kitchen installation

[hawkeye23]

MY buddy ask me to help him with a new kitchen. He is a electrician with 3 years working in the residential end is planning on installing a 100amp sub panel with 3 wire # 4 cu.feed to it. This sub panel is for the new kitchen only with 2-20a countertop circuits 2-15a lighting circuit a dishwasher circuit and two circuits for two 8kw electric ovens and a circuit for the frig.

My concern here is we are installing too much in this sub panel and not sure how to correctly size this panel .
My main question is about the size of this sub panel is the load oversized for the sub panel ?
I can help with the installing the circuits but not too sure about the calculations. Thank you for any help you may give .
His oringnal permit did not include the 2 electric oven. His wife added this work later.

 

[curt swartz]

You need to do a load calculation per Article 220.

You need at least 4-wires for a 120/240 volt feeder unless you are running it in a metal raceway.

You can not use #4 for a 100 amp feeder.

 

[A/A Fuel GTX]

The 100A sub panel should be adequate but you would have to go with #3 CU for the feeder conductors and a #8 for the grounding conductor.

 

[Ponchik]

You need to do a load calculation per Article 220.

You need at least 4-wires for a 120/240 volt feeder unless you are running it in a metal raceway. He maybe talking about 4/3 copper NM cable. Otherwise you are correct, he needs 4 conductor.

You can not use #4 for a 100 amp feeder.

Why can't use #4 copper? I think he has based it on 310.15(b)(7)

 

[curt swartz]

Why can't use #4 copper? I think he has based it on 310.15(b)(7)

The reduced conductors in that table can only be used for service conductors or feeder conductors that carry the entire load of the dwelling.

That table has also never applied to Type NM cable. I'm amazed at how many times I see #4 NM cable installed for 100 amp feeders.

 

[A/A Fuel GTX]

Why can't use #4 copper? I think he has based it on 310.15(b)(7)

You can't use that table because the conductors are not carrying the full load of the service.

 

[ritelec]

The 100A sub panel should be adequate but you would have to go with #3 CU for the feeder conductors and a #8 for the grounding conductor.

3's or 2's ?

 

[Ponchik]

3's or 2's ?

3s based on the 75 degree table

 

[A/A Fuel GTX]

3's or 2's ?

3's if individual conductors in a conduit, 2's if SER

 

[Ponchik]

You need to do a load calculation per Article 220.

You need at least 4-wires for a 120/240 volt feeder unless you are running it in a metal raceway.

You can not use #4 for a 100 amp feeder.

Got it.

Thanks

 

[mgookin]

Can't that sub panel just be main lug?

 

[hawkeye23]

Thanks for the information we did not know the #4 is only used on the servcve. We do use the 75* c column ? Now because of cost we decided to use a #1 al cable.
It is a main lug only panel.

 

[A/A Fuel GTX]

Can't that sub panel just be main lug?

Absolutely...

 

[ritelec]

Please correct me if wrong.. 100 amp
single conductors in conduit thhn/thwn 75 degree = #3 cu
nm 60 degree = #2 cu

ser 75 degree = #1 al
ser 60 degree if running through insulation = 1/0 al

thank you

 

[Pharon]

kitchen installation

NEC 110.14(C)(1)(a)

 

[ritelec]

NEC 110.14(C)(1)(a)

Then #3 cu isn't permissible either..........nor the #1 al..

 

[Dennis Alwon]

Are you qualified to do this work otherwise I feel like we are doing a diy workaround.

Two 8kw ranges calculates to be 43 amps using col B in T 220.55

 

[edlee]

Thanks for the information we did not know the #4 is only used on the servcve. We do use the 75* c column ? Now because of cost we decided to use a #1 al cable.
It is a main lug only panel.

60 degree column. It needs 1/0 AL. Or you could install a 90a circuit and use something smaller.

 

[Pharon]

Then #3 cu isn't permissible either..........nor the #1 al..

You could use #3 Cu if the panel terminations are rated for 75 degrees C. Otherwise you need #2 Cu.

 

[kwired]

You could use #3 Cu if the panel terminations are rated for 75 degrees C. Otherwise you need #2 Cu.

Which they will be for new equipment, or even equipment about 30 years old likely will be.