310.15b?

[truluckj]

When feeding a dwelling service via 120/208 1phase, can you use 310.15b?

 

[iwire]

Table 310.15(B)(6)?

No, the feeder to a garage must be sized per Table 310.16

 

[dana1028]

garage??

Table 310.15(B)(6) is limited to 12/240V 3-wire services.

 

[raider1]

When feeding a dwelling service via 120/208 1phase, can you use 310.15b?

No, as dana1028 pointed out Table 310.15(B)(6) only applys to 120/240 volt, 3 wire single phase systems.

Chris

 

[Dennis Alwon]

When feeding a dwelling service via 120/208 1phase, can you use 310.15b?

Is there such a service as 120/208 single phase ?

 

[iwire]

Yes, quite common in cities, well at least in my area.

 

[480sparky]

How did a garage get into the picture?

It's not mentioned in the OP.

 

[Dennis Alwon]

Yes, quite common in cities, well at least in my area.

Never have seen it. So why do you suppose T310.15(B)(6) only applies to 120/240 services? Any ideas other than that's what the code states? :smile:

 

[Dennis Alwon]

How did a garage get into the picture?

It's not mentioned in the OP.

Bob has inside info.

 

[donselectric]

208 in resi in mass ???? where?

 

[480sparky]

Bob has inside info.

The garage is inside?!?!?!

 

[iwire]

208 in resi in mass ???? where?

Boston for sure and I think Brookline and Cambridge as well. Not all of the city, just parts.

 

[Dennis Alwon]

The garage is inside?!?!?!

Sure if ir were outside it would be a carport.

 

[iwire]

How did a garage get into the picture?

It's not mentioned in the OP.

I don't know, I must have been seeing things.

 

[iwire]

From NStars service book

C. 120/280 volts, single phase, 3 wire, service
Normally available only in the Downtown Boston Network
District for connected loads not greater than 200 amperes.
This service may be available upon consultation with
NSTAR. Larger services must be three phase, 4 wire.

 

[iwire]

Never have seen it. So why do you suppose T310.15(B)(6) only applies to 120/240 services? Any ideas other than that's what the code states? :smile:

My guess is that with a 120/240 single phase feeder code wise you only have two current carrying conductors. With a 208/120 single phase feeders all 3 conductors are considered current carrying.

It's a total guess and may be wrong.

 

[truluckj]

Further info

Further info

We are feeding a multifamily apartment bldg 120/208 3ph. The single family units are being fed 120/208 1ph. Why can't you use 310.15(B)(6). How does the voltage affect the fact you are still feeding a single family dwelling.