240 sq.mm
- Thread starter jbolen
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- Chapel Hill, NC
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- Retired Electrical Contractor
Not sure of the exact ampacity of 250 sq.mm conductor but it is roughly equal to a 350 mcm conductor. 350 al is rated 250 amps at 75C and 280 @ 90C
500 mcm is rated 310 at 75C or 350 at 90C
500 mcm is rated 310 at 75C or 350 at 90C
mbrooke
Batteries Included
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- United States
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- Technician
Are you working with the NEC? I only ask because sqmm isnt listed in table 310.15.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Here is a table that shows that 250 sq. mm = 500 mcm cable
http://www.scribd.com/doc/35662243/...-With-Ampacity-of-Insulated-Conductors#scribd
http://www.scribd.com/doc/35662243/...-With-Ampacity-of-Insulated-Conductors#scribd
Depends on a number of factors. Single core, in free air, embedded in a wall...........
Anywhere from about 400A to 600A according to BS 7671.........
Wondering this myself...???
AFAIK, there are no mm²-sized conductors which are a type recognized by the NEC.
petersonra
Senior Member
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- Northern illinois
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- engineer
that would be the real issue.
I think there are some these days, but I can't recall the last time I ran across them, and I seem to recall only seeing them in smaller sizes.
epimetheus
Member
240mm^2 = 474kcmil per this link:
https://www.anixter.com/content/dam/Anixter/Guide/7H0011X0_W&C_Tech_Handbook_Sec_17.pdf
https://www.anixter.com/content/dam/Anixter/Guide/7H0011X0_W&C_Tech_Handbook_Sec_17.pdf
petersonra
Senior Member
- Location
- Northern illinois
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- engineer
it is not all that hard to convert from mm^2 to kcm. They are just two different units of cross sectional area.
However, most conductors spec'd in mm^2 are not of a type that the NEC recognizes, as has been mentioned in previous posts, so even if you can come to some kind of conclusion about its ampacity, if it is not a NEC recognized type of conductor insulation, you can't use it in a NEC installation.
However, most conductors spec'd in mm^2 are not of a type that the NEC recognizes, as has been mentioned in previous posts, so even if you can come to some kind of conclusion about its ampacity, if it is not a NEC recognized type of conductor insulation, you can't use it in a NEC installation.
- Location
- Illinois
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- retired electrician
I thought all of the larger DLO was in circular mils...just some non-standard ones like 262.6, 313.3 and 535.3 kcmil (there are others too). I just use the next smaller standard size for ampacities where I am using DLO. You do have to watch out for the manufacturer's ampacities for DLO...they are almost always based on 90° C in free air.
That was actually my point Don, up to 4/0 they are sized the same as AWG, after that the larger sizes are in circular mils. We do the same as you do when we do use it but I guess it could be questioned by someone.
Roger
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