wireguy8169
Senior Member
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- Southern Maine
Is it permissable to tap parallel conductors under any of the tap rules(Found nothing either way)? And if so would you also parallel the tap conductors so as not to overload any one tapped conductor?
Tapped Conductors
- Thread starter wireguy8169
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- Chapel Hill, NC
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- Retired Electrical Contractor
As long as you tap each parallel conductor of the phase then I don't see why that should be an issue.
wireguy8169
Senior Member
- Location
- Southern Maine
thanks
thanks
that is what I thought but did not find anything so figured ask and find out. When you figure out the conductor size it can not be less than 1/3 the ocpd size per 240.21 (B) now say I figure out the tap condutor size and it fits all requirements, when I parallel it I am thinking each individual tap wire will more than likely be less than the minimum 1/3 the size of the OCPD. Or in this instance would the tap conductors total ampacity or individual ampacity be taken? Hope this makes sense
thanks
thanks
that is what I thought but did not find anything so figured ask and find out. When you figure out the conductor size it can not be less than 1/3 the ocpd size per 240.21 (B) now say I figure out the tap condutor size and it fits all requirements, when I parallel it I am thinking each individual tap wire will more than likely be less than the minimum 1/3 the size of the OCPD. Or in this instance would the tap conductors total ampacity or individual ampacity be taken? Hope this makes sense
thanks
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One of the most used methods of tapping parallel conductors is a "polaris" type connector.
http://www.polarisconnectors.com/black.html
When discussed here, the most common Code referecne is 310.4, with the
thought that if you do not tap all conductors equally you are not maintaining the same characistics.
http://www.polarisconnectors.com/black.html
When discussed here, the most common Code referecne is 310.4, with the
thought that if you do not tap all conductors equally you are not maintaining the same characistics.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Good question but IMO I would say that the tap is related to the parallel not the individual wire. Obviously the parallel wires individually are not equal to the OCPD but paralleled they are sufficient.
So, I would say that if the OCPD was 900 amps then you could could use any wire sizes over 1/0 that would equal 300 amps. Thus parallel 1/0 copper wire would work assuming 75C.
wireguy8169
Senior Member
- Location
- Southern Maine
Same Characteristic
Same Characteristic
Yeah Augie and that is where the question came up. You would have to tap onto each conductor. So if your tapping say a parallel 500x3 run with an 800amp OCPD you would need at least 1/3 of the 800amps which is 264amps which you would need 300's now if you parallel you could do #3 X3 conductors which each are good for 100amps which is below the rule for the tap conductors (1/3 of OCPD) so can this be done or would you have to tap the 500's with 3 300's which most cases would be very cost prohibitive. Hope I explained it well enough to get an answer, thanks again
Same Characteristic
Yeah Augie and that is where the question came up. You would have to tap onto each conductor. So if your tapping say a parallel 500x3 run with an 800amp OCPD you would need at least 1/3 of the 800amps which is 264amps which you would need 300's now if you parallel you could do #3 X3 conductors which each are good for 100amps which is below the rule for the tap conductors (1/3 of OCPD) so can this be done or would you have to tap the 500's with 3 300's which most cases would be very cost prohibitive. Hope I explained it well enough to get an answer, thanks again
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
You cannot tape with #3 if you are paralleling the wires.
See if I understand your question.
Assuming a run with each phase consisting of two 500 kcmil conductors and protected by an 800 amp OCP device.
You wish to tap this and, for discusssions sake, you are terminting in a 200 amp OCP device with 15 ft of tap conductor.
A "polaris" tap is installed with both 500 kcmils entering and leaving.
240.21(C) requires the tap condcutor ampacity to be 1/3 of the 800 amp
(267 amps). So your tap would be a 300 kcmil.
Question being, could you use (3) #3 conductors for the tap.
Is that correct ?
My first answer would mirror Dennis' and be that, the taps could not be smaller than 1/0.
On reflection, an argument might made that the tap could not be less than 300 since even if you parelleled 1/0s the "tap conductor" ampacity would be less than 267 (each individual)
Assuming a run with each phase consisting of two 500 kcmil conductors and protected by an 800 amp OCP device.
You wish to tap this and, for discusssions sake, you are terminting in a 200 amp OCP device with 15 ft of tap conductor.
A "polaris" tap is installed with both 500 kcmils entering and leaving.
240.21(C) requires the tap condcutor ampacity to be 1/3 of the 800 amp
(267 amps). So your tap would be a 300 kcmil.
Question being, could you use (3) #3 conductors for the tap.
Is that correct ?
My first answer would mirror Dennis' and be that, the taps could not be smaller than 1/0.
On reflection, an argument might made that the tap could not be less than 300 since even if you parelleled 1/0s the "tap conductor" ampacity would be less than 267 (each individual)
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wireguy8169
Senior Member
- Location
- Southern Maine
Bascially
Bascially
Yeah, I know because of the tap rules that the conductors needs to be at least 1/3 the ampacity of the OCPD which in this case is 800amps, I am trying to figure out the minimum size tap conductors I can use, I have already come up with 300kcm first because 267amps is the 1/3 of 800amps and if I go lower then the conductors would not meet the requirements any longer. I am just making sure there is something I am not missing but have not found anything. So I will stick with my answer. Thanks for all the input
Bascially
Yeah, I know because of the tap rules that the conductors needs to be at least 1/3 the ampacity of the OCPD which in this case is 800amps, I am trying to figure out the minimum size tap conductors I can use, I have already come up with 300kcm first because 267amps is the 1/3 of 800amps and if I go lower then the conductors would not meet the requirements any longer. I am just making sure there is something I am not missing but have not found anything. So I will stick with my answer. Thanks for all the input
wireguy8169
Senior Member
- Location
- Southern Maine
My mistake
My mistake
Sorry, been doing so much in this book my head is spinning. This is the 10' tap rule OCPD ampacity on line side is not to exceed 10x's the tap conducto ampacity, I dont think I was specific enough. Again, sorry been awhile since had to do the book work. Appreciate all the input So, can go with 1/0, being that its the smallest conductor allowed. Break time
My mistake
Sorry, been doing so much in this book my head is spinning. This is the 10' tap rule OCPD ampacity on line side is not to exceed 10x's the tap conducto ampacity, I dont think I was specific enough. Again, sorry been awhile since had to do the book work. Appreciate all the input So, can go with 1/0, being that its the smallest conductor allowed. Break time
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- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
I disagree. I don't think you need to look at the tap conductor without seeing it as parallel. 1/0 is good for 150 amps so IMO, 2- 1/0 would be good for 300 amps. The single 1/0 does not have to be 1/3 of the OCPD. That would make no sense.
I guess it depends on if you use one wire as a tap or are you paralleling the tap. I was assuming 4- 1/0 conductors tied to the parallel main conductors- 1 from each conductor.
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