crispysonofa
Senior Member
- Location
- New England
- Occupation
- Electrical and Security Contractor
Hello thank you for reading this,
I have 2 Rooftop units that I am wiring on a farm. These are a bit larger than previous ones that I have done and I want to ensure that I do this correctly and also want to make it cost effective. The units have electric heat stages installed and it is accounted for on the nameplate bringing it to 104 amps @ 240V for the heat, Max fuse or breaker size is indicated 150 Amps as this takes into account the sizing for 125% but since there are no breakers between 130 and 150 I understand that the 150 amp rating would be used. The Circulator\Condenser is rated for a max fuse size of 60 Amps.
When I am sizing my conductors 1/0 copper @ 75C is good for 150A , I would need at least a 2 inch conduit to accommodate the conductors for the heat stages alone to each respective unit. The space inside the unit is tight and this seems like its going to be a challenge to get 1/0 Copper into the space provided from the side of the unit. Am I missing something?
There are 3 Existing QO 200 amp panels on a trough located very close to the units on a 600A feeder. With the old units gone the panels are basically empty. Putting a 150A breaker into 2 of the panels to feed the heat on these two units seems to be the best solution. (Although I thought about looking for a 600A Nema 3R panel.) I would then load the 3rd panel with both condensers/circulators on 60A breakers. QO2150 is about $600 a piece which I know is more than double the cost of these existing panels.
I understand that I need to have a service outlet and disconnect readily accessible to the units. The existing panels are NEMA 3R and located just around a corner (6 and 10 feet respectively) from the panels/trough. Would this be an area that is up to AHJ to deem it line of sight? Should I just install a disconnect on the unit or should I bring coffee that day and use the breaker as a means for disconnect?
I very much appreciate the insight from someone with more experience in doing these larger units than myself.
I have 2 Rooftop units that I am wiring on a farm. These are a bit larger than previous ones that I have done and I want to ensure that I do this correctly and also want to make it cost effective. The units have electric heat stages installed and it is accounted for on the nameplate bringing it to 104 amps @ 240V for the heat, Max fuse or breaker size is indicated 150 Amps as this takes into account the sizing for 125% but since there are no breakers between 130 and 150 I understand that the 150 amp rating would be used. The Circulator\Condenser is rated for a max fuse size of 60 Amps.
When I am sizing my conductors 1/0 copper @ 75C is good for 150A , I would need at least a 2 inch conduit to accommodate the conductors for the heat stages alone to each respective unit. The space inside the unit is tight and this seems like its going to be a challenge to get 1/0 Copper into the space provided from the side of the unit. Am I missing something?
There are 3 Existing QO 200 amp panels on a trough located very close to the units on a 600A feeder. With the old units gone the panels are basically empty. Putting a 150A breaker into 2 of the panels to feed the heat on these two units seems to be the best solution. (Although I thought about looking for a 600A Nema 3R panel.) I would then load the 3rd panel with both condensers/circulators on 60A breakers. QO2150 is about $600 a piece which I know is more than double the cost of these existing panels.
I understand that I need to have a service outlet and disconnect readily accessible to the units. The existing panels are NEMA 3R and located just around a corner (6 and 10 feet respectively) from the panels/trough. Would this be an area that is up to AHJ to deem it line of sight? Should I just install a disconnect on the unit or should I bring coffee that day and use the breaker as a means for disconnect?
I very much appreciate the insight from someone with more experience in doing these larger units than myself.
