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20amp breakers #220048
04/25/19 05:27 PM
04/25/19 05:27 PM
watersparkfalls  Offline OP
Member
Joined: Mar 2005
Posts: 233
Washington...Not DC
I seem to have stuck in my head that the National Electrical Code requires all commercial buildings to have a minimum of 20 amp breakers...BACK STORY: the job I am on (15 story BLDG in Seattle) has heat pumps (hydronic type) with a MAX over current protection of 15 amps of course they wired them with the cheapest disco possible being a snap switch, hence the 15 amp breaker question, and the simplest fix they want to do.

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Re: 20amp breakers [Re: watersparkfalls] #220049
04/25/19 10:19 PM
04/25/19 10:19 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,362
Estero,Fl,usa
I am unfamiliar with that rule. If the label on the HVAC unit says max breaker is 15 I think you are done. Install a 15 and it is Miller time.


Greg Fretwell
Re: 20amp breakers [Re: gfretwell] #220051
04/26/19 02:41 PM
04/26/19 02:41 PM
watersparkfalls  Offline OP
Member
Joined: Mar 2005
Posts: 233
Washington...Not DC
Thanks...What about inrush current on the breaker? Do you think not having time delay fuses will cause nuisance tripping?
Thanks,
h2o

Re: 20amp breakers [Re: watersparkfalls] #220052
04/26/19 03:43 PM
04/26/19 03:43 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 7,090
Brick, NJ USA
H2O

The factory MOCP has inrush calculated within. You have to comply with the nameplate data.

Does it say MOCP....15 amp 'FUSE' or 'HACR-CB' or Fuse/CB.


John
Re: 20amp breakers [Re: watersparkfalls] #220053
04/26/19 03:49 PM
04/26/19 03:49 PM
watersparkfalls  Offline OP
Member
Joined: Mar 2005
Posts: 233
Washington...Not DC
The nameplate says fuse or HACR breaker...
Thanks again,
H20

Re: 20amp breakers [Re: watersparkfalls] #220054
04/26/19 07:16 PM
04/26/19 07:16 PM
G
gfretwell  Offline

Member
Joined: Jul 2004
Posts: 9,362
Estero,Fl,usa
That is pretty much a slam dunk at that point, no matter if there is some local rule or not. You are required to use the manufacturer's installation instructions and on things like MOCD, it could easily be a safety issue. You could make the manufacturer happy if you just used a breaker or a fused disconnect as the local disconnecting device and still have a 20a circuit tho. We see that a lot on AC replacement units when they specify a lower MOCD than the original unit so they just change the breaker in the disconnect. Since you say they are using a snap switch there it would have to be the branch device in the panel.

Last edited by gfretwell; 04/26/19 07:18 PM.

Greg Fretwell
Re: 20amp breakers [Re: gfretwell] #220055
04/29/19 04:11 PM
04/29/19 04:11 PM
watersparkfalls  Offline OP
Member
Joined: Mar 2005
Posts: 233
Washington...Not DC
Thanks...
H20


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