feeder calc question.

Status
Not open for further replies.
S

stew

Senior Member
Location
federal way,washington
I have an install coming up for 3 -5 ton ac units. 36mca/60 max breaker or fuse. Will need a sub as thier are only 3 spaces left in the 30 space ch single phase 200 a panel in this building. if i were to use a sub panel adjacent to the main would i sisze the feeders to this the same as you would do for a multimotor load? 125%of the first and the sum of the rest? Thinking about using a 125 a panel w/3 60 two poles for the units and # 1 cu feeders correct?
 
install coming up for 3 -5 ton ac units

install coming up for 3 -5 ton ac units

Hey stew
I dont understand, if you have 3 space's left in the original panel and your install is single phase you only need 2 spaces out of the panel
 
stew said:
I have an install coming up for 3 -5 ton ac units. 36mca/60 max breaker or fuse. Will need a sub as thier are only 3 spaces left in the 30 space ch single phase 200 a panel in this building. if i were to use a sub panel adjacent to the main would i sisze the feeders to this the same as you would do for a multimotor load? 125%of the first and the sum of the rest? Thinking about using a 125 a panel w/3 60 two poles for the units and # 1 cu feeders correct?
Click to expand...


That will work.
An other way, would be to put some of the branch circuits in the sub and the ac's in the 200 amp panel. Then you could reduce the size of the feeder to the sub.
 
good call on the sub with the smaller circuits. just like a friggin lite bulb ononly mine was dimmer. and by the way wireway an hvac unit of 5 tons is a 2 pole load fyi
 
stew said:
good call on the sub with the smaller circuits. just like a friggin lite bulb ononly mine was dimmer. and by the way wireway an hvac unit of 5 tons is a 2 pole load fyi
Click to expand...
I misunderstood your original post, I thought you meant 3 to 5 ton not 3 5 ton unit's
 
wireways said:
I misunderstood your original post, I thought you meant 3 to 5 ton not 3 5 ton unit's
Click to expand...
That's why I use words for quantity before a number, such as "one 3-phase service," "two 3-gang boxes," or "three 5-ton units."
 
Status
Not open for further replies.
Top