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Old 05-07-2010, 03:52 PM   #1
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Choosing a manual transfer swtich for 7500 w generator


Hello!

With hurricane season approaching, I am beginning to make preparations for backup power in my new house I just bought about 6 months ago. Right now, I am in the process of choosing the most appropriate manual transfer switch for my application.

I have a Generac 7500W cont. 13,500W peak 120/240v generator that has a NEMA 14-50 4 prong 50a plug on it, among others. (See picture) I bought it used at a pawn shop for $250 bucks!!!!!!




My house has two fuse panels. The first panel is on the outside of the house with four 100a breakers, one for the A/C, one for the furnace, one for the stove, and one that feeds the inside panel in the garage.

The inside panel has 10 total breakers:
Two 240v breakers, one for the dryer, and one for the water heater like this:

Eight 120v breakers for all the various rooms and outlets in the house like this: (Notice how there are two switches in each breaker)


Given my house's breaker configuration, I have narrowed it down to two main transfer switches. The first is a Reliance Controls 50 amp 10 circuit transfer switch with interchangeable breakers. This would be installed next to the garage panel inside.

Now, the question I have is: Will the 10 circuit manual transfer switch work with my indoor fuse panel for all the fuses? That is, being that my indoor panel has those 8 breakers with 2 switches on them, will I be able to wire up all of these 8 breakers with the 8 remaining circuits from the transfer switch? Or will I only be able to power half of the circuits as if they were 16 breakers instead of 8 double switched breakers?

If that is the case, my second choice is a reliance controls 100 amp utility, 60 amp generator, single circuit transfer switch like this: It would be installed in the garage between the outside 4 circuit panel and the inside panel.


In either case, this would only be for the inside panel. But I was also thinking of hooking up the transfer switch to the outside panel, either with a large single circuit transfer switch, or a four circuit transfer switch. It's not that important, I don't foresee myself using the stove when the power is out.. but it would be nice to be able to run the A/C.

I plan on using a reliance controls 50A power inlet box, and a power cord with a 14-50 plug for the generator and a twist lock plug for the inlet box. Like these:


I've also considered an interlock kit for the inside breaker panel and just wiring up the inlet box straight to the panel.

What do you think is the best setup, given my house's configuration of two fuse panels? I had a guy from the utilities company stop by and try to give me ideas, but he couldn't figure it out and never called me back.

That's why I'm asking in this forum! Because no one else seems to want to help!

I appreciate all of your great advice about choosing the right panel and I look forward to your insight. Please let's not let this get into a flame war about the dangers of installing this myself (I am experienced with home wiring), or about how dangerous backfeeding is. I've already read a ton of posts about that.

Homer

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Old 05-07-2010, 05:11 PM   #2
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Choosing a manual transfer swtich for 7500 w generator


It's really a matter of what you want to accomplish! You could put a manual transfer switch before the main panel and that would give you the option to use anything within the limits of the generators capacity. Or you can put it between the main panel and the garage panel and be limited to whatever is in that panel.

As long as you use a manual transfer switch you can feed it with any generator as long as you know what you can and can't use at the same time.

If you put the transfer switch before the main panel it would have to be service rated or you will have to install a main breaker in line before the transfer switch. But this would allow you to use you AC and stove (not at the same time). You can also install a "hard start kit" which is basically just a second capacitor for your AC bringing down the starting current to what may be within the rating of your generator if it isn't already!

It is more money to do it at the service but it gives you more options. If you decide you can live without AC and a stove and just opt to feed the panel in the garage the second transfer switch you have pictured will work fine. The first picture of a transfer switch with breakers limits you to the amount of breakers pre-installed in it.

Those 2-switch breakers you posted pictures of are double pole breakers and really shouldn't be used for single 120-volt loads! GE makes a wafer breaker that if 2 were installed side by side would look almost the same as what you have pictured and they use the same amount of space in the panel.

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Old 05-07-2010, 05:35 PM   #3
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Choosing a manual transfer swtich for 7500 w generator


Thanks for the input! I'll probably end up just installing an interlock in the sub panel... That way I can do it myself, and I don't need to have the utility company come out and cut the power from the meter...

