Motor disconnects
- Thread starter JoeNorm
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kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
430.109(B) allows the branch circuit overcurrent device to serve as the motor disconnecting means for stationary motors of 1/8 horsepower or less.
Why no disconnect at well heads - check out 430.102(B) as well as the informational note that follows.
I see nothing that would disqualify any motor simply because it is 12 volts. You have to remember this disconnect isn't just for removing voltage hazards but also would not allow release of mechanical energy. A 12 volt motor may not have voltage hazard but can still have that energy from the output shaft when running.
Why no disconnect at well heads - check out 430.102(B) as well as the informational note that follows.
I see nothing that would disqualify any motor simply because it is 12 volts. You have to remember this disconnect isn't just for removing voltage hazards but also would not allow release of mechanical energy. A 12 volt motor may not have voltage hazard but can still have that energy from the output shaft when running.
ptonsparky
Tom
- Occupation
- EC - retired
I used to put disconnects at well heads for submersibles. Eventually, the inspectors talked me out of it.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I have installed several gate openers. They all had wall-wart type power supplies.
There are internal battery terminals you can disconnect to remove D.C. power.
There are internal battery terminals you can disconnect to remove D.C. power.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Does that qualify as a disconnect for the motor though?
Or is the wall wart plug considered a disconnecting means for an appliance and code essentially stops there?
I haven't installed many but ones I've worked with had direct connection of AC power to a controller and battery option would have been separate unit and connection to the controller. Gate was remote from the house and owner wanted power for other items in the vicinity such as post lights and receptacles for holiday lighting and such so a feeder was ran to the area anyway and a load center was located right next to the gate controller. The one I have in the most in mind was like 800 to 1000 feet away from the house.
- Location
- Bremerton, Washington
- Occupation
- Master Electrician
The exception requires a lockable disconnect at the well motor controller
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
Yes i never considered this much but as far as i can remember NEC didn’t mention voltage rating as a condition to permit the absence of a motor disconnect.
I do not have my NEC book but i do recall that under some situations that in order for the branch circuit breaker to serve as the motor disconnect it would have to be within sight or 50’ from the motor. Perhaps due to the 1/8 low hp this doesn’t apply here?
This post brings up a good point because many outdoor motors can be beyond 50’ from the breaker panel. So a disconnect would be needed
Also i would like to point out that one disconnect can serve multiple motors if its sized to code and proper horsepower rating
In many cases answering Code questions without the Code is akin to providing the time when on e has no watch 
Awaiting your return tom work (and book) it would be a great idea to sign up at NFPA and take advantage of the free access to the NEC
Awaiting your return tom work (and book) it would be a great idea to sign up at NFPA and take advantage of the free access to the NEC
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
I try to help with what I know on hand.In many cases answering Code questions without the Code is akin to providing the time when on e has no watch
Awaiting your return tom work (and book) it would be a great idea to sign up at NFPA and take advantage of the free access to the NEC
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I can't remember what year they changed the rule a bit, maybe 2005 give or take a code cycle or two. But you used to be able to use the disconnect for the controller as the disconnect for the motor when not within sight of the motor if that disconnect had locking provisions. This was used a lot in situations with MCC's because your MCC bucket had a lockable disconnect and of course is the controller disconnect as well.
Now that is mostly only an allowance for some the situations that have been mentioned here and the general rules do require a disconnect at the motor.
1/8 hp or less has and still allows the branch circuit device to be the motor disconnect. I don't know how they came up with 1/8 HP. A 1/8 HP motor that is running can certainly have enough mechanical power to be harmful, though many maybe wouldn't have enough starting torque to be too much of a threat if they were to attempt to start while working on the motor or driven load? Electrical shock hazard certainly doesn't change with HP.
Never really been any voltage limitations that applied in any way either.
Jpflex
Electrician big leagues
- Location
- Victorville
- Occupation
- Electrician commercial and residential
does current code allow a standard single gang “toggle” switch such as for lighting to be placed next to a 1/8 hp motor for the switch or allow the branch circuit breaker beyond 50’ from the motor to qualify as the motor disconnect. What if the motor has an integral motor mounted switch?
Motors rated A - F typically have a horsepower which matches their switch horsepower rating. Larger rated motors may need a higher horsepower rated switch then the motor horsepower rating if not using a molded switch or circuit breaker that is
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