Advice on Pulling 6 mm2 single core cable through 20 mm Conduit

[Maximus Rumpas]

Hi,

I would like to ask your advice about how difficult it might be to pull cables through 20 mm plastic conduit. (easy, moderate, hard, impossible)

I am running two separate lines for a cooker and hob in 6 mm2 single core stranded cable. Both runs will follow the same route.

4 meter run from distribution board via 90 degree inspection bent to an inspection box next to soil stack.

Next 2.5 meter run through Bathroom/Kitchen wall to an inspection box under sink (minor set to allow for wall levels)
Then either
4 meter run, chased into wall via 90 degree inspection bend to a third inspection box.
or
4 meter run via 300 mm drop to Floor level - two 90 degree inspection bend to the third inspection box.

Lastly 1.5 meter run to cooker or hob isolation switch.

On completion permanent access to inspection boxes - limited access to 90 degree inspection bends.

Your thoughts please.

Kind regards
Max

 

[Sintra]

Mate they make conduit in larger sizes than 20mm. I would go 25mm.

 

[Maximus Rumpas]

Thanks Sintra,

Due to limited clearance in some areas I would like to avoid using a larger conduit if it were possible to use 20mm. If the advice is that it is impractical then I will have to use a larger size.

Max

 

[gazzaabc]

I'm not understanding you? Can't you just tell us how many cables are in any one conduit and the sizes of the cables? You will struggle with 6mm in 20m conduit a specially with a bend. I think that's a no go

 

[ayjay]

you need 25mm and a spring to bend it and some lube
or use singles,not twe

 

[gazzaabc]

Lol@ the lube technique fairy does the trick every time. U will get 10mm if you use fairy lol jokes

 

[Maximus Rumpas]

Hi Gazzaabc,

I thought I had - separate feeds to cooker and hob in 6 mm2 single core stranded cable Live, neutral and a smaller earth. Three cables in total in one conduit run. I thought I might struggle and that I should go for 25mm but wanted to check first.

Kind regards
Max

 

[Maximus Rumpas]

Hi ayjay,

Never mentioned twin and earth. Question stated single core.

 

[gazzaabc]

If the earth is smaller you will defo get 3 cables down a 20m pipe if only 2 of them are 6mm. You won't even struggle

 

[gazzaabc]

Max if your using plastic pipe you can buy 2 types of elbows! Buy the larger type. it's a bigger and longer bend but its not as harsh on the bend as the smaller one and makes life a lot easier.

 

[Sintra]

If the earth is smaller you will defo get 3 cables down a 20m pipe if only 2 of them are 6mm. You won't even struggle

OP stated "I am running two separate lines for a cooker and hob in 6 mm2 single core stranded cable. Both runs will follow the same route." I am taking this as 2 circuits 6 x 6mm singles.

 

[Maximus Rumpas]

Hi Sintra,

O, I see how I might have confused you, sorry. One run for the cooker and a second for the hob. each conduit carries 2 x 6 mm2 + 4 mm2 earth. Apologies to all.

Max

 

[Sintra]

All clear now lol.

 

[ipf]

Max if your using plastic pipe you can buy 2 types of elbows! Buy the larger type. it's a bigger and longer bend but its not as harsh on the bend as the smaller one and makes life a lot easier.

One's an elbow, the other a bend.........I believe!

 

[GLENNSPARK]

Lol@ the lube technique fairy does the trick every time. U will get 10mm if you use fairy lol jokes

washin up liquid eh?.....jesus wept...don`t you dare!!
to the O/P.....go and get some 77........

 

[ipf]

washin up liquid eh?.....jesus wept...don`t you dare!!
to the O/P.....go and get some 77........

Aye, too right.

 

[vjsmarwick]

personally i would have run one 20mm and 5 x 6mm should go through with swept bends you can share the earth and t box to first isolator then angle box up to second isolator i dont see a problem i am positive you can get all 5 x 6 mm in one 20mm conduit unless you are useing double insulated but there is no reason to if its in conduit

 

[Engineer54]

personally i would have run one 20mm and 5 x 6mm should go through with swept bends you can share the earth and t box to first isolator then angle box up to second isolator i dont see a problem i am positive you can get all 5 x 6 mm in one 20mm conduit unless you are useing double insulated but there is no reason to if its in conduit

I take it then, that you have never heard of maximum conduit fill?? Your suggestion would contravene just about every rule in the book!! lol!!

 

[i=p/u]

osg il sell you mine as i know it inside out , pfffft

 

[GLENNSPARK]

I take it then, that you have never heard of maximum conduit fill?? Your suggestion would contravene just about every rule in the book!! lol!!

well ive seen em with that many cables in em eng....its a wonder how they ever managed to get em all in there at all...

heres a prime example of something i came across a bit back at a factory i was doin some work on....lol...

 

[i=p/u]

was in firestation this week too and had to get cable from light switch to relay's and it was packed and i struggled to get a single brown through... and wasnt even in a position to drill new hole, the way pannel was designed and set into wall.... old sparks , who needs them

 

[Engineer54]

well ive seen em with that many cables in em eng....its a wonder how they ever managed to get em all in there at all...

heres a prime example of something i came across a bit back at a factory i was doin some work on....lol...

View attachment 16205

That doesn't even look like trunking to me, more like structual steelwork??

Needless to say, that amount of fill through a male bush, is just not acceptable!! CODE 1++!! lol!!

 

[telectrix]

ahhh, go on. sure i could get a couple more in there with a bit of lard.

 

[GLENNSPARK]

That doesn't even look like trunking to me, more like structual steelwork??