The picture I posted of the double pole breaker: I have two of those at the top of the sub panel for 240v loads.. one for the dryer and one for the water heater. The 10 circuit transfer switch I was showing has provisions for two of these breakers, and for 8 other 120v circuits. So, I'm unsure about whether or not it'll power each of those 8 smaller "two switch" breakers, or if it'll only power 4 of them.

Homer
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Old 05-09-2010, 11:22 AM   #4
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Choosing a manual transfer swtich for 7500 w generator


I would not use the transfer switch. I would use something like this. www.interlockkit.com.
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Old 05-09-2010, 12:15 PM   #5
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Choosing a manual transfer swtich for 7500 w generator


Interlock kits are a good way to go - simple and get the job done.
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Old 05-09-2010, 07:33 PM   #6
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Choosing a manual transfer swtich for 7500 w generator


Quote:
Originally Posted by vsheetz View Post
Interlock kits are a good way to go - simple and get the job done.

Here is a picture of my sub panel. It's a Siemens sub panel that has a cut out in the top center above the two rows of breakers. There is no existing disconnect on this sub panel, it's outside. There are also extra spots below both rows of breakers.

I would have to install a disconnect breaker and a generator breaker.

If I were to install an interlock, could I use the center cut out for the main disconnect breaker and the generator breaker? Or would I have to relocate one of the breakers on the top so the interlock setup would be at the top center for the main breaker, and the generator breaker would be below and to the right?

Or could I install the main disconnect and generator breakers in the bottom, so they would be right next to each other on the right and on the left?

Can some of you post up pictures of your interlock setups? Anyone have an interlock on a panel like this?

You're right, and interlock is probably the cheapest and easiest, but i'm worried I won't be able to get the right interlock for my panel.

Thanks!
Homer
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Old 05-09-2010, 08:48 PM   #7
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Choosing a manual transfer swtich for 7500 w generator


Breaker placement will depend on the kit's design.
The panel manufacturer likely offers an interlock kit.
Have you checked www.interlockkit.com to see if they have a kit for your panel?
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Old 05-10-2010, 04:31 PM   #8
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Choosing a manual transfer swtich for 7500 w generator


Those interlockkits are designed for panels with a main breaker installed. You will have to install a main breaker in your sub-panel in order for such a kit to properly configure and operate.

It might be easier to use the Reliance panel transfer kit pictured earlier and interrupt the feed to the subpanel:

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Old 05-11-2010, 03:00 PM   #9
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Choosing a manual transfer swtich for 7500 w generator


I'm going to be installing an interlock kit on my Square D box which seems pretty straightforward, but can someone walk me through the wiring from the generator receptacle outside to the panel? I did a little online window shopping and found the following parts from McMaster-Carr that should do the trick as far as getting the power from the generator to the house:

http://www.mcmaster.com/#catalog/116/773

First of all what would be the proper type of cable for wiring from the receptacle through the basement to the panel? This wiring would be exposed (not sure if that matters or not) as the portion of the basement it will run through is unfinished. The outside wiring will be pretty straightforward as I'll only really be making a male/male extension cord about 10' long.
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Old 05-11-2010, 03:20 PM   #10
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Choosing a manual transfer swtich for 7500 w generator


Quote:
Originally Posted by Badfish740 View Post
I'm going to be installing an interlock kit on my Square D box which seems pretty straightforward, but can someone walk me through the wiring from the generator receptacle outside to the panel? I did a little online window shopping and found the following parts from McMaster-Carr that should do the trick as far as getting the power from the generator to the house:

http://www.mcmaster.com/#catalog/116/773

First of all what would be the proper type of cable for wiring from the receptacle through the basement to the panel? This wiring would be exposed (not sure if that matters or not) as the portion of the basement it will run through is unfinished. The outside wiring will be pretty straightforward as I'll only really be making a male/male extension cord about 10' long.
You "Could" use 10/4 insulated cable which will work, but it probably won't be up to code, and if you try and sell your house, it won't pass inspection. In other words, it won't add any value to your house. So, I'd recommend using 10 AWG copper cable ran through PVC or metal conduit from the sub panel to the inlet box.

