SWA Cable Size

[John Barsby]

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!

 

[Spoon]

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?

 

[telectrix]

top of my head, tin hat on, 95mm is a starting point. please discuss. i've had beer so might be way out.

 

[sjhall]

To be fair it is a super long run... What are you supplying? Have you done any calcs so far?

 

[Spoon]

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.....

 

[Andy78]

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.

 

[Spoon]

Please tell me that someone else has to google the meaning of 'atrocious' .... or am I having a thick day...

 

[telectrix]

atrocious.. latin.. brother of atricia.. they went to sea in a pea green boat.

 

[sparkymalarky]

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

 

[davesparks]

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.

 

[UNG]

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

 

[Engineer54]

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...

 

[george.nec]

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

 

[UNG]

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

 

[Jimmyb]

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