Whole house genset panel pre-wiring

[rjacobs]

My wife and I are building a new house in the next 1-2 years so I am starting to make my list of extraneous things I want on the house or at least setup for. I believe I want a whole house backup genset. Looking at 20KW or 22KW from Generac(open to other suggestions as well).

I dont know that I can swing the generator at time of build, but I want to prep for it. Going to have them pour a concrete pad for the generator when they pour the slab. Also will have propane or NG(tank most likely) for a gas cooktop, so gas availability wont be in question

Thinking on having the electrician wire the house through one of the Generac switch panels such as the RXG42SHA1. Thats a 200amp, 42 spot, breaker panel/generator switch.

Anybody have thoughts on this panel or my plan in particular?

 

[Stuart in MN]

Personally, I'd go with a separate transfer switch rather than one that's integral with the circuit breaker panel. It may be unlikely, but if the transfer switch portion of the integrated panel ever died you'd have to replace the whole thing.

 

[_Stang_]

Agreed, the service entrance rated ATS is cheap related to the generator. You could swing that part easy when everything else is being wired and have a nice clean install. Set the genset when you're ready, tie in and go.

Sent from my SM-G950U using Tapatalk

 

[wyliesdiesels]

20KW genset?

Geez

Is this a big house?

What loads do you have?

 

[rjacobs]

Personally, I'd go with a separate transfer switch rather than one that's integral with the circuit breaker panel. It may be unlikely, but if the transfer switch portion of the integrated panel ever died you'd have to replace the whole thing.

Agreed, the service entrance rated ATS is cheap related to the generator. You could swing that part easy when everything else is being wired and have a nice clean install. Set the genset when you're ready, tie in and go.

Any that you all recommend or is the generac branded ones good to go?

I guess I just figured the all in one was a cleaner install but as you all say if the auto transfer part shits the bed, I now have a 1000 dollar panel that could have been a 300 panel.

20KW genset?

Geez

Is this a big house?

What loads do you have?

3500sq ft or slightly larger. Definitely want to run 1 ac/heat pump, refrigerator, and a few other things. I plugged those items into the generac calculator and that's what it recommends. Not planning to run electric oven, microwave, etc... And will have gas cook top. Ac in Texas is a must in the summer, heat in winter is usually more optional but I'm running electric heat so why not.

 

[turbowoodworker]

I did this pre planning as well. Had the TS placed and wiring done at time of build. Later added the Generac 22kW and propane tank.
Based on my own personal experience only, I would not pour the pad. The location of our gen changed after we were in house and cleared a little more trees. Besides, the installers have a little pre made pad they will set it on. Quite easy.
Smart to preplan.

 

[BigGarage]

Any that you all recommend or is the generac branded ones good to go?

I've not bought one yet but I did a lot of research into them. I've seen almost nothing good written about Generac. I've seen complaints from people on the East Coast who needed their generators the last two years and spent a lot of money only to find out (according to them) that the whole house generators aren't designed to run 24 hrs. a day for days at a time.

I do not know but if you look at the BBB site here https://www.bbb.org/us/wi/waukesha/profile/electric-generator/generac-power-systems-inc-0694-15012025/complaints you can see for yourself the problems people have with Generac.

Good luck.

Dennis

 

[mm08822]

20/22 KW is not unheard of for whole house standby systems. Loads such as A/C easily drive the size up 30% to handle frequent startup inrush. The other misc loads are generally trivial - it all depends what you want connected during the outage.

I too would install a "common" 200a panel and not bother with the combined unit. Order the generator and xfer switch as a pkg later. If you are 3-5 years out from doing the gen, I wouldn't lock myself into today's features to lose out on something better later.

Once you have all of your loads finalized, do a load calc. Loads such as electric dryer, stove, hot water heat and ac units can be expected to be on load shedding. You can select the priority of each - a/c sounds like your priority. Heat and A/c are considered mutually exclusive.

There are a few things that can be done to minimize cutting in the transfer switch later.

• Locate the meter/panel far enough apart so the transfer switch can be connected in between. This lets you re-use the cable from the meter to feed the xfer sw.
• Run the GEC past the meter to the panel. This lets you intercept it and later connect in the xfer sw.
• Add ground bars in the 200a main panel and wire each branch ckt ground to to them. Doing this now eliminates having to separate later.
• Plan a 3' x 5' concrete pad on firm ground - wait if backfilling.
• Pad needs to be 18" from house and 5' from any opening - windows, vents, doors, etc. (For generac guardian series anyway.)
• Size your propane tank and line to handle the gen - both flow and duration. Provide gen specs to Propane supplier.

I have been installing generacs for almost 10 years. I do the annual maintenance for my customers. I have also picked up others to PM that weren't installed by me. I believe the biggest make/break is in a quality install and routine maintenance.
A few problems I fixed from other's installs certainly affected performance/reliability.

