New house generator setup

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Greg1707

Senior Member
Location
Alexandria, VA
Occupation
Business owner Electrical contractor
I may have a job wiring a new house. They want the house to be generator ready. Perhaps, generator by others.
What is the best setup for this? I have seen the Siemens service panel with a space in the middle for adding the transfer switch. Is this the way to go?
 

chris1971

Senior Member
Location
Usa
I may have a job wiring a new house. They want the house to be generator ready. Perhaps, generator by others.
What is the best setup for this? I have seen the Siemens service panel with a space in the middle for adding the transfer switch. Is this the way to go?

Do they want a whole house generator set up or just run the essentials?
 

JFletcher

Senior Member
Location
Williamsburg, VA
as chris mentioned, will it be full house or partial? Manual or automatic transfer? How "ready" do they want to be?

I'd let them know that a generator will be a bit cheaper to install now than after the house is complete.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
If all they want is to be generator ready I'd say go ahead and put in a manual or automatic transfer switch and a sub-panel to handle the loads they want to put on the generator.

The next step up would be a transfer switch big enough for a whole house generator.

Either way the generator can be purchased later.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Too many unknowns here. At some point in time you'll have to make up your mind as to what type of gen-set you'll be installing. Others have given you some ideas as to what type of system to install but, for the sake of argument let's say it's going to be a whole house set-up. Make sure you use a MB panel where the neutrals can float and the EGC's are separate and bonded to the enclosure. Don't install the green grounding screw on the ground/neutral bar but install a # 8 solid bonding jumper between the EGC and floating neutral bar. That way, when you get around to installing the automatic transfer switch/disconnect all you have to do is remove the green bonding wire in the MB panel thereby converting it to a sub-panel. The auto-transfer/disconnect switch will then become your main breaker panel and you'll have to relocate your water main and electrode wires there. Just my opinion. I find it's always a PITA to separate the neutrals and grounds after the fact.
 

cpinetree

Senior Member
Location
SW Florida
Too many unknowns here. At some point in time you'll have to make up your mind as to what type of gen-set you'll be installing. Others have given you some ideas as to what type of system to install but, for the sake of argument let's say it's going to be a whole house set-up. Make sure you use a MB panel where the neutrals can float and the EGC's are separate and bonded to the enclosure. Don't install the green grounding screw on the ground/neutral bar but install a # 8 solid bonding jumper between the EGC and floating neutral bar. That way, when you get around to installing the automatic transfer switch/disconnect all you have to do is remove the green bonding wire in the MB panel thereby converting it to a sub-panel. The auto-transfer/disconnect switch will then become your main breaker panel and you'll have to relocate your water main and electrode wires there. Just my opinion. I find it's always a PITA to separate the neutrals and grounds after the fact.

If you install a service entrance rated auto transfer switch it will be the first means of disconnect. The panel will be a sub from it.
No reason to install a main breaker panel, and if you do, grounds and neutrals must be separated at install not, later when the generator shows up.
 

Greg1707

Senior Member
Location
Alexandria, VA
Occupation
Business owner Electrical contractor
20 kw generator

20 kw generator

Thanks for the responses. If we include a 20 kw generator as part of the project, do we install a service panel with built in transfer switch or install a separate transfer switch before the panel? Which is a better setup?
 

tshea

Senior Member
Location
Wisconsin
ATS Now

ATS Now

Quote the ATS with service main. Main panel will be MLO. Separate neutrals and grounds. Good to go for the genset at a later date.

