Doubling up 2.5 T&E for workshop electrics

[Avo]

Hi,

My new workshop is around 16 meters from house CU. I have a 50mm plastic pipe run underground to the workshop with 2 x 2.5mm T&E cables run through it. I would have run swa 4mm but the cables were already in so I'm making use if them.

Question: What current capacity does 2 x 2.5 doubled up give me at 16 meters buried around 14" in a pipe?

Is it possible to achieve the following safely?

2 x 16A circuits for sockets (protected and unprotected).

1 x 5A for lighting. The lighting is low voltage led type.

So is it feasible or have I to make sacrifices?

Thanks guys.

Danny

 

[Evans Electric]

You need a SWA installed , there is no earthed protection to your plastic pipe.

You may be able to draw a SWA through the pipe by hooking on to the 2.5s as its a 5* mm pipe .

 

[Badger]

agree with evans swa / armoured for the laymen :slap is whats required. not the twin and earth thats in at the moment. sorry but you should be looking at doing things correctly, and not bodging it im afraid youll have to get 4mm armoured minimum. and 20 amps is good on 4mm at that distance, just a word of warning what type of supply do you have, tns/pme/tncs/tt?

 

[ProDave]

And 14" is a bit shallow, it's supposed to be at least 450mm or 17" deep.

You should have asked before you started I'm afraid.

Ideally SWA laid in a bed of sand, with yellow "electrical cable" warning tape above it.

 

[Apache]

You guys are taking the micky I assume?

2.5mm T&E is capable of handling up to 24A. Even with a 0.7 correction factor you have ((24*2)*.7) = 33.6A

http://www.tlc-direct.co.uk/Book/4.3.5.htm

What is you expected demand out there? My shed has a 16A and a 6A and I never get to use that much. You want to plug in a power-drill and a lawnmower or are you running a kiln?

What is your earthing arrangement.

Earthing plastic pipe, Deke! Naughty!

 

[Andy™]

Hi,My new workshop is around 16 meters from house CU. I have a 50mm plastic pipe run underground to the workshop with 2 x 2.5mm T&E cables run through it. I would have run swa 4mm but the cables were already in so I'm making use if them.

Question: What current capacity does 2 x 2.5 doubled up give me at 16 meters buried around 14" in a pipe?

Is it possible to achieve the following safely?

2 x 16A circuits for sockets (protected and unprotected).

1 x 5A for lighting. The lighting is low voltage led type.

So is it feasible or have I to make sacrifices?

Thanks guys.

Danny

i hope its not a water pipe... if anyone damages it in the future, i doubt they would be happy at getting a shock from a water pipe that you threw a cable in

 

[ProDave]

i hope its not a water pipe... if anyone damages it in the future' date=' i doubt they would be happy at getting a shock from a water pipe that you threw a cable in[/quote']I was doing a new build for a dumb builder once. having been instructed to leave a "duct" for the electricity cable, the DNO rightly refused to thread their incoming cable through the bit of blue alcathene water pipe the builder had supplied.

 

[needasparks]

As others have said its not really designed to go outside as pvc absorbs water so even though it will be in a tube condensation will form inside and cause problems later.

I don't think i personally would have a problem about the depth if it was swa with an earthed sheath even though it is recomended to be alot deeper as long as there will be no chance of damage in its location.

 

[Chr!s]

Hi' date='My new workshop is around 16 meters from house CU. I have a 5*mm plastic pipe run underground to the workshop with 2 x 2.5mm T&E cables run through it. I would have run swa 4mm but the cables were already in so I'm making use if them.

Question: What current capacity does 2 x 2.5 doubled up give me at 16 meters buried around 14" in a pipe?

Is it possible to achieve the following safely?

2 x 16A circuits for sockets (protected and unprotected).

1 x 5A for lighting. The lighting is low voltage led type.

So is it feasible or have I to make sacrifices?

Thanks guys.

Danny[/quote']

You have several issues, one is that of current sharing upon load and under fault conditions.

For mechanical protection, See 5228.1* Underground conduits/ducts may be made of many materials,Steel, Earthenware, Polypropylene etc.Cables not incorporating and earthed sheath may be installed within the above.

All ducts need to be suitable marked.

HSE recommend depths of between 45*mm - 1***mm.

 

[Evans Electric]

Why are the zeros showing as *** ???

 

[SLIPSHOD & SLAPDASH]

As others have said its not really designed to go outside as pvc absorbs water so even though it will be in a tube condensation will form inside and cause problems later.I don't think i personally would have a problem about the depth if it was swa with an earthed sheath even though it is recomended to be alot deeper as long as there will be no chance of damage in its location.

So whats SWA cable made from then ?

 

[needasparks]

So whats SWA cable made from then ?

Think you will find its make up is different for BS6**4 cables than in swa. hence why it is more affected by UV sunlight loses its colour and cracks. we just group them up as PVC as a term.

A girls pvc mini skirt would look strange with copper in it.

 

[Evans Electric]

Ref; Plumbers post.

I have to say that the BRB Table 4A2 (page 265) does indeed show unarmoured cable used underground. Duct material is not refered to.

Its not a thing I have ever considered doing TBH .

 

[sb_89]

@ badger T-n-c-s is PME , just saying lol

 

[Andy™]

T-n-c-s is PME , just saying lol

TNCS is not always PME.

 

[sb_89]

Do elaborate

 

[Andy™]

could be CNE

 

[philbas]

Do elaborate

Very good explanation here

http://www.talk.electricianforum.co.uk/student-learning-zone-c-g-233*-levels-2-3-c-g-2381-c-g-2391-other-co/1548*-simplified-earthing-arrangements.html

at least when the link works

The first sticky in the student and learning forum.

 

[sb_89]

Good link, helpful

 

[Avo]

Well, I never installed the cable as I said. It was already in place, as I said.

I also said I would have run 4mm swa, problem is I can't get it down the conduit now as there are two bends at both ends that are too tight... Even if I remove the t&e.

The pipe isn't blue water pipe, it's some black stuff from builders depot.

After talking to the installer it appears it's buried deep enough, it was more like 2' deep.