red ducting in basement for moving mains

[daz1963]

Hi all. hope someone can point me in the right direction.doing a rewire for two flats above a shop which is straight forward enough. except the mains are being moved from the front of the shop to the rear. the dno want three switched fused isolaters installing at the rear and a 115mm red ducting installed in the basement about 450mm from the basement ceiling for the new mains cable to run in. whats the best way to mount the duct.only had experience in ducting in the ground.is there any special brackets that someone could point out to me?the distance is about 12 meters. as the mains are being moved to the back and the shop consumer unit is about 12 meteres away at the front is it ok to run 25mm tails on say a cable tray from one of the switched isolaters back to the front of the shop. i assume swa would be best but its a insulated consumer unit and room is tight to swap back to a adaptable box.the specified switch fuses are 80a for the shop and 60a for the flats and is a tn-s system.
many thanks in advance...
Daz...

 

[Guest55]

I'd fix the ducting using bendy metal strapping screwed to the basement ceiling , every 1 metre if its rigid ducting , 0.5 mts if flexi.
Yes double insulated tails on tray will be fine.

*Metal straps availible from most builders merchants

 

[daz1963]

Thanks Biff.That would certainly make it easier, was thinking on the lines of unistrut,but that makes it a bit more complicated as i really havn't had much to do with there stuff.

 

[johnboy6083]

Unistrut is child's play mate. Ask for a brochure on what fittings are available, and draw the shape you require. Then you work out what fittings you need.
I don't like the idea of suspended ducting though. I would prefer deep tray with lid, but there again you have to go with what the DNO want.

 

[telectrix]

why red ducting? surely trunking would be more appropriate.

 

[yellowvanman]

Isn't there any plumbing type brackets that would fit?

 

[johnboy6083]

Munsen rings.

 

[daz1963]

why red ducting? surely trunking would be more appropriate.

Hi Tel. Thats what the dno specified.to hang from the basement ceiling,through the shop and then through about 5 foot of concrete to come up through the back floor.

 

[Andyfm]

Done a similar thing through a bank basement years ago, and had to use 4" threaded conduit/pipe which was fun.

I suspended it from the ceiling with large clamp type fittings which were screwed on to studding fixed with a bracket

 

[sparkydude]

Definiteley get them to confirm what sort of ducting they want you to install for them as last time we put a cable duct in for the leccy board it had to be 4 inch cast iron painted with red oxide . They will have a spec for what they want you to install for them, and do not deviate from that otherwise jobsworths will makle your life hell .

Nick