Exhaust fans...hospitals / industrial plants overload protection?

[Danny89]

Today's question...

Why do I keep seeing motors typically exhaust fans in hospitals and industrial plants that are fed by a single pole 20 amp breaker but there is no fuse or overload protection for the motor.

What I know.

Ground fault and short circuit protection is typically done by the breaker size
And overload protection is supposed to be separate
Typically with rk5 fuses...a thermistor or overload heaters on a contactor.


Look at this picture. Nameplate is included.
It's fed by a 20amp single pole breaker and no overload protection. Why do I keep seeing this as if it's a typical install and no one cares about motor overload protection.


Best regards,
Danny Stump

Sent from my Moto Z (2) using Tapatalk

 

[MrJLH]

I have dealt with this similarly before. The organization I worked for was too cheap to upgrade the electrical distribution and infrastructure, as it was cheaper to just run the motor until it burns out.

 

[hbiss]

Usually single phase fan motors like that are thermally protected. The control panel only has contactors, not starters so the installer didn't notice. That's the first one that I have ever seen that it is 277. Normally 208 or 240.

-Hal

 

[Jraef]

Multiple possibilities:

The motor COULD be thermally protected, although the nameplate is SUPPOSED to tell you that so that someone looking at it will know. I see no indication of it on that nameplate, but it might be that as part of the listed assembly by the fan mfr, that was in the original instructions, or just sloppiness on the part of the fan mfr.

That is not the actual motor nameplate, it is the FAN ASSEMBLY nameplate which has motor info on it, but the ACTUAL nameplate attached to the motor itself will say it is thermally Protected (or just "TP").

That toggle switch might be a manual motor starter with a heater element, you can't tell from looking at it on the outside. If it isn't, it MAY have been when originally installed, and someone subsequently replaced it with a plain toggle switch, which would have been a violation.