Multiple questions???

[Benton]

Hi Guys,

If I have 12- #12current carrying conductors in a 2" pipe (multiwire 3 phase) do I need to consider derateing? I know that I am not close to my conduit fill, but I am concerned about ampacity.

Can 350 AWG be paralleled for an 800amp service?

Where online can I find GE product 3phase reasonably priced.

Thanks

 

[qcroanoke]

Hi Guys,

If I have 12- #12current carrying conductors in a 2" pipe (multiwire 3 phase) do I need to consider derateing? I know that I am not close to my conduit fill, but I am concerned about ampacity.

Can 350 AWG be paralleled for an 800amp service?

Where online can I find GE product 3phase reasonably priced.

Thanks

Yes.
Yes.
Not sure just keep looking.

 

[bob]

Hi Guys,

If I have 12- #12current carrying conductors in a 2" pipe (multiwire 3 phase) do I need to consider derateing? I know that I am not close to my conduit fill, but I am concerned about ampacity. Table 310.15B2a does not mention conduit size.

Can 350 AWG be paralleled for an 800amp service? 620 amps is a long way from 800 amps.

Where online can I find GE product 3phase reasonably priced.

Thanks

Thanks

 

[Benton]

I didn't run the conduit or pull the wires. Should I break up the circuits into runs of 12/4 because I will have to increase wire sizes with current scheme otherwise?

 

[charlie b]

Can 350 AWG be paralleled for an 800amp service?

No. If the calculated load is less than 620 amps, then you can use a pair of 350's. However, you have to protect the service with an OCPD no higher than 700 amps (i.e., the next standard size that is higher than 620).

 

[charlie b]

I didn't run the conduit or pull the wires. Should I break up the circuits into runs of 12/4 because I will have to increase wire sizes with current scheme otherwise?

Not so fast, if you please. I need clarification. If you are dealing with three circuits, each a MWBC consisting of three phase conductors and a neutral conductor, then you are not necessarily dealing with 12 current-carrying conductors. If there are no significant harmonic loads on these circuits, then you only have nine current-carrying conductors. In that case, a #12 THHN derates from 30 amps down to 21 amps. Therefore, you can still use a #12 with a 20 amp breaker. So you could put all 12 wires (plus the EGC) in the same conduit.