Cutting power to a subpanel

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stardog

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Just a very general question for information purposes. I had a 100 amp subpanel installed to our detached garage a couple of years ago. To cut off all power to the subpanel in order to replace or add a circuit breaker, is it best to flip the main breaker in the main service panel at the house (thereby cutting off all power to everything), or just switch off the breakers inside the main panel that serve the subpanel? Or simply flip the main breaker inside the subpanel itself?

Just curious what is considered normal safe practice for future reference in case I have someone do some electrical work for the garage circuits.
 

ImOld

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Have the POCO shut down at the meter!:cool: Come-on, there are endless what-ifs. Normally you just flip the breaker for the sub-panel. I would hope that anyone you have working on your electrical system would know this. But then again, perhaps someone has mis-wired a circuit so that a main panel and sub-panel circuit have been inter-connected somewhere. Worst kind to find since it doesn't show up until a change is made somewhere.
 

Stuff

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Most of the time to add or replace breaker nothing else is turned off as you don't want to kill the lights, a/c, refrigerator, etc. Only if a possible problem is seen is either the sub's main or the feeder for it is flipped (depends on reason). Whole house power would not be touched.
 

WorthFlorida

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Power can be turn off at either location. If you are not comfortable working around live power, shut the breaker off at the main panel for the sub panel. At any panel, a bare ground wire or a stripped wire can sometimes get away from you and hit the live buss.
 

Jadnashua

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It somewhat depends on what you intend to do at the subpanel. Safest thing is to remove power from it and that normally would entail just flipping the breaker in the main panel feeding it. There are some things that you can do while power is still applied fairly safely like wire the neutral and ground, and the power to a breaker while it is out of the panel, then snapping it into place. You should still have safety equipment on your person for that 'what if' situation.
 
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