Is an AC tube axial fan a motor?

[cncsnw]

Consider a small 120VAC fan, like this one:
http://www.jameco.com/webapp/wcs/st...toreId=10001&catalogId=10001&productId=102884

Say it is installed in an industrial control panel enclosure for cooling airflow.

It certainly looks and acts like a motor. But does it merit branch circuit protection per NEC 430.52 and NFPA79 7.2.10.1?

The above fan is rated 0.24A on 60Hz, so table 430.52 would suggest a 0.72A (rounded up to 1A) fast-acting fuse or a 0.42A (round up to 0.5A?) time-delay fuse.

I commonly see fans like these connected directly to the control power transformer, with no protection other than perhaps a 10A time-delay fuse in the ungrounded conductor of the transformer secondary.

Are there some exceptions under which this falls? Or is it just a case of "not important enough to enforce"?

Since the fan motor is marked "impedance protected" I do see that it is exempt from overload protection under 430.32(B)(4). I just don't see where it can be exempted from branch overcurrent protection.

If it does require branch overcurrent protection, does that rule out AGC (1/4" glass) fuses as well?

Thoughts and comments would be appreciated.

 

[LarryFine]

Welcome to the forum!

Is it a motor? Obviously. What specifically rides on the answer?

If it's an inspection issue, you could always ask the inspector.

 

[kacper]

Consider a small 120VAC fan, like this one:
http://www.jameco.com/webapp/wcs/st...toreId=10001&catalogId=10001&productId=102884

Say it is installed in an industrial control panel enclosure for cooling airflow.

It certainly looks and acts like a motor. But does it merit branch circuit protection per NEC 430.52 and NFPA79 7.2.10.1?

The above fan is rated 0.24A on 60Hz, so table 430.52 would suggest a 0.72A (rounded up to 1A) fast-acting fuse or a 0.42A (round up to 0.5A?) time-delay fuse.

I commonly see fans like these connected directly to the control power transformer, with no protection other than perhaps a 10A time-delay fuse in the ungrounded conductor of the transformer secondary.

Are there some exceptions under which this falls? Or is it just a case of "not important enough to enforce"?

Since the fan motor is marked "impedance protected" I do see that it is exempt from overload protection under 430.32(B)(4). I just don't see where it can be exempted from branch overcurrent protection.

If it does require branch overcurrent protection, does that rule out AGC (1/4" glass) fuses as well?

Thoughts and comments would be appreciated.

I assume this is continiuous - duty motor. The answer to your question is in section 430.32.4(B)

 

[nakulak]

why isn't a fuse ok ?

 

[cncsnw]

Is it a motor? Obviously. What specifically rides on the answer?
If it's an inspection issue, you could always ask the inspector.

This is in anticipation of a possible future inspection, hoping to have things as much in order as possible (without spending too much time and money installing unnecessary components and wiring).

Regarding fuses, I have gotten the impression that fuses used for overcurrent protection of motor loads had to be branch rated, and that that implied class CC, J, RK1, RK5, T, etc. (and excluded midget or AGC).

In any event, a strict reading seems to require fuses dedicated to overcurrent protection of the fan, not exceeding 300%. I rarely see such fuses in other manufacturers' cabinets.