J

John Barsby

Hi guys,
I'm looking to run a single phase 60 amp supply 250 meters away with 3 core SWA and run a separate earth conductor.
Both to be in ducting underground what size cable should I use ?
 
do your cable calcs. CCC and volt drop. that will tell you what size of cable. TBH< if you can't be bothered or do not have the knowledge, then get in someone who can.
 
As above mate. Give us your calcs and your reasoning behind them and we will tell you if its ok. We like to teach people rather than just give info out.
 
Is this collage or real life job?

Looking through this guy's info it's not for college, he runs his own business. But you are right, it is a college question. It's either pure laziness or a shameful lack of knowledge for a professional electrician.
 
If the cable's 3 core, why are you proposing to run a separate earth conductor?

Thats what I was thinking... He doesnt give us enough info so its hard to help.
 
From what information he as given I am don't understand why he wants to run a separate CPC ?
The math is fairly basic to size the cable, I thought this was a electricians forum.
 
maybe he's considering 6mm and wants a 10mm for bonding to PME????? as he seems to have done a runner, we might never know.
 
From what information he as given I am don't understand why he wants to run a separate CPC ?
The math is fairly basic to size the cable, I thought this was a electricians forum.

haha. class...
The OP will most probably not get back to us, so it doesn't really matter...
 
I've done my calcs before I posted but as I'm not used to doing supply runs of this length I thought I'd just throw it out there see what people that had more experience in these type of installs thought. I'm sure I'm not the only one associated with these forums that is not an expert at every aspect of electrical.

Thanks for some of the more constructive relpy's but I'll refrain from posting next time. sjhall - real life m8 not internet!
 
Tell us what your calcs are and then we will anwer your question.
Why the separate earth conductor?
Are there any other power cables in this ducting?
 
top of my head, tin hat on, 95mm is a starting point. please discuss. i've had beer so might be way out.
 
top of my head, tin hat on, 95mm is a starting point. please discuss. i've had beer so might be way out.

Bit big... maybe 2 25mm cables in parellel. :) :) Will also add a link to a thread on where Eng54 and I discussing if grouping factors should be added..... :)
 
I've done my calcs before I posted but as I'm not used to doing supply runs of this length I thought I'd just throw it out there see what people that had more experience in these type of installs thought. I'm sure I'm not the only one associated with these forums that is not an expert at every aspect of electrical.

Thanks for some of the more constructive relpy's but I'll refrain from posting next time. sjhall - real life m8 not internet!

If you had posted your calcs up with your proposed size you would have got more help. Your original post came across as "Do this for me lads". You still have not posted up your workings.

Everyone is not an expert on everything, but this is college stuff mate and fully explained in the regs.

If you want to spit your dummy fine, but the forum is very helpful if you approach people with all the information you are armed with, and a proper question. By the way you really need to sort out your atrocious misuse of the apostrophe in this post and on your website.
 
Please tell me that someone else has to google the meaning of 'atrocious' .... or am I having a thick day...
 
atrocious.. latin.. brother of atricia.. they went to sea in a pea green boat.
 
If you had posted your calcs up with your proposed size you would have got more help. Your original post came across as "Do this for me lads". You still have not posted up your workings.

Everyone is not an expert on everything, but this is college stuff mate and fully explained in the regs.

If you want to spit your dummy fine, but the forum is very helpful if you approach people with all the information you are armed with, and a proper question. By the way you really need to sort out your atrocious misuse of the apostrophe in this post and on your website.

Boom

Bang

Kablammo!

What a reply :D
 
I would hazard a guess that the voltage drop is going to be the deciding factor over the current rating.
And I'm pretty sure you will find the armouring will be more than big enough to be the CPC so could cut costs by going down to 2core.
 
I've done my calcs before I posted but as I'm not used to doing supply runs of this length I thought I'd just throw it out there see what people that had more experience in these type of installs thought. I'm sure I'm not the only one associated with these forums that is not an expert at every aspect of electrical.

Thanks for some of the more constructive relpy's but I'll refrain from posting next time. sjhall - real life m8 not internet!

For some reason you seem reluctant to post your calcs up which only creates suspicion of your ability and this obviously puts your back up. Cable calcs don't fall anywhere near expert level IMO and probably don't for many others on here so your own comments only reinforce your ability or lack of it. If you are offended by any of the negative comments then the choice is yours post up your calcs so a proper constructive discussion can take place or don't and accept the criticism
 
I would hazard a guess that the voltage drop is going to be the deciding factor over the current rating.
And I'm pretty sure you will find the armouring will be more than big enough to be the CPC so could cut costs by going down to 2core.

Be careful here... at 250+ metres, the armouring may not be suitable to be used as the CPC. only calculations will confirm compliance or otherwise...
 
He's had enough stick for the minute so lets help him halfway.

1: Step one calculate design current.

2: Step Two Calculate tabulated current carrying capacity of the cable.

3: Calculate Voltage drop

4: Calculate Loop impedance

5: Calculate Protective conductor size

Job Done
 
He's had enough stick for the minute so lets help him halfway.

1: Step one calculate design current.

2: Step Two Calculate tabulated current carrying capacity of the cable.

3: Calculate Voltage drop

4: Calculate Loop impedance

5: Calculate Protective conductor size

Job Done

He claims to have done the calcs or don't you believe him like everyone else who has posted
 
just because im bored ive worked it out for you.

A 60amp design current with 80amp fuse and 250 meter run you would be looking at 120mm swa 2core

A 70mm earth would only be ok if zs is less than <0.27.

If you used a 120mm earth (eg 3core swa) than a zs >0.30

If you could get away with a 60ammp fuse then a 70mm earth is ok for zs >0.43 and the 120mm earth is ok >0.46
 
I'd be seriously looking at a parallel cable supply, it'll probably be cheaper too!! ...And i'd be looking at providing 3 core SWA cables rather than 2 core as well...
And NO, there will be no grouping factors to consider....
 
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SWA Cable Size
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John Barsby,
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Engineer54,
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