Hello to all of you folks this is probably going to sound like a stupid question and I'm kind of feeling stupid for asking it but I need to know??

Ok my dad has a stand alone generator and what I need to know is how I disable it from coming on while i'm putting a 100 amp panel in place of the old fuse box that is currently in his tool shed?? Thanks so much.

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  • Usually the generator has a switch of some kind. Mine has a three position switch. The positions are on, off and automatic. If I turn it to "off," it will not turn on, no matter what. The generator may also have a separate breaker somewhere that disconnects the output from all load. If you aren't sure, try to get an electrician to take a look at it. Also, check the panel with a voltmeter before you start working on it. Make sure nothing is hot. – mkeith May 30 '17 at 6:17
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    The off position of the main switch of the generator should be fixed using a padlock. – Uwe May 30 '17 at 9:04
  • If in doubt, drain the fuel off and run the generator until it stops. – Andy aka May 30 '17 at 9:52
  • @AndyAka - I certainly wouldn't trust that on an auto-start generator, cranking the engine by the starter may be enough to energize the panel. And even if you ran it out of fuel, you don't know if maybe there's just enough fuel left in hoses to give another few seconds of runtime, enough to kill you. If you want to disconnect the generator from the panel for safety, then disconnect it (and ideally lock or tag it off so someone trying to turn on the lights doesn't turn it back on) – Johnny May 30 '17 at 17:14

Disconnect the starting battery cable on the generator. Leave a sign informing others not to reconnect it without your permission. You could even take the battery away to be extra safe.


There's nothing stupid about this. Mains electrical is serious business, and is a craft entirely separate from EE. (No offense but nobody thinks putting gas in their weedwacker qualifies them to drive a gasoline truck.) So when dealing with mains electrical, bring your best game, a good "homeowner fix-it" guidebook, and a willingness to think different - because everything is different!

While there is much good advice here on how to disable the generator mechanically, I would also look for a way to disconnect it electrically. For instance, a proper generator interlock prevents both utility supply and generator from both being turned on at the same time -- but does allow both to be turned off. E.G. in this dog-simple example: Both supply-main breakers are faced opposite: inward is on. Left breaker is off, right is on, and the interlock allows the right one to be turned off.

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Speaking of that, this is also a good time to make sure that the generator is installed to Code. A huge number of generators aren't.



Set control to manual, or press the emergency stop.
Disconnect the starter relay.
Disconnect (and lock) the circuit breaker.
Apply sign: "Maintenance lockout! Label only to be removed by Araho [phone number]".

Not all of them might be applicable to your generator.


The easiest way, if it's gas (i.e. not diesel) is to simply pull the boots off the spark plug. If it's more than one cylinder, LABEL THEM!

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