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Discussion Starter · #1 ·
I'm getting ready to install a transfer switch in my basement for a generator to serve as a power backup for when the power goes out. I'm looking at probably installing this one: http://amzn.com/B000BQN4T2


I plan to hook it up to the circuits to control some of my media equipment, furnace, some lighting, etc.


My main question is that I have a panel and a subpanel, and the circuits that I need to connect to the transfer circuits are spread out through both of them, and unfortunately they are more than a room apart and it would be difficult (but not impossible) to run wire from one to the other. The subpanel is connected to the main panel via a 100 amp circuit. Is there any way for me to connect to the circuits I need on that subpanel without having to run wire from the transfer box near the main panel to the subpanel? Perhaps by somehow connecting to that 100 amp circuit?
 

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If you don't understand the makeup of a breaker panel and electrical distribution system any better than this, you should call a professional electrician before you kill someone or set the place on fire. Sorry to be so blunt, but if your generator starts back feeding into the electrical grid, somebody besides you could suffer.
 

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Discussion Starter · #4 ·

Quote:
Originally Posted by weaselfest  /t/1525453/question-about-backup-generator-for-media-room-calling-all-electricians#post_24561606


If you don't understand the makeup of a breaker panel and electrical distribution system any better than this, you should call a professional electrician before you kill someone or set the place on fire. Sorry to be so blunt, but if your generator starts back feeding into the electrical grid, somebody besides you could suffer.
Admittedly I'm no electrician, but I did wire my entire basement, including the subpanel (and no fires or electrocutions in the 10 years it's been "live"). Not sure why you mention backfeeding when I was pretty clear that I plan to install a transfer switch which (at least to my knowledge) eliminates that concern.


As for the interlock kit, I'm pretty sure there are legality issues with those, at least in the area I live.
 

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Quote:
Originally Posted by ScoHo  /t/1525453/question-about-backup-generator-for-media-room-calling-all-electricians#post_24558745


Is there any way for me to connect to the circuits I need on that subpanel without having to run wire from the transfer box near the main panel to the subpanel? Perhaps by somehow connecting to that 100 amp circuit?
There is one way to do it without extra wiring between the transfer switch/main panel and the subpanel, but, most likely, will not work. That's because the subpanel will be limited to 20A. I have no idea how much load you have in the subpanel, but I'm guessing more than 3.84kVA (limit for 20A at 240V). If that limitation is ok for you, you would disconnect the subpanel feeder from the 100A breaker in the main panel and connect it to the 20A, 2-pole breaker in the transfer switch. So the entire subpanel would have access to your generator. You will need some special splice to transition from the #12 wire from the transfer switch to your existing 100A feeder.

 

Obviously, the best way to do it would be to rewire the circuits you want on generator to the new transfer switch.
 

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Quote:
Originally Posted by MrEscu  /t/1525453/question-about-backup-generator-for-media-room-calling-all-electricians#post_24562325



Obviously, the best way to do it would be to rewire the circuits you want on generator to the new transfer switch.

I would agree with this. One thing that may help your cause is to use 12-3 between the panel and the sub panel. It could at least hopefully result in fewer runs.
 

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Save on the time and hassle of wiring and see if getting a larger generator to run the whole house is better. It is certainly convenient and the automatic on and off makes it simple. Then your transfer switch is outside and connects at your electrical service point of entry.

 

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Jeff - depends on the need of course:

the automatic whole home transfer switch 200 amps is about $1.2K + say a 20kw auto generator @ $4k so $5.2 k investment.

For a manual switch 200 amps is about $0.8K, plus a less capable manual generator 8.5kw constant/13.5kw surge @ $1.4k so $2.2k investment.


After studying I went manual for a couple of reasons:

About $3k less investment

I can use the portable generator for other uses - offsite power, which I have a few times


Of course when on portable I have to manage my power consumption, but that's not hard just flip off non-essential circuits.

Funny thing is, I built my home with the manual transfer switch, and periodically had a few days here/there w/o power.

Then, got the generator in 2009 and since then only had to use it twice, once for 2 days and once for 4 hours.


