Ragin Cajun
Senior Member
- Location
- Upstate S.C.
Have a new project where the client wants to install 26 of these little monsters to an existing facility. To supply them I need to install a new 480-120/208V transformer and two new panelboards. Each unit is 4.1KW at 208V (19.7A and manuf recommends 2P-20A breaker). They are considered "non-continuous" loads.
I am trying to come up with a defendable, reasonable "diversity" factor to size both the transformer and a KW value to use to verify the capability of the existing service.
Anybody have any ideas? On one hand I thought to use the diversity factors for the number of units in a apartment complex, or 34%. Yes, I know it's oranges and apples, but I needed to start somewhere. That gives me a 45 KVA transformer.
Table 220.55, gives a demand of 30%. This doesn't look unreasonable for the application but likely still conservative.
This is a VA facility where the staff must wash their hands before they see each client. No medical "procedures", just check-ups, consultations, etc.
As for the connection at each heater, I am debating on using a 20A twist lock plug/recpt or simply hard wire. I lean towards the twist locks to make servicing simple. I also am considering locking devices at the panelboards but with the twist locks that might be overkill. Feeders will be #10 AWG for Vdrop. Anything larger would be impossible to terminate.
Thoughts?
Thanks ahead of time,
Ragin Cajun
I am trying to come up with a defendable, reasonable "diversity" factor to size both the transformer and a KW value to use to verify the capability of the existing service.
Anybody have any ideas? On one hand I thought to use the diversity factors for the number of units in a apartment complex, or 34%. Yes, I know it's oranges and apples, but I needed to start somewhere. That gives me a 45 KVA transformer.
Table 220.55, gives a demand of 30%. This doesn't look unreasonable for the application but likely still conservative.
This is a VA facility where the staff must wash their hands before they see each client. No medical "procedures", just check-ups, consultations, etc.
As for the connection at each heater, I am debating on using a 20A twist lock plug/recpt or simply hard wire. I lean towards the twist locks to make servicing simple. I also am considering locking devices at the panelboards but with the twist locks that might be overkill. Feeders will be #10 AWG for Vdrop. Anything larger would be impossible to terminate.
Thoughts?
Thanks ahead of time,
Ragin Cajun