These are residential grade units and expected for intermittent outages - not prolonged runs or used as full time generator plant. So they're priced/built accordingly. I would have no issue installing a generac for myself as backup.

 

[HenryAZ]

My 20kw Onan has a 90amp/240v breaker, meaning it won't power the whole house. I chose this size because it will keep at least one AC unit running, as well as lights, refrigeration, microwave, computers, etc. I used a DP/DT 200amp transfer switch, which lights up the whole 200amp house panel. I have breakers marked to turn off when on genset power, such as range, dryer, welder, other AC units, etc. The DP/DT switch connects the main panel to either genset power or utility power. No chance of a backfeed.

Since only 90amps can be provided by the genset, I used a figure of 80% (about 70amps) to figure what I could power, with a margin of safety.

If you went with this type of setup, you could go ahead an install the 200amp transfer switch, and run the utility line into the transfer switch, and back to the main panel. Then just leave the DP/DT switch in the utility position until you acquire the genset and run its feed to the other set of terminals.

 

[P0234]

Plan for a battery (like a power wall) and solar in addition to the generator.

 

[sberry]

Hook the microwave to it for sure,,, ha

 

[astroracer]

Like was stated, don't pre-pour a pad. They have a pad they will drop once the location is finalized.
Many things can change between now and then so just wire the house as normal and don't jump through a lot of hoops to pre-plan for obsolete equipment...
Who knows, Generac could go under by the time you decide to do an install...
Mark

 

[jade97]

I added the transfer switch when I had my house built. I used the RTSY400A3, since I was getting a 400 A service and eventually a 38KW Generac QT Series.

With the 38KW, I needed a poured concrete pad. I had that poured during the house build as well.

My house was all electric, but I had the 500 gal propane tank installed while excavation was being completed. Since this was an underground tank, I needed to have it filled @ installation, so it wouldn't pop out of the ground......

I finally got my generator 3 years after we moved in.

 

[wyliesdiesels]

My 20kw Onan has a 90amp/240v breaker, meaning it won't power the whole house. I chose this size because it will keep at least one AC unit running, as well as lights, refrigeration, microwave, computers, etc. I used a DP/DT 200amp transfer switch, which lights up the whole 200amp house panel. I have breakers marked to turn off when on genset power, such as range, dryer, welder, other AC units, etc. The DP/DT switch connects the main panel to either genset power or utility power. No chance of a backfeed.

Since only 90amps can be provided by the genset, I used a figure of 80% (about 70amps) to figure what I could power, with a margin of safety.

If you went with this type of setup, you could go ahead an install the 200amp transfer switch, and run the utility line into the transfer switch, and back to the main panel. Then just leave the DP/DT switch in the utility position until you acquire the genset and run its feed to the other set of terminals.

20KW is NOT 90a. Its ~83a...

 

[woodzy]

Go with the Generac system, have them wire between the meter and the panel yjr Generac whole house transfer switch rated at 200 amps. When you add the generator later, you will be all set. It would be best that your gas line and electrical are real close if not, you need to decide do you want to run the gas or electric. My electrical meter was on the farthest point it could be from the gas meter. But just a 80' length of the correct cable and a couple of 14-3 for the control lines and in business.

I would have the builder either extend the gas line or install the wire at the time of building so it will be ready when you buy the generator. I have the 16K and it does everything I need.

 

[rjacobs]

I used a DP/DT 200amp transfer switch, which lights up the whole 200amp house panel. I have breakers marked to turn off when on genset power, such as range, dryer, welder, other AC units, etc. The DP/DT switch connects the main panel to either genset power or utility power. No chance of a backfeed.

If you went with this type of setup, you could go ahead an install the 200amp transfer switch, and run the utility line into the transfer switch, and back to the main panel. Then just leave the DP/DT switch in the utility position until you acquire the genset and run its feed to the other set of terminals.

Something like this?

https://www.homedepot.com/p/GE-200-...ency-Power-Transfer-Switch-TC10324R/100150463

I think im liking the manual aspect of it. I also dont mind doing manual load shedding in the main breaker panel as well if needed.

Plan for a battery (like a power wall) and solar in addition to the generator.

Nah, the cost of the solar doesnt outweigh the benefit with a 30-40 year return on investment. If I had 100 acres and could put up a big *** solar field, MAYBE, but not on a house...

Hook the microwave to it for sure,,, ha

Im more concerned with the hot tub staying hot...

I added the transfer switch when I had my house built. I used the RTSY400A3, since I was getting a 400 A service and eventually a 38KW Generac QT Series.

With the 38KW, I needed a poured concrete pad. I had that poured during the house build as well.

My house was all electric, but I had the 500 gal propane tank installed while excavation was being completed. Since this was an underground tank, I needed to have it filled @ installation, so it wouldn't pop out of the ground......

