Sizing conductor and OCPD to Industrial Equipment Nameplate

J

jes25

Senior Member
Location
Midwest
Occupation
Electrician
Often we get a request to connect a machine. A customer is usually adding or changing some industrial equipment. I have a picture of a nameplate from a recent request for example. Typically, if the machine doesn't have a main OCPD integrated into it, we would look at the nameplate, consider it ALL to be continuous load (who knows if it continuous), apply the 125% factor and select the conductor and OCPD accordingly.

Then I started thinking about 240.3 and providing OCPD for the equipment itself. Considering the nameplate I have attached is there a maximum OCPD for the equipment? Is it possible to oversize the OCPD from a protection to the equipment point of view? Do you agree just taking the nameplate by 125% provides a complaint install even if a little oversized?

I would say the nameplate in question is not an "appliance" or "industrial machine" per the NEC.
 

Attachments

  • Image (5).jpg
    Image (5).jpg
    82.5 KB · Views: 39
If it's not an industrial machine then what is it? There may be another article of code that covers this piece of equipment.

The NEC definition for a continuous load is "A load where the maximum current is expected to continue for 3 hours or more".

I cannot think of a single piece of industrial equipment that I have ever interacted with that I would expect to operate at maximum current nonstop for 3 hours. Certainly it exists in theory, and I'm sure there are real world examples, but all in all I think it's fair to say that is pretty rare.

As far as this specific machine goes, there will have to be more information about the equipment itself to decide which articles apply and which ones do not.
 
jes25 said:
I don't know. What it "is" and what article applies is really is the essence of my question. I think this particular machine heat treats parts with induction.
Click to expand...
If the machine doesn't say "Maximum protection" on the nameplate or the install manual (sometimes you have to research the machine) then you are fine.

The ultimate goal is to prevent hazard. So long as the machine won't catastrophically fail and cause injury or fire then its fine. Otherwise undersize protection or put in a fused disconnect and drop the size of the fuse to the rated current. If it trips then size up the fuse.
 
You must log in or register to reply here.
Top