I have 4 parallel runs of 500MCM cable from existing sub to switchboard. Cable is protected with 1600A fused disconnect switch - 10 years ago. I need to remove this switchboard and install two new swb's each 800A. Does CODE allow me to splice 4 runs of 500MCM into (2) 2 runs of 600MCM and feed two swbd's? Code distances will be satisfied.
splicing of 500MCM
- Thread starter snjeza
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Re: splicing of 500MCM
I don't understand. Will there still be a 1600A fuse? Will all 4 sets of 500's still be tied together at both ends? Why would you splice 600's onto 500's? Do you mean 2 sets of 600's to each 800A swbd. What code distances are satisfied?
Sorry, but need more info. With what I am visualizing, the only way I see to do this is leave the 4 sets of 500's protected at their source with a 1500A fuse or breaker (1600 is too large for 4 sets of 500), terminate all 4 sets at a 1600A switchboard, tap 2 sets of 500's (or 600's) to each 800A panel, and provide 800A overcurrent protection at each panel.
Steve
I don't understand. Will there still be a 1600A fuse? Will all 4 sets of 500's still be tied together at both ends? Why would you splice 600's onto 500's? Do you mean 2 sets of 600's to each 800A swbd. What code distances are satisfied?
Sorry, but need more info. With what I am visualizing, the only way I see to do this is leave the 4 sets of 500's protected at their source with a 1500A fuse or breaker (1600 is too large for 4 sets of 500), terminate all 4 sets at a 1600A switchboard, tap 2 sets of 500's (or 600's) to each 800A panel, and provide 800A overcurrent protection at each panel.
Steve
Re: splicing of 500MCM
yes, you understood what I was doing.
Cables will be spliced all together at exist. swbd.
I have 1600A protection in existing sub and per 90C 500MCM is protected (one 500MCM = 430A).
New spliced cable will be for 75C so, 500MCM will not be protected. I planned to run 2 of 600MCM parallel runs for each switchboard and was not sure is that OK per code.
Was not sure is there a code issue with splicing 90C rated cable of 500MCM to 75C rated cable of 600MCM.
Ignore distances...., I'm mounting swbd's at diffrenet location and will have protection after taps.
Thanks for replay and say something if you see problems.
yes, you understood what I was doing.
Cables will be spliced all together at exist. swbd.
I have 1600A protection in existing sub and per 90C 500MCM is protected (one 500MCM = 430A).
New spliced cable will be for 75C so, 500MCM will not be protected. I planned to run 2 of 600MCM parallel runs for each switchboard and was not sure is that OK per code.
Was not sure is there a code issue with splicing 90C rated cable of 500MCM to 75C rated cable of 600MCM.
Ignore distances...., I'm mounting swbd's at diffrenet location and will have protection after taps.
Thanks for replay and say something if you see problems.
Re: splicing of 500MCM
Unless your 1600A panel has 90 degree rated terminals, you have to use the 75 degree rating for your existing 500KCM wires. That gives you 380 x 4 = 1520 Amps going to the first panel. Since its above 800A, you can't upsize the breaker to 1600A. So, it doesn't sound like the existing wires are large enough (which is what I think Bob is refering to).
If you tapped the 1600A panel with two sets of 500's for each 800A panel, that's 380 x 2 = 760 A per panel. You can upsize that breaker to 800A if the calculated load isn't more than 760A on each panel. So, I'm not sure you would need to go up to 600's.
Steve
Unless your 1600A panel has 90 degree rated terminals, you have to use the 75 degree rating for your existing 500KCM wires. That gives you 380 x 4 = 1520 Amps going to the first panel. Since its above 800A, you can't upsize the breaker to 1600A. So, it doesn't sound like the existing wires are large enough (which is what I think Bob is refering to).
If you tapped the 1600A panel with two sets of 500's for each 800A panel, that's 380 x 2 = 760 A per panel. You can upsize that breaker to 800A if the calculated load isn't more than 760A on each panel. So, I'm not sure you would need to go up to 600's.
Steve
Re: splicing of 500MCM
OK, I will try again.
I have existing 4 runs of 500MCM cables from existing substation 90C rated (sub and cables) going to 1600A switchboard. Now I'm removing switchboard and installing two new 800A switchboards 75C rated. I will splice 4 runs of 500MCM (90C rated) cables into 4 runs of 600MCM (75C rated) and feed those two 800A switchboards (each with 2 runs of 600MCM). Question is: Is there issue with code because of splicing 4 runs of 500MCM cables 90C rated to 4 runs of 600MCM cables 75C rated. Protection in existing substation will stay the same 1600A.
