georgeswe
Senior Member
- Location
- The Republic of Southern California
Well I have run into numerous problems with nameplate ratings on A/C units. The plan says one thing and then when the unit arrives its a diffrent story. What we have done is I told my Foreman to only run the appropriate conduit untill the unit shows up. That way when the namplate says we need to fuse the unit at 25 amps instead of the 20 the engineer has inputed on the plan we can install the correct conductor size.
Well on the job we are currently working on the General had a meeting with my foreman and had us put all the owner changes on a plan as well as the max fuse /or circuit breaker ratings for the installed A/C units. The nameplates state 30 amps max fuse or circuit breaker. The Engineer is insisting on following her plan and installing 40 amp circuit breakers and fuses to allow for start up aperage. I always thought that the manufaturer nameplates already had this factored in, is that correct or have I been wrong all these years? I have never had a problem with a unit not starting and tripping breakers when I used the Max ratings on the nameplate. Is there a code section that would back up my argument where the nameplate rating superceed her circuiting??? I have been looking at 440.4 but the last portion of the explanation is confusing me a bit.
In my NEC 2005 handbook there is a paragraph that reads:
When a brach-circuit selection current is marked on a nameplate, it must be used instead of the rated-load current to determine the size of the disconnecting means, the controller , motor branch-circuit conductors and the overcurrent protective devices for the branch circuit devices and motor. The value of branch circuit selection current is always greater than the marked rated-load current.
Well on the job we are currently working on the General had a meeting with my foreman and had us put all the owner changes on a plan as well as the max fuse /or circuit breaker ratings for the installed A/C units. The nameplates state 30 amps max fuse or circuit breaker. The Engineer is insisting on following her plan and installing 40 amp circuit breakers and fuses to allow for start up aperage. I always thought that the manufaturer nameplates already had this factored in, is that correct or have I been wrong all these years? I have never had a problem with a unit not starting and tripping breakers when I used the Max ratings on the nameplate. Is there a code section that would back up my argument where the nameplate rating superceed her circuiting??? I have been looking at 440.4 but the last portion of the explanation is confusing me a bit.
In my NEC 2005 handbook there is a paragraph that reads:
When a brach-circuit selection current is marked on a nameplate, it must be used instead of the rated-load current to determine the size of the disconnecting means, the controller , motor branch-circuit conductors and the overcurrent protective devices for the branch circuit devices and motor. The value of branch circuit selection current is always greater than the marked rated-load current.
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