3 three phase circuits cfrancka

[cfrancka]

Can you put 3 three phase circuits in the same raceway?

I want to run three 30amp 3 phase ac circuits in the same raceway, do I need to de rate and if so how much?

 

[petersonra]

Can you put 3 three phase circuits in the same raceway?

I want to run three 30amp 3 phase ac circuits in the same raceway, do I need to de rate and if so how much?

what are you "derating" for? ambient temperature? number of current carrying conductors in the raceway?

what is your calculated load?

 

[cfrancka]

22.2 amps per unit. I am asking do I need to derate for current carrying conductors?

 

[petersonra]

22.2 amps per unit. I am asking do I need to derate for current carrying conductors?

Table 310.15(B)(3)(a) may be of some help. Also Table 310.15(B)(16).

Read carefully the second paragraph of 310.15(B).

Incidentally, instead of "calculated load" I should have asked what the required ampacity of your conductors is.

 

[cfrancka]

Thanks for the help looks like I use 70% of table.

 

[Smart $]

Can you put 3 three phase circuits in the same raceway?...

Yes.

Thanks for the help looks like I use 70% of table.

That's correct for 7-9 current-carrying conductors.

Any correction for ambient?

 

[kwired]

note that if it is not possible to run all of your loads at the same time you can reduce the conductor count for application of 310.15(B)(3)(a).

2014 NEC even added text to the notes below the table to help clarify some of the situations that were questionable before, but they also added text indicating they want you to count spare conductors in the raceway - someday they might be used.

 

[cfrancka]

Yes.


That's correct for 7-9 current-carrying conductors.

Any correction for ambient?

Wouldn't think running pipes inside not on the roof.

 

[Smart $]

Wouldn't think running pipes inside not on the roof.

Just asking. Run inside is no assurance ambient correction is not required.

 

[kwired]

Wouldn't think running pipes inside not on the roof.

Some boiler rooms, steel mills or similar, hot dip galvanizing or similar applications, and more places not mentioned could have higher ambient temps then the rooftop above them.

 

[cfrancka]

Some boiler rooms, steel mills or similar, hot dip galvanizing or similar applications, and more places not mentioned could have higher ambient temps then the rooftop above them.

This is going in an office building.

 

[Smart $]

This is going in an office building.

IMO, most everyone ignores ambient temperature correction for wiring inside office buildings.

 

[ActionDave]

IMO, most everyone ignores ambient temperature correction for wiring inside office buildings.

Some of us do it very intentionally.