Quick question, I have a 1325amp load @ 480v 3 phase about a 150feet from the breaker and was using a oneline wire sizing calculator and it told me I could use a 3c #400mcm and according to the NEC thats not right, can someone please tell me what size and how many per phase I would need. I am thinking 3 500mcm per phase..
1325 amp 480v load wire size
- Thread starter justahand
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ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: 1325 amp 480v load wire size
I would reccommend pulling 4 sets of 400.
Remember that 210.19, 215.2 and 230.42 all require your conductors to carry the load.
I would reccommend pulling 4 sets of 400.
Remember that 210.19, 215.2 and 230.42 all require your conductors to carry the load.
Re: 1325 amp 480v load wire size
If this is a feeder or service entrance, wouldn't the (4) sets of 400's have to be protected at 1200 amps??
And if the load is continuous, you might have to size the wire for 125% of the load.
It would be helpful if we knew a little bit about the load.
Steve
[ May 09, 2005, 09:18 AM: Message edited by: steve66 ]
If this is a feeder or service entrance, wouldn't the (4) sets of 400's have to be protected at 1200 amps??
And if the load is continuous, you might have to size the wire for 125% of the load.
It would be helpful if we knew a little bit about the load.
Steve
[ May 09, 2005, 09:18 AM: Message edited by: steve66 ]
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: 1325 amp 480v load wire size
I came up with (4sets)(335amps)=1340amps
I came up with (4sets)(335amps)=1340amps
john m. caloggero
Senior Member
Re: 1325 amp 480v load wire size
It appears that this is a feeder supplied from an OCD. If all conductors are installed in one raceway, it would require four 500 Kcmil, Cu. From the 90 deg column; 430A x 4 x .80 = 1375A. You are allowed to derate from the 90 deg column if you use 90 deg conductors. If the conductors are in 4 raceways, you can use 400 Kcmil, cu conductors.
It appears that this is a feeder supplied from an OCD. If all conductors are installed in one raceway, it would require four 500 Kcmil, Cu. From the 90 deg column; 430A x 4 x .80 = 1375A. You are allowed to derate from the 90 deg column if you use 90 deg conductors. If the conductors are in 4 raceways, you can use 400 Kcmil, cu conductors.
john m. caloggero
Senior Member
Re: 1325 amp 480v load wire size
Don't forget about the OCD supplying the conductors cannot be greater than 1375 for the exampe I provided.
Don't forget about the OCD supplying the conductors cannot be greater than 1375 for the exampe I provided.
Re: 1325 amp 480v load wire size
If the overcurrent device can't be over 1375 amps, the next standard size down is 1200 amps. Unless you can get a nonstandard device rated at 1375 amps, or unless you can use 240.4(G) (maybe its a motor load??), it seems like the wire might have to be upsized to the next standard breaker - 1600 amps.
That's 4 sets of 600's in separate conduits.
If the overcurrent device can't be over 1375 amps, the next standard size down is 1200 amps. Unless you can get a nonstandard device rated at 1375 amps, or unless you can use 240.4(G) (maybe its a motor load??), it seems like the wire might have to be upsized to the next standard breaker - 1600 amps.
That's 4 sets of 600's in separate conduits.
john m. caloggero
Senior Member
Re: 1325 amp 480v load wire size
Steve66: An adjustable trip breaker is allowed, provided there is restricted access to the adjusting means. See 240.6(C)
Steve66: An adjustable trip breaker is allowed, provided there is restricted access to the adjusting means. See 240.6(C)
james wuebker
Senior Member
- Location
- Iowa
Re: 1325 amp 480v load wire size
Don't forget about some voltage drop in this setup.
Jim
Don't forget about some voltage drop in this setup.
Jim
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: 1325 amp 480v load wire size
That isn't a code issue though
james wuebker
Senior Member
- Location
- Iowa
Re: 1325 amp 480v load wire size
ryan
It is a code issue.
Jim
ryan
It is a code issue.
Jim
james wuebker
Senior Member
- Location
- Iowa
Re: 1325 amp 480v load wire size
Ryan, I mean that voltage drop isn't in the code but if your running your voltage to low, lets say on motors your could be drawing more amps which then more amps on the wire. I know it probolay would be a problem here but I think of things at all angles.
Jim
Ryan, I mean that voltage drop isn't in the code but if your running your voltage to low, lets say on motors your could be drawing more amps which then more amps on the wire. I know it probolay would be a problem here but I think of things at all angles.
Jim
james wuebker
Senior Member
- Location
- Iowa
Re: 1325 amp 480v load wire size
kiloamp7
I was thinking that he said the LOAD was 1325 amps. Is this his limit. Is this going to be a running load for more than 3 hrs. or is this just a sub panel he's adding.
Jim
kiloamp7
I was thinking that he said the LOAD was 1325 amps. Is this his limit. Is this going to be a running load for more than 3 hrs. or is this just a sub panel he's adding.
Jim
Re: 1325 amp 480v load wire size
Not sure what you are saying, james w.- voltage drop is voltage drop.
If we are talking about voltage drop, continuous load really has nothing to do with it. Also doesn't matter to the conductors whether they are service, feeder, or branch.
Not sure what you are saying, james w.- voltage drop is voltage drop.
If we are talking about voltage drop, continuous load really has nothing to do with it. Also doesn't matter to the conductors whether they are service, feeder, or branch.
james wuebker
Senior Member
- Location
- Iowa
Re: 1325 amp 480v load wire size
OK kiloamp7, I will agree with you. I'll stop.
Thanks
Jim
OK kiloamp7, I will agree with you. I'll stop.
Thanks
Jim
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