Discuss Using SWA cables in parallel in the Industrial Electrician Talk area at ElectriciansForums.net

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Hi
A job that I'm currently looking at requires a 300A 3ph supply to a unit. The cable will be 100m long so the calc comes out at 240mm2. This cable is to be pulled down a duct, the main issue is it's weight and size will be a battle. I'm thinking of running two 95mm2 in parallel that would make this job possibly easier. What are everyone's thoughts?
 
Hi
A job that I'm currently looking at requires a 300A 3ph supply to a unit. The cable will be 100m long so the calc comes out at 240mm2. This cable is to be pulled down a duct, the main issue is it's weight and size will be a battle. I'm thinking of running two 95mm2 in parallel that would make this job possibly easier. What are everyone's thoughts?
If they where singles you where pulling in I'd say parallel is a good choice but 2 x 95mm can you get them down the duct?
Plus it's two glands to make off and terminate at each end.
Aluminium conductors maybe a better choice.
Or stick with the one cable.
240 mm at 70 degrees operating temp 3 phase is less than 300 amps tho ref method D only gives ambient temp at 20 degrees and that's with out a correction factor of 0.9 to bring it to 30 degree ambient temperature
 
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Parallel cables will have a reduced overall csa compared to one cable and are often used for large submains. If your calculations are okay it is the best option.
 
If they where singles you where pulling in I'd say parallel is a good choice but 2 x 95mm can you get them down the duct?
Plus it's two glands to make off and terminate at each end.
Aluminium conductors maybe a better choice.
Or stick with the one cable.
240 mm at 70 degrees operating temp 3 phase is less than 300 amps tho ref method D only gives ambient temp of 20 degrees and that's with out a correction factor of 0.9 to bring it to 30 degree ambient temperature
Two 95.0 better than pulling one 240.0.
 
240mm 3 or 4 core , 3 phase is only 280 amps then using the maximum operating temperature at 70 degrees without applying correction factors
 
The duct is 12" so quite large and is completely straight. I calc it with 0.8-pf, ambient temp 20 degrees and on a xlpe at 240mm2. Do you get a different answer?
 
The duct is 12" so quite large and is completely straight. I calc it with 0.8-pf, ambient temp 20 degrees and on a xlpe at 240mm2. Do you get a different answer?
Think you've used xlpe at 90 degrees operating temperature and not 70 degrees.
There is a note in the tables making you aware of connecting 90 degree to 70 degree accessories and switch gear.
You need to apply a 0.9 correction factor straight away If cable in a duct or buried as tables give ccc at 20 degrees and not 30 degrees reference method D
 
Ha you just have read my mind Ian! Yes I have done that! I the panel board it is connecting to is quite small so I was thinking the two 95mm2 would be easier to terminate. I was always under the impression that washing up liquid makes the pvc deteriorate?
 
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Ha you just have read my mind Ian! Yes I have done that! I the panel board it is connecting to is quite small so I was thinking the two 95mm2 would be easier to terminate. I was always under the impression that washing up liquid makes the pvc deteriorate?
well never poured it on cables so I don't know haha.
 
Dpes anyone know what factoring is applied for parallel supplies? I think the CSA normally works out less that with one cable
 
Have you tried sizing it with three cables. Another thought does the armour have to support main protective bonds upstream.
 

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