Mechanically Interlocked Disconnects?

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ElectricJer

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Electrician
Has anyone seen multiple disconnects mechanically interlocked? I'd like to be able to disconnect and lock out multiple motors by throwing one lever. Thanks.
 
Welcome to the forum.

How many motors (and how big), and how many are to run at one time?
 
Jraef said:
To wit; you can buy 6 pole disconnect switches, specifically for this purpose. Simultaneously disconnect 2 x 3phase motors, 3 x 240V single phase motors, or 6 x 120V single phase motors.
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For that matter, you could use contactors to control any number of loads. The first thing that came to mind when I read the OP was a standard manual transfer switch.

I was thinking more of the desired quantity of possible loads, such as one of two (like your post), or one of three or more. Or, quantity of states, like any two of three, etc.
 
If I was calling this a "lock out" device.....I wouldn't be comfortable just interrupting control power to a bunch of motor starters. That would be cheap and easy to do. I'd be wanting what Jraef suggests and that wouldn't be cheap or easy to add after the fact. Not even sure I'd trust a shunt trip breaker feeding a MCC for "lockout" duty. But that comes closer IMHO.

Not a code guy so I can't say what is allowed.
 
Russs57 said:
If I was calling this a "lock out" device.....I wouldn't be comfortable just interrupting control power to a bunch of motor starters. That would be cheap and easy to do. I'd be wanting what Jraef suggests and that wouldn't be cheap or easy to add after the fact. Not even sure I'd trust a shunt trip breaker feeding a MCC for "lockout" duty. But that comes closer IMHO.

Not a code guy so I can't say what is allowed.
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Your instinct is correct, contactors are not allowable for LO/TO. You cannot padlock a contactor open. Shunt tripped breaker is fine, so long as the breaker is lockable.
 
Jraef said:
To wit; you can buy 6 pole disconnect switches, specifically for this purpose. Simultaneously disconnect 2 x 3phase motors, 3 x 240V single phase motors, or 6 x 120V single phase motors.
View attachment 2553136
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I found those too, and they might be the best/safest option. The rub though, is that I need to disconnect 4, 3phase 480 motors, and I need it to be fairly quick and easy so that the line operator can lock it out, remedy the problem on the line, and then close the circuit back in. (I work for a saw mill) Using these 6 pole disconnects would me that I'll need two, which isn't terrible, but I like to think that there might be something better. Also the $5,745.00 ea. price tag is a bit outrageous.
 
Jraef said:
Your instinct is correct, contactors are not allowable for LO/TO. You cannot padlock a contactor open. Shunt tripped breaker is fine, so long as the breaker is lockable.
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I vaguely remember seeing that contractors are not allowed as a means for disconnect, but I can't remember where I saw that. Do you know where that is in the code? (I scoured Article 430 NEC and couldn't find it. In fact, I was surprised by how vague that article was in describing means for disconnect)
 
ElectricJer said:
I vaguely remember seeing that contractors are not allowed as a means for disconnect, but I can't remember where I saw that. Do you know where that is in the code? (I scoured Article 430 NEC and couldn't find it. In fact, I was surprised by how vague that article was in describing means for disconnect)
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I would say it is indirectly addressed by 430.109 in that a controller is not listed as an acceptable disconnect except as specified in (6).
 
OSHA 1910.147 requires both the removal of all potential sources of energy from a machine, and also requires that it be lockable and the locking be in the control of whomever is doing the work.
 
augie47 said:
I would say it is indirectly addressed by 430.109 in that a controller is not listed as an acceptable disconnect except as specified in (6).
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Yeah, I think you're right. In my mind's eye I remember something about requiring mechanical means of disconnect. Perhaps I'm thinking of LOTO requirements from another publication.
 
ElectricJer said:
Perhaps I'm thinking of LOTO requirements from another publication.
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This happens often. Many people seem to believe that the LOTO procedures they follow are the only ones that exist.
I believe there are at least 3 different LOTO versions in OSHA publications, make sure you are following the one that pertains to your industry.

For example after opening and locking out a disconnect; to create an electrically safe work place, one needs to use a meter to verify the circuit is de-energized, however for a safe 'operator' action one may only need to verify the machine cannot restart.
 
jim dungar said:
This happens often. Many people seem to believe that the LOTO procedures they follow are the only ones that exist.
I believe there are at least 3 different LOTO versions in OSHA publications, make sure you are following the one that pertains to your industry.

For example after opening and locking out a disconnect; to create an electrically safe work place, one needs to use a meter to verify the circuit is de-energized, however for a safe 'operator' action one may only need to verify the machine cannot restart.
Click to expand...

I used to be an Air Force electrician, and I often remember Air Force Instructions (rules pertaining only to the Air Force) regarding electrical safety so I could be thinking of that.

You're right about LOTO procedure for an operator being to verify that the machine cannot be restarted.
 
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