OK, I will try again.
I have existing 4 runs of 500MCM cables from existing substation 90C rated (sub and cables) going to 1600A switchboard. Now I'm removing switchboard and installing two new 800A switchboards 75C rated. I will splice 4 runs of 500MCM (90C rated) cables into 4 runs of 600MCM (75C rated) and feed those two 800A switchboards (each with 2 runs of 600MCM). Question is: Is there issue with code because of splicing 4 runs of 500MCM cables 90C rated to 4 runs of 600MCM cables 75C rated. Protection in existing substation will stay the same 1600A.
websparky
Senior Member
- Location
- Cleveland, Ohio
Re: splicing of 500MCM
Simply splicing larger wire to extend or change the size does not negate the fact that 500Kcmil conductors are rated at 380A when they are anywhere in the circuit that is terminated at one end with 75C connections. This is a very basic concept. To the best of my knowledge, there are NO terminations rated at 90C. The actual lug where the conductor terminates. This connection is THE rating of the circuit regardless of the conductor rating.
Simply splicing larger wire to extend or change the size does not negate the fact that 500Kcmil conductors are rated at 380A when they are anywhere in the circuit that is terminated at one end with 75C connections. This is a very basic concept. To the best of my knowledge, there are NO terminations rated at 90C. The actual lug where the conductor terminates. This connection is THE rating of the circuit regardless of the conductor rating.
- Location
- Illinois
- Occupation
- retired electrician
Re: splicing of 500MCM
Dave,
He says that he is comming out of a substation. If the connections at the sub are to exposed buss bars there is a very good chance that you can use the 90?C rating.
Don
Dave,
He says that he is comming out of a substation. If the connections at the sub are to exposed buss bars there is a very good chance that you can use the 90?C rating.
Don
Re: splicing of 500MCM
snjeza:
I'm not sure about splicing 75 deg. 600's onto 90 deg. 500's. I don't know of any code that prohibits that, but I also don't know of any code that allows it.
You said you are removing the 1600A switchboard. Will your existing 4 sets of 500's still be bussed together at both ends? You cannot feed 4 sets of wire from one breaker and have them terminate at separate panels. That doesn't fit the definition of parallel conductors.
Steve
snjeza:
I'm not sure about splicing 75 deg. 600's onto 90 deg. 500's. I don't know of any code that prohibits that, but I also don't know of any code that allows it.
You said you are removing the 1600A switchboard. Will your existing 4 sets of 500's still be bussed together at both ends? You cannot feed 4 sets of wire from one breaker and have them terminate at separate panels. That doesn't fit the definition of parallel conductors.
Steve
Re: splicing of 500MCM
sorry, I'm on the same page now should have read futher.
You can"t upsize your wire in the middle of a run
you'r wire will still be undersized from the taps back to the main
you have to replace the entire run with 600mcm even if it is coming from a sub station at 90c lugs the lugs at the panel is still 75.
Unless you could get poco to give you some of those 90c lugs
sorry, I'm on the same page now should have read futher.
You can"t upsize your wire in the middle of a run
you'r wire will still be undersized from the taps back to the main
you have to replace the entire run with 600mcm even if it is coming from a sub station at 90c lugs the lugs at the panel is still 75.
Unless you could get poco to give you some of those 90c lugs
- Location
- Illinois
- Occupation
- retired electrician
Re: splicing of 500MCM
ccha9219,
If the feed originates at a busbar and the terminations are suitable for 90?C there is no reason that you can't splice the 500kcmil to 600kcmil cables before you land on the load end that requires 75?C terminations.
Don
ccha9219,
If the feed originates at a busbar and the terminations are suitable for 90?C there is no reason that you can't splice the 500kcmil to 600kcmil cables before you land on the load end that requires 75?C terminations.
Don
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: splicing of 500MCM
Edit reference to 215.2. I need to start looking in the book before I post
[ March 25, 2004, 06:24 PM: Message edited by: ryan_618 ]
230.42 or 215.6 might not allow it, depending on the computed load.
Edit reference to 215.2. I need to start looking in the book before I post
[ March 25, 2004, 06:24 PM: Message edited by: ryan_618 ]
Re: splicing of 500MCM
I recently made an inquiry with my local distributor He has told me that any gear now being manufactured above 100 amps has 90c rated lugs. He also informed me that he got his info not only from the manufacturer, but Mr. Holt as well. can anyone confirm this???
I recently made an inquiry with my local distributor He has told me that any gear now being manufactured above 100 amps has 90c rated lugs. He also informed me that he got his info not only from the manufacturer, but Mr. Holt as well. can anyone confirm this???
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