Seems after the big east coast blackout they really upgraded the local grid here, so it's much more robust than even 5 years ago.

I'm in Hartland M59/US23 area.
 

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Quote:
Originally Posted by MrEscu  /t/1525453/question-about-backup-generator-for-media-room-calling-all-electricians#post_24562325

 

There is one way to do it without extra wiring between the transfer switch/main panel and the subpanel, but, most likely, will not work. That's because the subpanel will be limited to 20A. I have no idea how much load you have in the subpanel, but I'm guessing more than 3.84kVA (limit for 20A at 240V). If that limitation is ok for you, you would disconnect the subpanel feeder from the 100A breaker in the main panel and connect it to the 20A, 2-pole breaker in the transfer switch. So the entire subpanel would have access to your generator. You will need some special splice to transition from the #12 wire from the transfer switch to your existing 100A feeder.

 

Obviously, the best way to do it would be to rewire the circuits you want on generator to the new transfer switch.
So, the power goes out, and you would go down to the main panel with a flashlight, disconnect the wires from the 100A breaker, and find some way to connect your 3AWG conductors to a 20A breaker with 12AWG terminals, just to fire up the generator? That just doesn't seem like a viable solution to me.

 

I would run a conduit from the transfer panel to the subpanel and pull as many THHN conductors as you need to feed the circuits in the subpanel.
 

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Quote:
Originally Posted by mtbdudex  /t/1525453/question-about-backup-generator-for-media-room-calling-all-electricians#post_24568761


Jeff - depends on the need of course:

the automatic whole home transfer switch 200 amps is about $1.2K + say a 20kw auto generator @ $4k so $5.2 k investment.

For a manual switch 200 amps is about $0.8K, plus a less capable manual generator 8.5kw constant/13.5kw surge @ $1.4k so $2.2k investment.


After studying I went manual for a couple of reasons:

About $3k less investment

I can use the portable generator for other uses - offsite power, which I have a few times


Of course when on portable I have to manage my power consumption, but that's not hard just flip off non-essential circuits.

Funny thing is, I built my home with the manual transfer switch, and periodically had a few days here/there w/o power.

Then, got the generator in 2009 and since then only had to use it twice, once for 2 days and once for 4 hours.


Seems after the big east coast blackout they really upgraded the local grid here, so it's much more robust than even 5 years ago.

I'm in Hartland M59/US23 area.

Mine was pure convenience. Typically when the power is out,, I'm not around or if we're out of town. Ours runs the whole house so we have cable, Air conditioners, everything. I don't have to worry when the power is out. Moreover, in our area, we lose power a lot - so we upgraded. I had our unit installed 8 years ago and have it maintained twice per year. It runs like a top. When we are out of power, you barely know it. It even sends me a text through my security system when it comes on, goes off or has a fault.
 

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Quote:
Originally Posted by Sands_at_Pier147  /t/1525453/question-about-backup-generator-for-media-room-calling-all-electricians#post_24569042

 

So, the power goes out, and you would go down to the main panel with a flashlight, disconnect the wires from the 100A breaker, and find some way to connect your 3AWG conductors to a 20A breaker with 12AWG terminals, just to fire up the generator? That just doesn't seem like a viable solution to me.

 

I would run a conduit from the transfer panel to the subpanel and pull as many THHN conductors as you need to feed the circuits in the subpanel.
Original question was if he can do it without additional wiring to the subpanel. Agree that new wiring is the best way to do it.
 

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Discussion Starter · #14 ·
After some more investigating, it actually appears it won't be too hard for me to fish some THHN from the main panel to the subpanel through the ceiling (at least not as difficult as I originally thought). The bigger issue I'm anticipating now is placement of the transfer box. There doesn't appear to be much flexibility with the placement (at least with that one I'm looking at). My main panel has a corner on one side, and a Verizon media box on the other side so there is no room to put the transfer box next to the panel. What are my options there? Do I need to install some type of junction box, next to the transfer box and then run the wiring from the junction box to the panel?
 
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