Needless to say, that amount of fill through a male bush, is just not acceptable!! CODE 1++!! lol!!

its old trunkin eng.....with all the lids of ov it (side mounted)........i found it to be overpopulated......together with neutrals entering metal enclosures on their own.....and other nastys like that.....

 

[i=p/u]

did you touch the hot headed eddy cuurents

 

[vjsmarwick]

I take it then, that you have never heard of maximum conduit fill?? Your suggestion would contravene just about every rule in the book!! lol!!

as you seem to be quite the expert can you tell me the maximum % fill in a conduit and then also tell me what the % fill will be with 5 x 6mm singles in it ? my guess is that it does not break any rules but not having tried it i dont know if it breaks the rules or not so i better just ask the expert !!

 

[Guest55]

interesting user name maximus , are you related to *biggus dickus by chance ?

snigger ;-)

*small monty python joke

 

[Sintra]

as you seem to be quite the expert can you tell me the maximum % fill in a conduit and then also tell me what the % fill will be with 5 x 6mm singles in it ? my guess is that it does not break any rules but not having tried it i dont know if it breaks the rules or not so i better just ask the expert !!

Why don't you work it out for yourself and prove yourself wrong.

 

[richy3333]

washin up liquid eh?.....jesus wept...don`t you dare!!
to the O/P.....go and get some 77........

Yellow 77, smear it on mu knob daily, who needs KY

 

[i=p/u]

they say the older the dryer, try a woman not a granny richy3333

 

[vjsmarwick]

Ok as I am in temp accommodation at the moment and don't have access to my bible I have been at my mates and trying to figure this out but the more we look at it the more confused we are becoming, for a 3 meter length the correction factor for 6mm is 88 but over 3 meter it drops to 58 i would have thought this would have been the other way around but there you go never mind that but if the op could have kept the run between his boxes to 3m instead of 4 then he could in fact run all 5 conductors needed in a 20mm conduit and not break a single rule but the extra meter makes it not work but its been a nice little refresher for me thanks guys but only conduit I use these days is to sleeve an outside light cable and I am sure in the multitude of regs changes since I needed to know they have changed this the same as everything else so I stand corrected sorry for doubting anyone but it was all over a meter

 

[PEG]

"that amount of fill through a male bush is just not acceptable..." I'm guessing your not an Elton John fan , eng...

 

[Engineer54]

Ok as I am in temp accommodation at the moment and don't have access to my bible I have been at my mates and trying to figure this out but the more we look at it the more confused we are becoming, for a 3 meter length the correction factor for 6mm is 88 but over 3 meter it drops to 58 i would have thought this would have been the other way around but there you go never mind that but if the op could have kept the run between his boxes to 3m instead of 4 then he could in fact run all 5 conductors needed in a 20mm conduit and not break a single rule but the extra meter makes it not work but its been a nice little refresher for me thanks guys but only conduit I use these days is to sleeve an outside light cable and I am sure in the multitude of regs changes since I needed to know they have changed this the same as everything else so I stand corrected sorry for doubting anyone but it was all over a meter

I can't check with anything to hand, but i'm pretty sure your wrong, maybe your relying on straight runs i would imagine here. Now try working it out with a single bend, as the OP has stipulated. I think you'll find a big difference in the outcome!! And that's apart from actually getting the cables pulled in to a 20mm conduit!!

 

[ipf]

And, with these short straight lengths of 20mm conduit, imagine removing and reinserting at every bend, elbow or even conduit box......could be quite difficult.

 

[GLENNSPARK]

they say the older the dryer, try a woman not a granny richy3333

lol!!...

 

[grantr37]

you can get bends and inspection elbows at screwfix, would use metal conduit myself with singles and use plastic just for telecom/data etc but that's just me maybe....

 

[Engineer54]

you can get bends and inspection elbows at screwfix, would use metal conduit myself with singles and use plastic just for telecom/data etc but that's just me maybe....

Using inspection elbows pulling in 5 6mm singles and you can guarantee scuffing insulation off the cables!! Inspection elbows and Tee's haven't been allowed on any major specified project installation since the 80's, these things can rip insulation to shreds. They should have been pulled/discontinued completely in my opinion... Inexperienced electricians that can't fabricate a decent conduit system tend to like them, ...though why they don't use Tee conduit boxes or angle boxes i don't know!! lol!!

 

[rmdes]

I've done it so it is possible gonna need two of you to feed and pull lots of cable lube and lots of swearing. (don't use washing up liquid it damages the cable). It's unfortunately a long process of pulling through a short length then lube and pull and lube, but doable.

Good luck

 

[i=p/u]

I had to tap off trunking one day in steel conduit and instead of bending like a master i used boxes to get to desired place, i can do 90 bends and thread it only lol the rest always ends up wrong.... But sure someday il jump on a job where there is loads of piping and get chance to practice .

Was considering buying pipe myself but havent yet.

 

[i=p/u]

Il say it again 5x6mm cables aint right in a conduit never mind with bends.

 

[rmdes]

Sorry must of read it wrong i just thought you were pulling 3x 6mm

5x 6mm not gonna happen in a 20mm conduit,
The capacity for heat etc and bends no chance

 

[Engineer54]

I've done it so it is possible gonna need two of you to feed and pull lots of cable lube and lots of swearing. (don't use washing up liquid it damages the cable). It's unfortunately a long process of pulling through a short length then lube and pull and lube, but doable.

Good luck

You've done it have you, ...5 X 6mm in 20mm around bends?? Stretch any of the cables pulling them in did you??

Sorry must of read it wrong i just thought you were pulling 3x 6mm

5x 6mm not gonna happen in a 20mm conduit,
The capacity for heat etc and bends no chance

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EDIT.... That's more like it!! Must have crossed on posting times lol!!