We are currently doing a job which requires us to upgrade an existing 1200 amp service to a 2000.There are existing 4 inch pipes ( 4 ) with parrallel 350 conductors. We planned to add 2 more 4 inch conduits and parrallel 500 conductors, to meet our 2000 amp needs. Does anyone have a better route for example adding more conduits for more 350 conductors instead of 500 mcm conductors. The 350 megged out fine and aare only 4 months old. Please give advice. Your help is greatly appreciated.
2000 amp SERVICE
- Thread starter butch
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
Re: 2000 amp SERVICE
Butch,
Is the grounded conductor a current carrying conductor in this service? It is a current carrying conductor only if a majority of the load in nonlinear. If the load is nonlinear, the 4 sets of 350s are only good for 1120 amps, not 1200.
If the grounded conductor is not a current carrying conductor, 10 350kcmil will fit in a 4" conduit. The 90?C ampacity (for derating) is 350 amps. You could install 8 350's in each raceway with a total ampacity of the circuit of 2240 amps. If the neutral of the service is a current carrying conductor, then the ampacity of the 4 conduits each with 8 350's would be 1960 amps. You are not permitted to round up, but if there is more than one service overcurrent protective device and if the calculated load is 1960 amps or less you could still use this set up. If the calculated load is above 1960 amps or if there is only one service OCPD rated at 2000 amps, then you could replace the 350 with 2 sets of 400 kcmil in each of the 4 conduits. This would give you an circuit ampacity, assuming a current carrying grounded conductor, of 2128 amps.
It sounds like you want to install the new 500s in parallel with the existing 350s. That would be a violation of 310.4. All of the conductors in parallel must be of the same size and type.
Don
Butch,
Is the grounded conductor a current carrying conductor in this service? It is a current carrying conductor only if a majority of the load in nonlinear. If the load is nonlinear, the 4 sets of 350s are only good for 1120 amps, not 1200.
If the grounded conductor is not a current carrying conductor, 10 350kcmil will fit in a 4" conduit. The 90?C ampacity (for derating) is 350 amps. You could install 8 350's in each raceway with a total ampacity of the circuit of 2240 amps. If the neutral of the service is a current carrying conductor, then the ampacity of the 4 conduits each with 8 350's would be 1960 amps. You are not permitted to round up, but if there is more than one service overcurrent protective device and if the calculated load is 1960 amps or less you could still use this set up. If the calculated load is above 1960 amps or if there is only one service OCPD rated at 2000 amps, then you could replace the 350 with 2 sets of 400 kcmil in each of the 4 conduits. This would give you an circuit ampacity, assuming a current carrying grounded conductor, of 2128 amps.
It sounds like you want to install the new 500s in parallel with the existing 350s. That would be a violation of 310.4. All of the conductors in parallel must be of the same size and type.
Don
- Location
- Massachusetts
Re: 2000 amp SERVICE
Don thats what it sounded like to me too, adding 500s to the 350s
This is a double post
The same question
Don thats what it sounded like to me too, adding 500s to the 350s
This is a double post
The same question
Re: 2000 amp SERVICE
Thanks for all the info but my intention was to pull out the 350 s from 4 4" conduits then add 2 more 4 inch pipes and run 6 parrallel runs of 500. But if I can run a 7th pipe and use only 350 conductors it seems to be more ecomonical and save a little money. the existing coductors megged out very good. Thanks again it sure helps with this forum to get more professional advice.
Thanks for all the info but my intention was to pull out the 350 s from 4 4" conduits then add 2 more 4 inch pipes and run 6 parrallel runs of 500. But if I can run a 7th pipe and use only 350 conductors it seems to be more ecomonical and save a little money. the existing coductors megged out very good. Thanks again it sure helps with this forum to get more professional advice.
- Location
- Illinois
- Occupation
- retired electrician
Re: 2000 amp SERVICE
Butch,
How long is this conduit run? Is there a single main overcurrent protective device?
Don
Butch,
How long is this conduit run? Is there a single main overcurrent protective device?
Don
masterinbama
Senior Member
- Location
- Huntsville Alabama
Re: 2000 amp SERVICE
if the terminals allow why not go with 1000mcm using the existing conduits
if the terminals allow why not go with 1000mcm using the existing conduits
- Location
- Massachusetts
Re: 2000 amp SERVICE
At our shop we have any tool we could want hydraulic wire benders and cutters, excellent pulling gear, but 600kcmil is the largest we will normally install.
It works much easier than 750kcmil and I can only guess 1000kcmil, that would be my reason, this guy wanted to make use of the 350s.
Does anyone have experience with 1000kcmil,
what is it like to work with?
I have not installed 1000kcmil I have scraped it and it seemed like it would be tough to use.
At our shop we have any tool we could want hydraulic wire benders and cutters, excellent pulling gear, but 600kcmil is the largest we will normally install.
It works much easier than 750kcmil and I can only guess 1000kcmil, that would be my reason, this guy wanted to make use of the 350s.
Does anyone have experience with 1000kcmil,
what is it like to work with?
- Location
- Massachusetts
Re: 2000 amp SERVICE
That's what I figured, the stuff I scrapped came out of a 12" x 12" trough facing up, so it had been laid in also.
It was cloth covered and was a bear to work with.
That's what I figured, the stuff I scrapped came out of a 12" x 12" trough facing up, so it had been laid in also.
It was cloth covered and was a bear to work with.
- Location
- Illinois
- Occupation
- retired electrician
Re: 2000 amp SERVICE
Look at the large pentaly in copper costs that you pay when using very large condctors. 1000kcmil has a 75?C ampacity of 545 amps, 300 kcmil has an ampacity of 285 amps. Parallel 300s have a higher rated amapcity, but use only 60% of the copper as a single 1000kcmil. Yes, two sets of parallel conducotors would require derating, but even assuming that the grounded conductor is a current carrying conductor and using the 70% adjustment factor, parallel 400s would have more ampacity than the 1000kcmil, use only 80% of the copper and be much easier to work with.
[ March 24, 2003, 03:11 PM: Message edited by: don_resqcapt19 ]
Look at the large pentaly in copper costs that you pay when using very large condctors. 1000kcmil has a 75?C ampacity of 545 amps, 300 kcmil has an ampacity of 285 amps. Parallel 300s have a higher rated amapcity, but use only 60% of the copper as a single 1000kcmil. Yes, two sets of parallel conducotors would require derating, but even assuming that the grounded conductor is a current carrying conductor and using the 70% adjustment factor, parallel 400s would have more ampacity than the 1000kcmil, use only 80% of the copper and be much easier to work with.
[ March 24, 2003, 03:11 PM: Message edited by: don_resqcapt19 ]
masterinbama
Senior Member
- Location
- Huntsville Alabama
Re: 2000 amp SERVICE
Sorry guys I was assuming that everyone had to follow the same rules. Our local utility will only allow 4 conductors per raceway on a service so the paralell conductors in 1 conduit just didn't seem right to me at first
Sorry guys I was assuming that everyone had to follow the same rules. Our local utility will only allow 4 conductors per raceway on a service so the paralell conductors in 1 conduit just didn't seem right to me at first
hbendillo
Senior Member
- Location
- South carolina
Re: 2000 amp SERVICE
One thing to keep in mind is to make sure you specify your switchboard with lugs to match your wiring. If 8-350 MCM per conduit were used I doubt that stadard lugs arrangements would accomodate them.
One thing to keep in mind is to make sure you specify your switchboard with lugs to match your wiring. If 8-350 MCM per conduit were used I doubt that stadard lugs arrangements would accomodate them.
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