I finally got my generator 3 years after we moved in.

Im "contemplating" a 500 gallon propane tank as well, not sure if I can bury it or not. I need to go see the physical size of a 500 gallon vs. a 250. Only other use for it will be a 6 burner cook top.

I'm probably going to do 400amp service, but not sure how. Im "thinking" two 200amp boxes with the second dedicated to 100amp to run to my shop, 50 amp to the hot tub and 50 amp for a future pool. None of this would be on the backup generator. The electric company said a second meter head is $25 a month if I use zero power.

Go with the Generac system, have them wire between the meter and the panel yjr Generac whole house transfer switch rated at 200 amps. When you add the generator later, you will be all set. It would be best that your gas line and electrical are real close if not, you need to decide do you want to run the gas or electric. My electrical meter was on the farthest point it could be from the gas meter. But just a 80' length of the correct cable and a couple of 14-3 for the control lines and in business.

Gas(most likely propane) will be coming from a tank so I can put it wherever. Only other use for the tank will be a 6 burner Blue Star gas cook top.

 

[sberry]

They make a gas powered micro?

 

[rjacobs]

They make a gas powered micro?

I must have missed something...

 

[jade97]

My 400 A is 2 full panels with the tx in between.

 

[P0234]

Something like this?

https://www.homedepot.com/p/GE-200-...ency-Power-Transfer-Switch-TC10324R/100150463

I think im liking the manual aspect of it. I also dont mind doing manual load shedding in the main breaker panel as well if needed.




Nah, the cost of the solar doesnt outweigh the benefit with a 30-40 year return on investment. If I had 100 acres and could put up a big *** solar field, MAYBE, but not on a house...



Im more concerned with the hot tub staying hot...



Im "contemplating" a 500 gallon propane tank as well, not sure if I can bury it or not. I need to go see the physical size of a 500 gallon vs. a 250. Only other use for it will be a 6 burner cook top.

I'm probably going to do 400amp service, but not sure how. Im "thinking" two 200amp boxes with the second dedicated to 100amp to run to my shop, 50 amp to the hot tub and 50 amp for a future pool. None of this would be on the backup generator. The electric company said a second meter head is $25 a month if I use zero power.



Gas(most likely propane) will be coming from a tank so I can put it wherever. Only other use for the tank will be a 6 burner Blue Star gas cook top.

30-40 year ROI? Are you reading the oil industry's propaganda?

Also what's the ROI on a generator?

 

[rjacobs]

30-40 year ROI? Are you reading the oil industry's propaganda?

Also what's the ROI on a generator?

I did my own math on ROI for solar. I dont trust the guys selling solar any more than I trust oil companies. The fool that came around my house trying to sell solar basically walked away after I started asking questions(because I had done my research already) and he couldnt answer them...he was looking for suckers that didnt know any better IMO.

My current house I use right at 1000kw a month. A system which would replace my 1000kw(roughly a 10kw system) would run 30k+ dollars(minus any tax incentives) and wouldnt fit on the top of my house(I could get a 3kw system on my current roof line). My electrical bill is usually 80-90 a month(never had one in 4 years over 100, and had lots in the 45-50 range). 30,000/90 is 333 months or 27 years. So I was off a few years on my ROI estimate...

And whats the warranty on the solar panels? Last I checked was 20-25 years, although they degrade before that, so they dont even guarantee full output for that 25 years... and what about when they break and you have to replace them... etc....

Im not anti solar, wind, etc... but I dont think its mature yet. Once the government can stop subsidizing things and the free market accepts them, I believe they will be mature technologies and will have more main stream acceptance. Until then, im shy of all of those technologies.

And a generator has a simple ROI... never... until you need it, then you dont give a **** what it cost.

 

[HenryAZ]

20KW is NOT 90a. Its ~83a...

The breaker inside the genset says 89amps.

 

[Platonic Solid]

... a generator has a simple ROI... never... until you need it, then you dont give a **** what it cost.

Amen to that. I got my 20kW Generac in 2012 after being trapped in the house by fallen trees over the roads. Once I could drive out, spent many hours searching for ice. Prior to the storm I had filled garbage cans (with new bags) with water to use for bathing and flushing. What a PIA.

Here's my 20kW Generac installation info.
Has well over 300hrs. on it now. I've changed the oil & filter, that's it - nothing else. No complaints or issues. Works when I need it. Uses about 30 Gal. of Propane per day.

 

[wyliesdiesels]

The breaker inside the genset says 89amps.

Yes because no one makes an 83a breaker.

A 20kw generator will NOT give you 90a.

Do the math

 

[HenryAZ]

A 20kw generator will NOT give you 90a.

Do the math

As I mentioned, I used the 80% rule to figure my load, anyway, for a margin of safety, so I'm only using about 70amps.