ECN Forum Forums Code Related Discussion NEC & other Code issues Fusible safety switch for Air Compressor

The NEC requires a disconnecting means within sight of a motor and also on the supply side and within sight of the motors controller.

The NEC never requires that fuses, even when required by the equipment be within sight of the equipment.

But hey what do I know.....I am just a maintenance guy.

lol...present company excluded.

You're not supposed to be sure what a 'thing' is. When one wishes to be all inclusive, one will use a general term.

We're talking disconnects. In a broader sense, this discussion can apply to other devices used to shut off power ... such as valves. Safety interlocks. Blocks & clamps (for spring loads). Etc.

The issue does not limit itself to motors. Or compressors. Or heater elements. Or radio transmitters. Or ... well, you get the point.

Whatever needs stopping, I want the means for stopping it to be where I am at the time ... not three floors up, down the hall, in the third room to the left. The effect of this is to make multiple disconnects a sensible idea.

Besides the natural temptation to do as little as possible, there is the inevitable presence of Mr. Murphy on every job site. The more complex the application, the more chances there are for Murphy to make his mischief.

I few years ago, my service man was doing some work on a high rise when the maintenance man came running in very distraught and needing help. They had somehow burned up the bus duct riser going through the building. The problem started out as a “bad breaker” for the chiller on the roof, no matter how many times they reset it or adjusted the trip, the damn thing just would not hold for more than a day. It never occurred to the maintenance man that maybe the chiller might be the problem.

Resetting the breaker over and over for who knows how long, the bus just melted and was ruined which tripped the building main, then the emergency generator had kicked on, only the exhaust for the generator had not been very well placed and the building OAU was sucking the fumes in and people started to get sick. Here is where it really got bad; the building was mostly occupied by layers. The building went into receivership over this incident, because they had a booger eating idiot for a maintenance man.

Sure not all maintenance men are booger eating idiots, but you never know who will work on the equipment later. Sometimes, expensive fuses make people stop and think…sometimes, at least you hope they do.

My apologies, I thought we were discussing utilization equipment.