NEC 220.82 interpretation

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Tainted

Tainted

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New York
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Engineer (PE)
NEC 220.82 says we can only use it on a 3-wire service or feeder conductors with ampacity of 100amp or greater.

Can we use NEC 220.82 demand calculation to calculate feeders and overcurrent protection on a 3-phase 4-wire non service dwelling unit?
 
Tainted said:
NEC 220.82 says we can only use it on a 3-wire service or feeder conductors with ampacity of 100amp or greater.

Can we use NEC 220.82 demand calculation to calculate feeders and overcurrent protection on a 3-phase 4-wire non service dwelling unit?
Click to expand...

I am confused- you state that the code says only 3 wire service or feeder and you want to know if you can use 3phase 4 wire service for non-dwelling? The heading also states Dwelling Units..

I think you answered your own question... I would say "NO" you cannot.

220.82 Dwelling Unit.
(A) Feeder and Service Load. This section applies to a dwelling
unit having the total connected load served by a single
120/240-volt or 208Y/120-volt set of 3-wire service or feeder
conductors with an ampacity of 100 or greater. It shall be
permissible to calculate the feeder and service loads in accordance
with this section instead of the method specified in
Part III of this article.
Click to expand...
 
Dennis Alwon said:
I am confused- you state that the code says only 3 wire service or feeder and you want to know if you can use 3phase 4 wire service for non-dwelling? The heading also states Dwelling Units..

I think you answered your own question... I would say "NO" you cannot.
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The way I’m reading it is that you can use it for a 3-wire service but the apartment does not have a service conductors, it has a feeder so that’s why it says “or feeder conductors “
 
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Tainted said:
The way I’m reading it is that you can use it for a 3-wire service but the apartment does not have a service conductors, it has a feeder so that’s why it says “or feeder conductors “
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I agree but you were asking 3 phase and non dwelling. I agree that the equipment grounding conductor is not considered in the 3 wire setup for feeder
 
Dennis Alwon said:
I agree but you were asking 3 phase and non dwelling. I agree that the equipment grounding conductor is not considered in the 3 wire setup for feeder
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Ooooh, no let me clarify:

Can we use NEC 220.82 demand calculation to calculate feeders and overcurrent protection on a 3-phase 4-wire dwelling unit feeder. This apartment is 4-wire non-service. It is just fed from regular 4-wire feeders.
 
I see what's going on- I'm dense at times.... It's a good question but I believe you can use 220.82. Imo, this section could use some re-wording
 
Tainted said:
NEC 220.82 says we can only use it on a 3-wire service or feeder conductors with ampacity of 100amp or greater.

Can we use NEC 220.82 demand calculation to calculate feeders and overcurrent protection on a 3-phase 4-wire non service dwelling unit?
Click to expand...
If you're asking if the phrase "3-wire service or feeder" means "3-wire (service or feeder)" or means "(3-wire service) or feeder," then I would say the former is the standard meaning in English. The latter should be written as "feeder or 3-wire service" to avoid this ambiguity.

You have a 4-wire 3-phase feeder to a single dwelling unit? 220.84 for feeders/services for multiple dwelling units doesn't have the voltage system restriction of 220.82.

Cheers, Wayne
 
(2017NEC) 220.82 Dwelling Unit.
(A) Feeder and Service Load. This section applies to a dwelling
unit having the total connected load served by a single
120/240-volt (single phase) or 208Y/120-volt (3 phase) set of 3-wire service or feeder
conductors (neutral not counted into this see reference to 220.61 ) with an ampacity of 100 or greater. It shall be
permissible to calculate the feeder and service loads in accordance
with this section instead of the method specified in
Part III of this article. The calculated load shall be the result of
adding the loads from 220.82(B) and (C). Feeder and service entrance
conductors whose calculated load is determined by
this optional calculation shall be permitted to have the neutral
load determined by 220.61.

To me "feeder" as opposed to "service" would imply the required separation of N/G, and a total number of conductors even on single phase minimally 4 conductors. So if the wording limiting to 3 wire was literal counting the neutral, it could never be used in calculating "feeder" load.

IMO you could use this alternate method for 3 phase as long as all other required limitations are met.
 
AlexKLMN said:
Still confusing for me, Can we use NEC 220.82 for a 3-phase 4-wire dwelling unit feeder calculation?
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The text specifies a "120/240-volt or 208Y/120-volt set of 3-wire" supply. So a single dwelling unit with a 208Y/120V 4 wire supply can't use 220.82.

Now if you have 3 dwelling units on a 208Y/120V 4-wire supply, which is further broken out as a balanced set of (3) 208Y/120V 3-wire supplies, each to one of the dwelling units, then you can use 220.82 for each of the individual dwelling unit feeders. And I would argue that you can sum those results for the 208Y/120V 4-wire supply, although that is not uncontested. But then you could also use 220.84 for the 208Y/120V 4-wire supply, which is the more typical option.

Cheers, Wayne
 
AlexKLMN said:
But the text also specifies "... or feeder with an ampacity of 100 or greater ".
Click to expand...
The parsing is

"a single (120/240-volt or 208Y/120-volt) set of 3-wire (service or feeder conductors) with an ampacity of 100 or greater."

So for 220.82 to apply, it must be (a) 120/240V or 208Y/120 (b) 3-wire (c) service or feeder conductors and (d) with an ampacity of 100A or greater.

Cheers, Wayne
 
The problem is that there is no 'and ' but it's only 'or' 100 Amp
So, I read it as 120/240 3-wire or 208/120 or 208/120 3-wire OR 100 Amp which means for me if it is 100 Amp I can use any system.
Probably because English is not my native language:)
Thank You!
 
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