Discuss Underground SWA (does this have to be in a duct?) in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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Edward Amsden

I have a installation to carry out in a new building and the hotel maintenance and office staff have agreed that the supply (SWA) to this building (the hotels responsibility) needs to be in a pvc ducting as secondary mechanical protection. Along with 2 fire alarm cables.

I aint fussed but is the duct necessary. SWA and electrical warning tape!? that is what i believed the minimum was.

I spoke to the bloke and he said it was linked to a ducting manufactures website... and thats why they are doing it.

I looked in the 17ed regs and its a bit lacking. What's the score. Please!!
 

Brightspark2

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SWA can be buried directly in the ground with no further protection at sufficient depth as to prevent damage...

BUT would it not be worthwhile putting a duct in for future cables?...I dont know the scenario but always useful for future cables if its building to building etc.

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telectrix

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if the client wants ducting, then give him ducting. he's paying for it.
 

Guitarist

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If you want to make sure that there is a layer of sand under your swa, followed by more sand or sifted soil on top, in order to prevent sharp stones penetrating the outer sheathing, then no, you don't need ducting.
If, however, you want to dig a trench and wack the cable in, then ducting is ideal :)
 
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Edward Amsden

He has put it in. Isnt my problem, I would just like to know the answer when someone else asks and I say no a duct isn't needed but some office waller says I found a link to this website that sell duct and they say you need to buy some really expensive land coil and use it as a duct!
If all swa needs to be in a duct then ok. I don't want to cut corners but I don't want to loose work either..
The duct was bedded in sand as well. More than a 16mm cable would ever need! lol
 

telectrix

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there is no requirement for SWA ro be ducted. but as guitarist said, it should be protected from sharp things by cocooning in sand.
 

Mfctitch

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I'm with telectrix if the customer wants it let him have it.
At the very least give him a price.
Just wondering how was you going to run the two fire alarm cables?
 
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1shortcircuit

If I was to do this and decided a duct was needed I would also insert a draw cord out of the kindness of my heart for the next poor sod that had to pull another cable in at a later date.

What goes around comes around an all that;)
 
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Engineer54

I have a installation to carry out in a new building and the hotel maintenance and office staff have agreed that the supply (SWA) to this building (the hotels responsibility) needs to be in a pvc ducting as secondary mechanical protection. Along with 2 fire alarm cables.

I aint fussed but is the duct necessary. SWA and electrical warning tape!? that is what i believed the minimum was.

I spoke to the bloke and he said it was linked to a ducting manufactures website... and thats why they are doing it.

I looked in the 17ed regs and its a bit lacking. What's the score. Please!!
Believe me, it is a far easier job having a SWA in a duct than direct burying it, if there is only one or two of you. The potential for sheath damage to cable(s) if direct burial is not carried out correctly is almost a certainty. Are these fire alarm cables also SWA??

No sure why you want to go with ''Minuimum'' when the client wants a higher than minimum installation? They have all my compliments, it's a rarity these day's that a bigger sized client is prepared to spend that little extra on an installation, even when it will afford them a little flexibility in the future....
 

benji

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is there more than one duct don,t like to see power and fire alarm/data in same duct


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Edward Amsden

Only one duct.
The original agreement was the company I was working for put the duct and cables in for the fire alarm and the hotel made provisions for the supply. (i think they were just going to lie the cable in the sanded trench which is 600mm-900mm deep)
In the same trench is also a 8 inch flow return heating pipe.
I didnt like them insisting on all three going in one 110mm duct. Its a 16mm 5 core swa..

As people have pointed out if they want to put a duct, then put a duct in. The maintenance guy insisted that all swa hast to be in a duct. I didn't argue with him as he is the customer, the regs are a bit unclear to say the least and i was hoping someone on here may be able point me in the right direction to a reg that covers it.
 
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