Add A Main Shutoff Breaker To Sub Panel?

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Old 08-16-17, 03:58 PM
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Add A Main Shutoff Breaker To Sub Panel?

Can an electrician add a main shutoff breaker to my existing sub panel? There is a cutout area above the individual ones and I assume that this is what it's for, or am I wrong?
 
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Old 08-16-17, 06:52 PM
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A few photos of the inside.
 
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Old 08-16-17, 06:57 PM
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It may be possible. The neutral lug concerns me.

The part number you posted is for the cover.
Look inside the panel..... find and post the panel model number.
 
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Old 08-17-17, 08:56 AM
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Can an electrician add a main shutoff breaker to my existing sub panel?
Why do you need a main breaker? Is the subpanel in the same building as the main panel or is it in a separate building?

Panel covers are many times manufactured to fit a variety of different panels with different confgcurations of the panel interiors. Just because the cover has a knockout for a main breaker doesn't mean that your panel can accept one.
 
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Old 08-17-17, 11:40 AM
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Yes, the main panel is outside and the sub(no main shutoff) is inside the garage. I called SquareD and spoke to the techs and the said I can put in a 200a main breaker in there. Here is the one they gave me: Square D QO 200 Amp AIR QOM2 Frame Size Main Circuit Breaker for QO and Homeline Load Centers-QOM2200VH - The Home Depot . It looks so so simple to install. I know(obviously) I have to shut the main outside. Can I use a meter to make sure power is not live to the main lines coming into the garage(if so, what do I set the meter to), or do I just try a circuit or two after I shut the main. Many thanks everyone.
 
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Old 08-17-17, 12:12 PM
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Not sure what you have for a "main" outside but it definitely must be turned off before installing the new breaker. Use a meter set to over 240VAC. Many meters have a 300vac scale. If digital set to auto AC. Checking for live circuits after turning the main off is a good extra step.
 
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Old 08-17-17, 06:34 PM
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I would not spend approximately $200 just to add a breaker to that panel. What is your reason for wanting another means of disconnect ?
 
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Old 08-17-17, 07:47 PM
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Unless your garage is detached structure from your home, you don't need main breaker in this sub-panel. Looking at how many circuits on the sub-panel, it looks like you just have a main breaker outside and this sub-panel actually is a main panel for your home. Adding main breaker doesn't really do anything other than saving few steps walking down to the main breaker when you need to service the load center.


If you really want to add the main breaker, you just have to remove lugs where red and black wire was connected and nut and screw the breaker in that location, then connect red and black wire to lugs on top of the breaker.
Very simple.

do I just try a circuit or two after I shut the main
You could use the meter as JPmax described, but your later method works fine as well. Just make sure that circuit is working with the breaker on, then test again with breaker off.
 
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Old 08-17-17, 08:29 PM
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Actually there are a few reasons why I wanted to add the main:

1- Yes, wanted to avoid needing to go outside to the opposite side of the house to shut the main(and in case of an emergency). 2- I wanted to put an interlock kit so I can power the whole panel instead of just the ten circuits I just purchased with the transfer switch(I just brought the Reliance Controls A310 CRK). The 200a breaker is only $89.00 from home depot.
 
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Old 08-20-17, 09:04 PM
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Can I use a multimeter to test the main feed to the sub panel? Would there bee to strong of current to test with the multimeter. What do I set the multimeter to test?
 
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Old 08-20-17, 09:22 PM
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Can I use a multimeter to test the main feed to the sub panel?
Voltage yes, amperage no.
 
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Old 08-21-17, 07:48 AM
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To us my multimeter, what setting do I use to check for volts(after I trip the main breaker outside) to verify that all current to the sub panel(inside the house) is dead? Will the volt test tell me there is no current? And being that I'm adding a main breaker switch to a sub panel, what is the situation with this bonding screw. Do I need to add one since I'm putting in a main switch? This is a sub panel that I'm adding a main 200a breaker to(that didn't have a main). Below is a few photos of my sub panel. Many thanks.
 
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Old 08-21-17, 10:52 AM
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Set your voltage meter to 300 volts AC (or closest higher voltage if no 300).
Will the volt test tell me there is no current?
No. it will telly pu there is no voltage. Current is amps under load. No voltage no amps.
what is the situation with this bonding screw
If you have four wires to the subpanel (H=H-N-G) you do not use the ground screw and you must have a bonded ground bar for all the grounds. (3-wire is grandfathered but no longer code compliant for new installs.)
 
