277v, Assisted Living Units

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Npstewart

Senior Member
Good afternoon,

We are working on a assisted living facility. We are using PTAC units in the living units which come standard with a nema 6-15/20 receptacle. We have the option of running the PTAC units at 277 (or) running them at 208.

  • If we use 208 then ALL the load will have to be carried by the transformers increasing the size of them significantly throughout the whole building and we also only be feeding one per circuit breaker.
  • If we use 277 then we can eliminate or decrease the size of the transformers and feed multiple units with a single breaker so this would be the IDEAL way to go.


I am just worried about having 277v inside of dwelling type unit where people may or may not be mentally correct. Is there some type of locking mechanism that can go over the receptacle or should I just go with the 208?
 
T

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
Npstewart said:
Good afternoon,

We are working on a assisted living facility. We are using PTAC units in the living units which come standard with a nema 6-15/20 receptacle. We have the option of running the PTAC units at 277 (or) running them at 208.

  • If we use 208 then ALL the load will have to be carried by the transformers increasing the size of them significantly throughout the whole building and we also only be feeding one per circuit breaker.
  • If we use 277 then we can eliminate or decrease the size of the transformers and feed multiple units with a single breaker so this would be the IDEAL way to go.


I am just worried about having 277v inside of dwelling type unit where people may or may not be mentally correct. Is there some type of locking mechanism that can go over the receptacle or should I just go with the 208?
Click to expand...

The NEMA 6-15 or 6-20 is OK for a 208 or 240 volt unit. But you can't use cord and plug if you want to use 277 volt units. If the units are to be used at 277 volt they must be connected with a Chapter 3 wiring method. See 440.60.
 
N

Npstewart

Senior Member
texie said:
The NEMA 6-15 or 6-20 is OK for a 208 or 240 volt unit. But you can't use cord and plug if you want to use 277 volt units. If the units are to be used at 277 volt they must be connected with a Chapter 3 wiring method. See 440.60.
Click to expand...

How nice that there is a EXACT specific code section that answers my questions. Thanks!
 
G

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
mbrooke said:
They make 277 volt straight blade and twist lock plugs. I have seen it done with mobile equipment like restaurant equipment.

http://waterheatertimer.org/images/How-to-wire-outlets-5-750.jpg


However, being a dwelling If I'm correct it isn't allowed, but could be wrong on that.
Click to expand...
The referenced section, 440.60, applies only to single room A/Cs, not to whole house or whole dwelling A/Cs. And not to any other cord connected equipment.
You have to look elsewhere for a definitive answer on cord connecting a central A/C for one tenant's unit.
 
mbrooke

mbrooke

Batteries Included
Location
United States
Occupation
Technician
GoldDigger said:
The referenced section, 440.60, applies only to single room A/Cs, not to whole house or whole dwelling A/Cs. And not to any other cord connected equipment.
You have to look elsewhere for a definitive answer on cord connecting a central A/C for one tenant's unit.
Click to expand...


Ok got. :) My take is its allowed but hardwiring is a requirement?
 
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