states:

LV and MV polymeric insulated cables for use by distribution and generation utilities.

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I thought concentric cables where only used by dno. I personally have never used it only time I have come across it was on a recent job at some stables where a long bit had been used between meter and stables not a good idea as the cable had no cpc. As for using stuffing glands on consumer units why not. If it is pme and you use a standard swa gland you are not going to be able isolate house earth from shed or outbuilding earth. I always TT outbuildings that is why I use a nylon gland that way the house earth is seperate to the shed earth.

Batty

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I thought concentric cables where only used by dno. I personally have never used it only time I have come across it was on a recent job at some stables where a long bit had been used between meter and stables not a good idea as the cable had no cpc. As for using stuffing glands on consumer units why not. If it is pme and you use a standard swa gland you are not going to be able isolate house earth from shed or outbuilding earth. I always TT outbuildings that is why I use a nylon gland that way the house earth is seperate to the shed earth.

Batty

your getting a bit mixed up... there are 2 types of concentric cable - straight and split - straight con has a centre core and all uninsulated outer cores and is only used by DNO for TT or PME supplies. Split con has a centre core, half outer cores are insulated for neutral, and half uninsulated for earth - can be used as a submain, or you could even use it instead of T&E. can also be sued by DNO for TN-S supplies

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andyc,

Are you deliberately ignoring my replies to this thread?

Google BS 7870

LV and MV polymeric insulated cables for use by distribution and generation utilities.

Correct me if I am wrong, or preferably point me in the direction where it states it's suitability to be used by consumers as it has no reference in BS 7671.

The links that have been posted by 0151 do not even mention which parts of BS 7870 the cable complies with.

Not looking for a fight, rather some clarification :)

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your getting a bit mixed up... there are 2 types of concentric cable - straight and split - straight con has a centre core and all uninsulated outer cores and is only used by DNO for TT or PME supplies. Split con has a centre core, half outer cores are insulated for neutral, and half uninsulated for earth - can be used as a submain, or you could even use it instead of T&E. can also be sued by DNO for TN-S supplies

So is it cheaper than standard swa because unless it is I can see no other reason for using it.

Batty

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So is it cheaper than standard swa because unless it is I can see no other reason for using it.

Batty

not always cheaper, but easier to work with so time savings can be more than additional cost

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