Armoured cable terminations

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blastcleaner

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Is it permissable to terminate an armoured cable in / onto a plastic enclosure?

I understand the need for the wire shield to be earthed, and the need for continuity of earth, and the need for mechanical strength of the enclosure, but I want to put a switch disconnector in line joining 2 armoured cables, mounted on a wall, rather than a huge switch fuse box.

The alternative is a metal switch disconnect but as the amperage increases the prices multiply.

On the other end I want to put a 5 way CU and RCD, same question, plastic or metal?

Thanks

 

gazza96

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I have, I wasn't using the Steel Wire as the CPC, it was 3 Core, 2.5mm so used the cores as Phase (Line), Neutral and CPC.

The box was an enclosure IP rated 56, Plastic Grey

 

Alzee

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Can't you just link the frying pans supplied with the gland kits? I'm assuming you got SWA cable gland kits, you know, with lock nut, shroud (maybe) and frying pan.

If the glands are being fitted side by side you could just link both frying pans together with a brass nut and bolt, if not then link with say 6mm sq earth wire.

This linking can be done either inside or outside of the enclosure.

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.

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I don't think you can use the armour as your cpc earth but it should be earthed also.

 

DonkeyDong

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Hi there,

nothing wrong at all in using plastic enclosures with SWA - as long as the enclosure is mechanically suitable (strong enough) and you correctly terminate/earth the armour if required - using the earth tags (fry pan as someone called it on here :^O )

I had to make off 38 terminations the other day - luckily in 2.5mm 3 core. Some of them were into pladtic enclosures, they others into steel. Even though not always needed, I always use tags with a trailing earth lead.

D.

ps - Its perfectly acceptable to use the armour as a CPC - as long as it meets the requirements for that circuit (I now use a core and the armour as the CPC, unless there is a substantial cost difference).

 
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blastcleaner

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Thank you everyone, really helpful, especially the double lock nuts incase the caseing is compressed so continuity of cpc is ensured.

Further question arises from a DVD I bought from NICEIC called Periodic inspection and testing, domestic property 1930's, they identified an earthing clamp on the sheathing of the incomer (terminoligy may not be quite correct, but you get my drift) as a BS951 safety electrical connection, but said it was not suiteable for this application, so what should be used as a bonding clamp here? Does it mean it should be something chunkier?

Thanks again

 

DonkeyDong

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hi,

it means that if the existing sweated/soldered earth terminal onto the main incomer is no longer suitable, then you can't use it. There is no clamp or connector you can use to remake that type of connection - its not your property. You will either have to change the tns to tt, or get the elec board out to convert it to tncs or maybe they might repair the tns.

Those clamps you mention are purely for sup bonding purposes onto pipes.

D.

 
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Although Donkey is correct you will find that on a large number of TNS supplies there are BS 951 clamps that were put there by the supply company !!! What the Niceic are saying is a clamp is not suitable for an armoured or lead sheathed cable. Remember TNS has not been installed for around 35 years now and things were not enforced as much then as today. A 951 clamp is better than nothing and i have never found a loose one or a high Ze because of one.

 

steptoe

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on a similar, but different vein,

any pointers on a decent set of amoured cable shears, my old ones are just about bit the dust, less effort to use a hacksaw now!!!!!

anything that will do 25/35mm 4 core would be more than adequate for most of my use.

thanks, Albert. :x

 

steptoe

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Agreed in principle , but in the real world as my earlier post ;)
would totally agree slips,

but have you ever found a dead short because of one either?

thought not, and i bet the poor guy that caused it wont ever do it again either.

bit late after you make that last sweet turn just to make sure.

remember, we are in full view of publc here and IMHO perhaps thats a tips and tricks idea, joe public with his T handle screwdriver may not be as astute as us to sweeten it up and leave alone.

 

blastcleaner

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Further question arises from a DVD I bought from NICEIC called Periodic inspection and testing, domestic property 1930's, they identified an earthing clamp on the sheathing of the incomer (terminoligy may not be quite correct, but you get my drift) as a BS951 safety electrical connection, but said it was not suiteable for this application, so what should be used as a bonding clamp here? Does it mean it should be something chunkier?
Thanks again for all the replies.

 
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BS951 clamps DO state clearly on the the box that they should not be used for lead - i.e. TN-S!!. "technically",it is up to the DNO, not you, to provide an earth terminal on the incomer, although they don`t always, as has been previously discussed:(

Suggestion would be to attempt to get DNO to provide earthing terminal. If you talk VERY nicely to their engineer on site, he may give you a couple of their clamps:x:x:x

 

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