SER cable amapcity

[hhsting]

I have multifamily dwelling. The SER cable is used indoor to rout between main electrical room meter stack switchboard basement into each dwelling unit panelboard.

The meter stack has 125A breaker and SER cable used is #1 awg copper.

According to NEC 2017 Articles 334.80 and 338.10(B)(4)(a) should not size be #1/0 awg copper or should it be #1 awg copper?

 

[LarryFine]

Depends on the calculated load.

 

[hhsting]

Depends on the calculated load.

How? If load is xxA less than 125a then how can breaker sized 125A even protect the ser cable

 

[LarryFine]

The same way we can protect 4-0 al with 200a breakers.

 

[electrofelon]

Isn't #1 CU good for 130 even without the dwelling unit allowance? Am I missing something?

 

[hhsting]

The same way we can protect 4-0 al with 200a breakers.

Post #1 are not service conductors. Post #1 is feeder fed from 125A breaker meter stacks to individual dwelling units indoor. All equipment conductors are indoor. It is one building apartment complex.

Demand loads have nothing to do with this.


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[don_resqcapt19]

I have multifamily dwelling. The SER cable is used indoor to rout between main electrical room meter stack switchboard basement into each dwelling unit panelboard.

The meter stack has 125A breaker and SER cable used is #1 awg copper.

According to NEC 2017 Articles 334.80 and 338.10(B)(4)(a) should not size be #1/0 awg copper or should it be #1 awg copper?

334.80 does not apply.

Interior Installations. In addition to the provisions of this article, Type SE service-entrance cable used for interior wiring shall comply with the installation requirements of Part II of Article 334, excluding 334.80.

 

[hhsting]

Isn't #1 CU good for 130 even without the dwelling unit allowance? Am I missing something?

Yes see NEC 2017 Article 334.80. See NEC 2017 Article 338.10(B)(4)(a)

 

[hhsting]

334.80 does not apply.

Oh i see


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[don_resqcapt19]

Post #1 are not service conductors. Post #1 is feeder fed from 125A breaker meter stacks to individual dwelling units indoor. All equipment conductors are indoor. It is one building apartment complex.

Demand loads have nothing to do with this.


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Actually they do...if the calculated load is 115 amps or less, you can install 2 AWG copper from a 125 amp breaker.

 

[hhsting]

Actually they do...if the calculated load is 115 amps or less, you can install 2 AWG copper from a 125 amp breaker.

Where it states that we can do for feeder in NEC 2017?

 

[roger]

Where it states that we can do for feeder in NEC 2017?

240.4(B)

 

[hhsting]

Actually they do...if the calculated load is 115 amps or less, you can install 2 AWG copper from a 125 amp breaker.

What if demand load is 90A and 125A breaker? Cant have #4?


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[infinity]

What if demand load is 90A and 125A breaker? Cant have #4?

No. #4 AWG is 85 amps at 75° C. Cannot use that with a 90 amps calculated load.

 

[don_resqcapt19]

What if demand load is 90A and 125A breaker? Cant have #4?


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In addition to what Rob said in post 14, the rule in 240.4(B) would only let you use a 90 amp breaker for the 4AWG copper as 90 amps is the next larger standard OCPD for an 85 amp conductor