Transfer switch for generator

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Old 07-03-18, 09:59 AM
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Transfer switch for generator

I'm thinking of mounting a transfer switch for my electrical generator on the main breaker panel which is outside recessed in concrete. I was originally going to mount right next to it, but it's going to be difficult to make a knockout hole big enough on the right side of the box. I was thinking instead of actually going through and making a 2 inch (or slightly larger) hole right below the breaker and mount the transfer switch inside. The other side of the main breaker is the inside garage and there is only about 2 inches of cement. I plan on later in the future installing a solar system with the batteries inside the garage anyways.

Obviously, If I create the hole below the breaker, I'll shut off the power and use the generator to power my power tools.





I would like your opinions and which hardware I would need to accomplish this.
 
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Old 07-03-18, 06:52 PM
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The power feed (2 fat black wires and other wires accompanying them) go to another, large, panel. You can put a whole house transfer switch (has one large transfer handle instead of 6 to 12 small handles) in its own box near that panel. Withdraw the other ends of the aforementioned fat wires from that large panel and run them into the transfer switch. Connect a new set of comparably fat wires between the transfer switch common terminals and that large panel.

Run a new cable (hot-hot-neutral-ground, probably 10 gauge to 6 gauge depending on expected future generator size) from the remaining terminals of the transfer switch to the desired location of the generator inlet (male receptacle).

A disadvantage of putting the transfer switch midway between the two panels is, when you cut the existing fat wires in the middle, the ends will be too short to reach the transfer switch terminals.
 

Last edited by AllanJ; 07-03-18 at 07:08 PM.
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Old 07-03-18, 09:45 PM
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We see the wires going down to the inside panel. How do they get to the inside panel ?
Down and then into the back of it ?


Since you are considering putting the disconnect inside.... it may be easier to work thru the main panel.
 
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Old 07-04-18, 02:32 AM
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The cables seem to go down the main breaker and to the right about 30 feet to the main service panel also recessed in concrete. Here, the cables seem to come from the bottom. The top cables seem to go to the second story of the house. The main service panel is in a 20 inch column between the kitchen and dinner area. Behind it is the electric range. Realistically speaking, I'd prefer of tapping into the main service panel cause it's closer to the back of the house where I want to place the power generator, but it's location is a bit cumbersome and I would really have to dig into the concrete and am afraid of cracking the thinner wall or cutting an existing cable in the process. I already have a L14-30 inlet box and 40 feet of extension cable for the generator. From the main service panel to the back of the house, there is still about 15 more feet to cover (the dining room).

By putting the transfer switch inside the garage I can still put a thinner conduit ( I'm guessing 3/4 inch for four 8 AWG wires) along the roof about 10 feet back and make a smaller hole to the outside to place the L14-30 inlet box.

I also plan to on adding a SPD and I don't really have any more room in my main service panel. So I would add a breaker box next to the transfer switch in the garage and put it there.


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Last edited by PJmax; 07-04-18 at 10:44 AM. Reason: Grammar (MOD:added main service panel picture)
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Old 07-04-18, 05:43 AM
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Because your primary large breaker panel is also nested in concrete, it is going to be a tossup whether you put a whole house transfer switch near the meter box and disconnect or near the primary breaker panel. Other factors such as proximity to where the generator inlet and generator will be will help break the tie.

It may be necessary to unhook the fat wires at both ends and pull them back and forth to get the end destined for a transfer switch out the proper conduit extension to the transfer switch and string additional wires from the transfer switch to the other, nearby, panel.
 

Last edited by AllanJ; 07-04-18 at 06:22 AM.
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Old 07-04-18, 11:00 AM
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Posted a picture of your panel. I'm noticing an incorrect and possibly hazardous connection to the main lugs. What are those white and black wires for attached to the lugs ? Those two wires look to be #12 and are protected at 125A.

The other two wires.... white and black out of the same conduit are also a red flag. A white wire connection to one half of a duplex breaker is against code. It looks like someone tried to get 240v from two duplex circuit breakers. Another major no no.
 
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Old 07-04-18, 11:16 AM
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The double lugged wires go to the AC inverters on the roof. That's how the technicians installed it. They have their own breaker box on the roof. At some point they lost the cable fishing hook and didn't have anymore black wire. The guys had a real bad day. They almost dropped my 18,000 BTU mini split unit carrying it up the roof too .Yeah, I know that needs to be taken care of, but I don't have any more room on my current panel as of now.

I think the used the white wire to send up the rest of the cable. Well actually the other way around. I'm guessing they tied their remaining white wire to the original black wire and pulled it up. My laundry is on the second floor and the receptacle has the conduit that goes straight to the roof. I think that's where they tied the rest of the wire. Haven't checked it. Once I get a chance I'll pull it apart and take a photo, since I have to pull the main breaker to check it.

There is a black wire connected to the breaker, but can hardly be seen. It goes to a 120Volt AC receptacle.
 
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Old 07-04-18, 11:47 AM
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Here is a side view of the service panel inside. There is about 8 inches on both sides oh the panel and about 22 inches from the window to the wall perpendicular to the panel.


I keep going back and forth whether to place the transfer switch on the main panel or on the service panel inside. Also whether to use a 10 circuit generator transfer switch or a double throw switch. In the end it comes down to cost.
 
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Old 07-06-18, 08:47 PM
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A multi-circuit (the 10 circuit) transfer switch unit, if decided upon, will need to be installed at the primary breaker panel in the vicinity of kitchen/dining area. A fat nipple or conduit needs to be installed there to string approximately 22 conductors mostly 12 and 14 gauge (for a 10 circuit transfer switch unit) into the existing panel.

A whole house transfer switch (a large double throw switch) can be installed at either panel (your choice).
 
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Old 07-06-18, 08:53 PM
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How wide should the nipple our conduit need to be?
 
 

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