Bends in conduit

[safedepth]

Afternoon all,

I have a need to run a new shower cable around the outside of a property. It is an 18 meter run. I've been researching the details in the OSG and BRB. So far happy, 10mm2 T&E. Propose to run in conduit. Only problem is the run requires about 11 bends in the conduit. If I'm reading it right the OSG doesn't like that and limits bends in conduit, see pg 120. However I can find no issues with it in the BRB.

Does anyone, (who doesn't!) know better?

Cheers

 

[Zeespark]

Just use round terminal boxes at the bends mate - nothing wrong with that as far as I am aware.

AndyGuinness

 

[steptoe]

you may have big problems pulling 10mm T&E through conduit with that amount of bends/corners, whichever way you do it.

25mm conduit at least,

I wouldnt want to be doing it,

could you use singles through the conduit?

 

[safedepth]

Just use round terminal boxes at the bends mate - nothing wrong with that as far as I am aware.AndyGuinness

Cheers,

Would look bloody daft with all of those terminal boxes over it though.

---------- AUTO MERGE Post added at 15:32 ---------- Previous post was at 15:27 ----------

you may have big problems pulling 10mm T&E through conduit with that amount of bends/corners, whichever way you do it.25mm conduit at least,

I wouldnt want to be doing it,

could you use singles through the conduit?

Thanks Albert,

Yes singles is definitely possible. I was going for 20mm as the run is predominately below the rendering bell mouth. 20mm would be more discreet. I know it's stretching the regs (522.8.2) but I was going to pull it in as I was constructing, simply because of the bends. Assuming the number of bends is not a regs issue. So many questions!

Cheers.

 

[steptoe]

singles then safedepth,

you wont get 10mm T&E through 20mm conduit and keep your airspace ratio, if it is even physically possible with your bends, 10mm through a straight length isnt easy(try it.).

I personally wouldnt have an issue with number of bends as long as you keep within the spacing regs.

 

[sparkytim]

Only reason to limit bends is to enable pulling in AFTER construction, normal method of wiring SINGLES in conduit.

You will have a job getting 10mm T&E in and round ANY bends in 20mm conduit, have just about managed it with 2.5 by slipping conduit and fittings OVER cable.

 

[safedepth]

singles then safedepth,you wont get 10mm T&E through 20mm conduit and keep your airspace ratio, if it is even physically possible with your bends, 10mm through a straight length isnt easy(try it.).

I personally wouldnt have an issue with number of bends as long as you keep within the spacing regs.

I assume by spacing regs you mean the cable rating within the conduit?

 

[batty]

Outside wiring looks bad how about using SWA?

 

[steptoe]

yep, we used to go on an airspace ratio,

if you can use singles then I think you will be OK,

otherwise it would prob be a no no,

I havent worked anything out though,

Im still thinking that 10mm T&E is NOT going to physically fit anyway.

and TBH, it will prob be enough to pull in 10mm singles, you are going to need easy bends.

---------- AUTO MERGE Post added at 16:24 ---------- Previous post was at 16:23 ----------

Outside wiring looks bad how about using SWA?

^^^^^^+1

good thinking bat(ty)man

 

[safedepth]

Outside wiring looks bad how about using SWA?

As usual the money.

Customer's daughter has shower this morning. Loud bang and smoke from airing cupboard. Call's me out and I find a horrible mess of what's left of the switch.

They think it will need a new fuse but the shower was run in 4mm T&E. The shower is only an 8Kw model but in my opinion it's still right on the limit, added to that is I don't know the installation method. New loft conversion and the cable runs under the flooring of that. Who know's what's in there.

I've proposed a new cable, lovely decor throughout means externally run.

She'll have enough of a shock when she sees my quote with Singles. I'm expecting SWA to be a lot dearer. Or would it not?

Any views?

 

[batty]

Swa installation time would be a lot quicker I would think you must have

 

[PC Electrics]

I was going to suggest split con or swa or even H07RN-F. Depends somewhat on what you consider the risk of mechanical damage to be. Over this sort of distance the ease of installation is much more an economic factor than the cost per metre.

 

[rugbymacc]

time spent doing it t/e in conduit will be alot......

swa will be easier to install ......

so really the total price of mats and labour should be about the same on both methods of install ?

 

[safedepth]

What are people paying for 10mm SWA right now?

 

[batty]

Not sure don't buy large swa very often TLC are advertising 10mm 3 core swa for

 

[Riggy]

I realise I risk lots of people shouting at me here, but how sure are you that the 4mm T&E is a problem?

Unless the mains voltage is very high, most 8kW showers will happily run on a B32 MCB. I'd be trying to find out a bit more about current installation method I think.

 

[safedepth]

I realise I risk lots of people shouting at me here, but how sure are you that the 4mm T&E is a problem? Unless the mains voltage is very high, most 8kW showers will happily run on a B32 MCB. I'd be trying to find out a bit more about current installation method I think.

Riggy,

I understand your concern and here goes.

From Page 131 in OSG current carrying capacity is 36a if clipped direct, i.e. best case. As I said I can't be sure of the installation method, this coupled with the fact that the cable has already deteriorated and has burnt out once, and pure safety has lead me down this route.

After all when I have left this installation one of the following will apply.

1. It is now safe and compliant.

2. The customer has found another sparks who has offered to do it cheaper and i must forage elsewhere for the kids dinner money!

3. The customer has chosen to install a new plumbed shower.

Whichever, I will be able to sleep safe in the knowledge that I did all I could. As we know there is almost always someone to do it cheaper. Maybe reusing the existing cable is possible, but without proving the installation method it's not for me. As I said earlier, the decor is pristine throughout.

 

[PC Electrics]

Riggy,I understand your concern and here goes.

From Page 131 in OSG current carrying capacity is 36a if clipped direct, i.e. best case. As I said I can't be sure of the installation method, this coupled with the fact that the cable has already deteriorated and has burnt out once, and pure safety has lead me down this route.

After all when I have left this installation one of the following will apply.

1. It is now safe and compliant.

2. The customer has found another sparks who has offered to do it cheaper and i must forage elsewhere for the kids dinner money!

3. The customer has chosen to install a new plumbed shower.

Whichever, I will be able to sleep safe in the knowledge that I did all I could. As we know there is almost always someone to do it cheaper. Maybe reusing the existing cable is possible, but without proving the installation method it's not for me. As I said earlier, the decor is pristine throughout.

Just make sure you let the client know why you're recommending a new circuit. So that when bodge it Bob says he'll reconnect the old one, they will doubt his competance.

 

[safedepth]

Just make sure you let the client know why you're recommending a new circuit. So that when bodge it Bob says he'll reconnect the old one, they will doubt his competance.

Very good point,

thanks PC.

:Salute :Salute

---------- AUTO MERGE Post added at 18:04 ---------- Previous post was at 17:57 ----------

Not sure don't buy large swa very often TLC are advertising 10mm 3 core swa for

 

[batty]

Very good point,thanks PC.

:Salute :Salute

---------- AUTO MERGE Post added at 18:04 ---------- Previous post was at 17:57 ----------

Just did calc's for 6mm SWA. Volt drop would be >5% so will stick with 10mm SWA. Shame as current carrying capacity was well up for my needs.

Always the volt drop that kills it.