Brain fart - cable sizing single phase and 3 phase

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Telaid

Member
This is sort of simple but i need another opinion. If im sizing service cables for a single phase, 200 amp 3-wire panel, 120/240 i have 100 amps on each leg max right? so I can size cable to be a 3awg? As opposed to a 200 amp 3 phase 4 wire 208y/120 panel with 200 amp on each leg. which would need 3/0 service conductors? Just a general question so im not looking at distance of run, cable type etc.

Thanks
Ron
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Ron,
It is the same for both systems. If the breaker is a 200 amp breaker, each pole has a trip unit set at 200 amps. The conductors must be protected at or below their ampacity.
Don
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Ron, remember that 200a @ 240v is twice as much power as 200a @ 120v.

In other words, 100a @ 240v would be no more power than 200a @ 120v would be.
 
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