Motor Space heater size and terminal box according to NEMA standards

[parlitu]

In NEMA 01 is specified that "For machines rated 601 V and higher, accessory leads shall terminate in a terminal box or boxes separate from the machine terminal housing. What about lower than 600V? Is a terminal box required by NEMA for space heater leads? Is there a table with space heater size related to motor size in NEMA standards - it should, but I don't know where to look.

 

[jraef]

No. The only reason there must be a separate box for the heater on MV motors is because all conductors must have the same insulation level within the same wiring space. So if you had one box for both, then you would need MV cable to connect the LV heater elements, plus the space for the MV cables and MV terminations. No need to separate them at LV.

"Will work for (the memory of) salami"

 

[electricpete]

Good response from jraef. I was going to provide similar response but wasn't positive.

One additional thing is to check local and industry requirements. I do recall we had one nuclear safety related 460vac motor located in EQ harsh environment where plant licensing documents specifically required space heater and rtd leads routed through separate terminal box from main leads I can't phathom the original technical basis for that requirement, but as we investigated we found it was not something we could deviate from and we ended up doing a lot of rework to get our replacement motor to conform to the requirement.

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(2B)+(2B)' ?

 

[edison123]

In our rewinding shop, we always separate out the auxiliaries like RTD's and space heaters and provide new terminal boxes even if an OEM did not. It helps with on-site monitoring and trouble shooting (especially RTD's) while the machine is running.

Muthu

http://www.edison.co.in

 

[dpc]

Muthu,

Nice to hear from you - seems like you've been away for a while.

Regards,

dpc

 

[edison123]

Hi dpc. Yes, my business is keeping me away from visiting this place often. Great to see the vets like you still plugging away here. And the site has made some nice changes too.

Muthu

http://www.edison.co.in

 

[dpc]

It's good to be busy...