I did this on my brother's house. We installed the generator 2 years later. It's a whole house unit--20kw. Runs everything except the wall oven. I installed a 60 amp 2 pole contactor that disconnects when the poco is lost.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
If you install a service entrance rated auto transfer switch it will be the first means of disconnect. The panel will be a sub from it.
That is correct.
No reason to install a main breaker panel,
True but if you don't have that transfer/disconnect in at the time of original install then you have to install a MB panel


and if you do, grounds and neutrals must be separated at install not, later when the generator shows up.
Perhaps I didn't explain myself correctly. The way I read the OP, at this point in time his customer doesn't know what type of gen-set he wants so, I made the assumption that he's not going to make up his mind right away but wants to prepare for the future. I also made the assumption that the OP would end up installing a whole house gen set with an auto transfer somewhere down the line. So, that being said, if you separate the grounds and neutrals at the beginning and bond them together with a jumper wire, when you finally do the install all you have to do is remove the jumper and relocate the water main and electrode ground wires. Is that any clearer ?
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I may have a job wiring a new house.
They want the house to be generator ready.
Perhaps, generator by others
.
What is the best setup for this?
We're all guessing here and several of us have given you some decent ideas. All I would say is if you can't get the HO's to decide on what they want to ultimately do then take the lease expensive way out, get the work and worry about the gen-set later on.
 

chris1971

Senior Member
Location
Usa
Thanks for the responses. If we include a 20 kw generator as part of the project, do we install a service panel with built in transfer switch or install a separate transfer switch before the panel? Which is a better setup?

I would go with an automatic transfer switch alongside the main breaker panel. Figure out what brand of generator and try to go with that brand of transfer switch.
 

ceb58

Senior Member
Location
Raeford, NC
In the midst of all the guessing there is one thing that needs to be addressed. What brand of generator and ATS? The customer needs to make up their mind now. If you were to install a Generac R type ATS now, they are bound now to install a Generac generator. If they found a "deal" on say a Kohler or Onan generator, it could be done but a giant pain and rewiring of the controles to get them to work together.
 

kwired

Electron manager
Location
NE Nebraska
I did two rather large homes a while back, both with multiple 200 amp panels. Both customers were not planning to purchase a generator (and neither one has yet, one being about 10-12 years since it was built, the other 6 to 8 years) but wanted to be somewhat set up for if they ever did. Both were large enough and had significant enough load that not necessarily all of the house would be desired to be supplied by a generator. One had 65kw of electric heat the other about 40 kw. Both had fireplaces they were fine with using for some emergency heat and possibly limited electric heat if the generator to be chosen can handle it.

I installed all the loads they thought they may want to be on generator in one panel. Left space between the source breaker and panel so that a transfer switch could be installed fairly easily at a later time.
 

1964element

Senior Member
Location
Chicago
If all they want is to be generator ready I'd say go ahead and put in a manual or automatic transfer switch and a sub-panel to handle the loads they want to put on the generator.

The next step up would be a transfer switch big enough for a whole house generator.

Either way the generator can be purchased later.
This is the way we do it.

Sent from my E6782 using Tapatalk
 
Im currently working on something similar to this. I'm installing a 320 amp service with 2 200 amp panels my client wants to have generator back up. A portable generator now and a stand alone generator in the near future. If I install a whole house transfer switch on one of the 200 amp panels and made everything in that panel essential for emergency use and Installed plenty of nipples between the two panels in case they pickup a bigger generator I could easily add circuits to that panel. I'm trying to put a simple put a 50 amp generator inlet outlet on the transfer switch side and be ok by code. That way they can use a portable generator now and easily add a stand alone generator in the future. Manual transfer switch from what i'm reading and the people on here seems to be the easiest route but it would be nice to have a ATS that would pair great in the future for a stand alone generator. I'm not sure if All ATS require the 12 or 24 volts from the generator to switch the load or if its held by a magnetic contactor.
 

GerryB

Senior Member
Just did this on a new modular home. I left them space on the board for the ATS. Ran my grounds and SEU from the meter so they would have enough to swing it to the ATS switch. I even put in a ground bar in my panel for them. When they (Generator company) came their electrician switched the feed and grounds to his ATS switch and re fed the 200 amp main in my panel with SER cable. Like someone mentioned, you need the main if you aren't doing the transfer switch right away.
 
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