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Old 08-21-17, 09:02 PM
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To us my multimeter, what setting do I use to check for volts(after I trip the main breaker outside) to verify that all current to the sub panel(inside the house) is dead? Will the volt test tell me there is no current?
You don't measure current. You measure voltage.
As ray said already, put your multimeter on 300V AC or higher. The idea is you want your meter set at higher voltage then what you are measuring. When the voltage is unkown, you are supposed to start from highest setting to find what voltage you have and switch to lower for more accurate reading. But, in this case we already know that the voltage will be near 120V and 240V.
No need for range selection for auto range digital multimeters.

You should measure voltage between each hot and neutral. If the meter reads 0 or somewhere in mV range, then you are good to go.

Since you don't know how to use multimeter, I'd say it is much safer for you do just turn the lights on at your house and turn off the main breaker and check if your lights go out. This is much safer and fool proof test.


And being that I'm adding a main breaker switch to a sub panel, what is the situation with this bonding screw. Do I need to add one since I'm putting in a main switch?
No. You leave your panel as is. Your panel still is a sub-panel even if you add a main breaker to it. The main panel is where the first breaker after the meter is. In your case, where your main breaker outside is installed is the main panel.
 
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Old 08-24-17, 06:27 PM
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Just received my main for the subpanel(photo below) and need a final verification: The main 200a panel outside at the meter, and sub panel(no main) in the garage for the branched circuits. I will be installing a 200a main breaker in the sub. I was told by square d(tech support) that I don't need a bonding screw but they sent me two. This is a sub panel that I will be adding a main shutoff to that didn't have one. So, given this situation, do I need a bonding screw in the sub or not if I add the 200a main?
 
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Old 08-24-17, 07:07 PM
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No. You don't need bonding screw. You sub-panel still is a sub-panel even after adding a main breaker.
 
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Old 08-25-17, 12:24 AM
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Do I need to add the anti corroding compound to the wires? It looks like there's some on each of them already.
 
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Old 08-25-17, 05:24 AM
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Do I need to add the anti corroding compound to the wires?
Although it is not required, it is a good idea to have them on aluminum wires.
 
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Old 08-26-17, 07:47 AM
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I believe code states ... loosely stated....if you can not physically see the main panel from the location of a sub panel it must have a disconnect on it.

I am adding one in my basement to supply a woodworking shop. The electrician said the above when talking about where to add the sub panel. if i put it on the wall i wanted to put it on, needs a main disconnect panel. if he puts it in the other location it can be just a main lug panel because its 30' away and no doors will block either panel.
 
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Old 08-26-17, 01:58 PM
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I am so sure where your electrician got that requirement from. It is not part of the NEC.
 
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Old 08-26-17, 03:20 PM
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Sounds like a misquote of the rule for hard wired equipment or appliances not in sight of the panel.
 

Last edited by ray2047; 08-26-17 at 04:58 PM.
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Old 08-26-17, 03:35 PM
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It is not required for a sub-panel, in the same building where the feeder originates, to have a main disconnect.
 
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Old 08-28-17, 06:54 AM
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I had received a response from a guy Home Owners Friend Podcast - the FREE Homeowners how-to-guide! in response to the question about the bonding screw and here is his take on it:

This is kind of a screwy situation. Because you're in a sub panel, there is no bonding with in it. Normally, you connect a generator to the main panel, which has the bonding. I almost think you need bond in the subpanel-but you can't do that when it is a subpanel running off commercial mains. I'm thinking the best option for you maybe to bond or short out the ground and neutral on the generator plug side. in some generators, such as those set up for an RV, this is already done. In most portable type generators though, it is separate. This will accomplish the bonding when you have your interlocked mains shut off. you still will be connected through to the houses ground, so you probably don't need a separate ground rod how ever it wouldn't hurt to have one near the generator
 
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Old 08-31-17, 08:30 PM
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I thought I was going to have to knock a hole in the sheetrock to install some pvc conduit and knockout a hole to run my 10/3 for the generator plug. With the panel cover off I noticed a blue flex pipe next to the main feeds with nothing protruding from it. Went into the attic and BAMMM, it was(I assume) an extra knockout ready to go to receive some romex. Taped up the end of an extra piece of romex and fished it down and came clear through. Now I guess all I need to do is run the 10/3 across the joists in the attic. I have included some photos. The flex sticks up about three feet. Do I need to cut it(the flex pipe) to lay across the joists or staple to the rafters? Also, in the photo with the ceiling(that's where I'm going to bring down the romex), do I need to bring a section of pvc up the wall and into the attic, or just staple the 10/3 down the wood to the generator receptacle?
 
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