Running Cable In Ducts

[jlperry]

Hi all,

Can you run normal 1.5 mm and 2.5 mm twin & earth cable in a duct under the ground, or does it have to be SWA?  Cheers

 

[Technician]

Have a look at table 4A1 in the BGB.

Then tables 4A2.

Does not ALWAYS have to be armoured,

but you must consider external influences.

 

[Evans Electric]

It seems a bit strange but I've certainly seen references to doing that .    I always imagined they meant an accessible duct with a cover ,  Isn't there a picture of such thing in the Regs .

Just had a look.

522.8.10  says yes if the duct offers protection against mechanical damage.

 

[steptoe]

Id be concerned about water ingress, rodent damage etc,

but, so long as the duct is properly sealed and IP rated and mechanically sound and strong enough I see no reason why a T&E couldnt be run within one.

 

[Zeespark]

Many moons ago, I was running fibreoptic cable in underground ducts underneath the taxiways of Heathrow Airport. If fibreoptics can be run in ducts, I cant see why T & E cant be.

Andy Guinness

 

[Sidewinder]

Again the only reason. I can think of is that I personally don't like the idea, but, I can't see any reason why not.

Would I?

If I had to, yes, I suppose I would!

I would suggest that external influences are fully considered, and the note to Reg 522.8.10 is considered carefully.

 

[Steve3948]

I thought the duct/tube had to be earthed, or did I dream that when doing an installation when asleep  :Blushing

 

[Andy™]

I thought the duct/tube had to be earthed, or did I dream that when doing an installation when asleep  :Blushing

it is earthed... unless your installing it overhead

 

[Steve3948]

Plastic duct how ?

iirc  Any suitable cable enclosed in conduit or duct which gives at least the same degree of mechanical protection as an armoured cable.

 

[Evans Electric]

I thought the duct/tube had to be earthed, or did I dream that when doing an installation when asleep  :Blushing

Sounds like a nightmare Steve .

 

[batty]

I did a rewire years ago and a previous sparks (commercial) had run power up the garden in conduit I think it was singles but possibly TW/E. Now this was shorting out  so a new armoured had to be installed. The only way I would be happy if it was proper electric cable duct and it had no joins in it.

 

[Evans Electric]

Regs may be leaning towards a duct with cover , within a building , like a heating pipe duct .

This has reminded me of a jobsworth of a design  eng. on a large boiler room refurb from coal to gas .    A narrow duct across the front of the  three huge boilers ( think Titanic)   was installed by builders to carry cables to the burners at the fronts.   Cables were SWAs ......he wanted them clipped to the side of the duct ..can't do it , too narrow to drill & fix  so he insisted they were fixed to the floor of the duct .  

You just think ....why .... where does he think they will be going ?  Bloody pedant.