I had a chance to look at that catalog page you posted, and it looks like those inlet receptacles are a bit expensive, plus they are only rated for what looks like 20 amps, max.

I'd recommend using this 50 amp inlet box that's pretty cheap on Amazon. It looks like it only has 3 prongs, but it's a 4 wire setup, the fourth conductor is on the outside circumference of the plug.
http://www.amazon.com/gp/product/B00...=ATVPDKIKX0DER


Reliance Controls PB50 50 Amp Generator Power Cord Inlet Box For Up To 12,500 Watt Generators

And rather than using a double male plug (AKA a dead man's plug), I'd recommend using this plug for the inlet box. It's also a 50 amp rated plug that you can wire up on the other end of your home made cable.
http://www.amazon.com/gp/product/B00...=ATVPDKIKX0DER

Reliance Controls LL550C 50 Amp Generator Power Cord Connector For Up To 12,500 Watt Generators

For your cable to connect from your inlet box to the generator, use 10/4 cable from Lowes or Home Depot. It's about $2.30 per foot.

Now, if your generator only has a 30 amp twist lock output, then you don't have to get these 50 amp rated plugs, you can get the 30 amp rated plugs instead.

My Generac 7500 W generator has a 50 amp dryer plug on it, so the cable I'm wiring up will use that 50 amp twist lock plug on one end (pictured), insulated 10/4 cable, and then a NEMA 14-50 Male plug on the other end to plug into the generator.

I hope that helps. I'm still trying to figure it all out myself. I'm about "this" close to ordering that inlet box and that plug, plus the reliance controls single circuit main transfer switch pictured above, all from amazon.

Homer
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Old 07-24-2012, 01:11 AM   #11
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Choosing a manual transfer swtich for 7500 w generator


Sorry to bring up an old post. The power went out for the first time since I wrote the last post and now it has me serously considering some electrical upgrades.

As I mentioned, my house has 2 panels, an outdoor panel with 4 breakers:
Stove, HVAC, Furnace, and the last breaker that feeds the indoor panel. So, with that being said, I can isolate the indoor panel from the mains, but I cant isolate the entire outside box from the mains to be able to isolate the stove, HVAC, and Furnace. I can turn those breakers off individually, but I can't feed the outside panel because there is no single main shutoff switch between the meter and the four big breakers.

I can only feed the inside panel when I have it isolated from the outside panel, by using two breakers: the outside breaker that feeds the inside panel, and an inside breaker that further isolates the inside panel from the mains and outside panel.

I was able to run pretty much everything I needed using the inside panel, except for the AC, Furnace, and stove. I can foresee it being a problem not being able to run the AC on really not days when the power goes out. It wasn't even a hot day today and it only took an hour for the house to get hot.

I'd really like to be able to isolate the main panel from the meter and feed into instead of only the interior panel to be able to run those additional circuits only located on the outside breaker.

I can't feed the interior panel back into the outside panel because there's no main shutoff once you get past the breaker leading from the interior panel in the garage.

I'd like to just add a double pole double throw transfer switch between the meter and the main electrical panel outside. That way, I know the main is disconnected from everything, and I can feed the panels in the right direction, from the outside panel running the AC and Furnace, back into the garage panel which runs all the other circuits in the house.

Anyone have any new ideas? This is the simplest thing ever. Just have a generator input receptacle underneath the meter and a double
Pole double throw breaker Inbetween the meter and main breaker. when the 200A breaker is switched from "main" to "generator", I can plug in the generator and it'll run any circuit I want in the house.

Ive seen plenty of YouTube videos where they just throw this big switch between their main panel and the generator that switches from utility to generator. Where can I get one of those?

Any help would be much appreciated.
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Old 07-24-2012, 01:15 AM   #12
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Choosing a manual transfer swtich for 7500 w generator


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