Every home I've lives in and many I worked on, all of them had a common switch on or right near the furnace. It was common practice at least in my area. Codes vary, but it works. I would not use one of those cheap
50cent switches though, get a heavy duty one. The reason being that motors such as the blower draw a good amount of current upon starting. I do like having a shut off right near the furnace.
Of course what you say will also work, but may be overkill. You dont need another fuse if the breaker is dedicated, and should be dedicated. A lighted switch is a nice touch too!!!
My understanding is that for a furnace, AC, well pump, etc it only needs to be lockable if it's not within direct view of the appliance or if it's more than a certain distance. The idea being if you have a switch that's five feet away and visible, you will know if someone comes along to turn it back on while you're working on it. Using a disconnect where you can pull out the disconnecting part is even better because then you can take it with you, preventing anyone from turning it back on.
But then there are appliances like an oven where no disconnect other than the breaker is required. How that gets by, while you need one for an AC for example, I don't know.
It may well vary by area, but I doubt plug/socket is outright prohibited by the NEC. Here in Sacramento, CA, our gas furnace/AC air handler is in the attic, and is plugged into a normal unswitched 15a grounded outlet, on a circuit that also has the attic light but nothing else.
This was true both for the installation when the house was new in
2002, and for the replacement higher capacity system we had installed
2 years ago (different companies, the latter of which seemed to do a
*very* thorough job, so I doubt they would have done it against code).
The outlet is on the other side of the handler from the attic entry hole, so it's not a particularly accessible disconnect either.
A fused disconnect (not just a disconnect) is not specifically required unless the manufacturer requires one. Sometimes the rating plate on a A/C compressor/condenser unit said "Maximum fuse size xx". The protection would have to be fuses somewhere. There are real cheap disconnects that are like a fused pull-out without the fuses.
Describes it right.
Direct view is limited to within 50 ft.
If the disconnect is not in direct view ("within sight of") it is OK if it can be locked open. For a circuit breaker you used to be able to use a manufacturers lock accessory that attaches to the breaker. That was dropped in the 2011 code.
For stoves you could often remove the drawer at the bottom, reach back, and unplug the stove.
A switch on the furnace meets the requirements of the NEC for a disconnect. A common AC-only switch can be used at 80% of the switch rating to switch motors (2HP max). UL includes tests that are similar to motor loads (motor load at 80% of switch rating) including opening on a stalled motor.
We've been through this in the other thread. Here is what NEC says on cords:
"Nec 422.16 Flexible cords
(A) General. Flexible cord shall be permitted (1) for the connection of appliances to facilitate their frequent interchange or to prevent the transmission of noise or vibration or (2) to facilitate the removal or disconnection of appliances that are fastened in place, where the fastening means and mechanical connections are specifically designed to permit ready removal for maintenance or repair and the appliance is intended or identified for flexible cord connection.
Nec handbook note: It should be understood that a cord-connected appliance is required to be specifically designed mechanically and electrically, to be readily removable for maintenance and repair. "
Maybe you can interpret that to allow a cord and plug for a furnace, but most of the rest of us cannot. The local codes are in the end up to the local authorities, but that doesn't change what the NEC says.
My understanding is that ANSI Z21.47 specifically prohibits using a cord and plug for gas furnaces. Maybe they don't follow that in your area, which they are free to do. Or maybe the furnace was never inspected when it was installed. I can show you condos built here, for example, that were inspected and they have no footers for the outside decks supports.
The key question is, did they pull permits? If they did, the local inspector or inspectors should have been there, typically setting up a time with you to do the inspection and I would think you would know he was there. You typically also get paperwork or a stickers in the process. Here in NJ it takes 3 inspectors for one furnace install. I would think CA would be the same or even more involved.
Which tells you perhaps something about the guys that installed it....
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