Parallel Run

[Fred B]

Stupid question, Can parallel service service conductors be pulled through a single appropriately sized conduit or must each parallel combination be pulled through individual conduit?
Example: Residential 1P 120/240-400A. Using 4/0 parallels, can all 6 conductors be in a single appropriately sized conduit between POCO and meter/disconnect or must they be put in 2 conduits L-L-N? Price and availability of products reasoning for conductor size and parallel consideration to start with.
About 300ft from POCO to service disconnect.

 

[wwhitney]

You can run them in a single conduit if you want, but then you have to derate for more than 3 CCCs in a conduit. In your example, 80% for 4 CCCs.

Cheers, Wayne

 

[infinity]

Yes parallel THHN/THWN-2 #4/0 copper conductors could go in a single raceway and still be rated for 400 amps. {260*2*80%=416 amps}

 

[wwhitney]

For #4/0 Al on a single phase residential service, the computation is 205*2*0.8/0.83 = 395A. Does the next size up rule apply here?

Cheers, Wayne

 

[don_resqcapt19]

For #4/0 Al on a single phase residential service, the computation is 205*2*0.8/0.83 = 395A. Does the next size up rule apply here?

Cheers, Wayne

This rule is not an overcurrent protection rule. It is an minimum conductor ampacity rule and 240.4(B) never applies to ampacity rules.

The rule in 240.4(B) does not change the ampacity of a conductor. It only permits the conductor to have overcurrent protection that has a higher rating than the conductor ampacity.