confused about generators

[S-117]

i'm in the market for a generator for my house. I am confused about transfer switches. All the ones I see on amazon or homedepot are basically small subpanels that power only a few circuits, which is very restrictive.
Isn't there a transfer switch that goes on the load side of the meter and then feeds the main panel? I figure since generators are 240v power, setting up the switch in this manner allows me the flexibility to upgrade generator size if necessary to provide the amperage I feel I need.

I saw a generac smart ATS which costs $1000, but I can manually load shed however I see fit.

 

[Hv&Lv]

http://www.nrppd.com/sites/nrppd/files/PDF/GenerLink-Operating_Manual.pdf

 

[mike_kilroy]

Sounds like maybe you are noT a professional electrician with this question? It may not be appropriate here, but if it is, I would suggest you call generac and ask for your free home quote to get FACTS. Your $1000 and concept is wrong. For instance a quote from this week:

1 22kw w/200amp Switch
ATS- 200a
Battery- $110
Installation- $2000
Shipping- $85
Ultralite Pad- Standard
$2,326.70 TOTAL OF ABOVE

YOU do the math: this 200amp transfer switch indeed goes between the meter and the house electric panel for full house switch over. Show me where the switch itself cost more than a few hundred dollars?

 

[electrofelon]

Unfortunately the code is very silly and requires generator and transfer equipment to be able to carry the entire load calc (I could see for critical loads but not convenience like a typical resi generator). This makes putting, say, an 11kw generator on a whole house problematic. I do it all the time here in upstate NY where things are real lax and there are no permits for things like this, bit could be an issue in nanny state areas.

Note that my previous comment in for automatic transfer equipment. If manually transferred, you can be the load decider per code.

Also, many auto transfer switches have load shed capabilities by running thermostat circuits through them.

If you are thinking along the more economical manual transfer and portable generator side of things, you can simply use an interlock and backfeed the main panel

 

[S-117]

Sounds like maybe you are noT a professional electrician with this question? It may not be appropriate here, but if it is, I would suggest you call generac and ask for your free home quote to get FACTS. Your $1000 and concept is wrong. For instance a quote from this week:

1 22kw w/200amp Switch
ATS- 200a
Battery- $110
Installation- $2000
Shipping- $85
Ultralite Pad- Standard
$2,326.70 TOTAL OF ABOVE

YOU do the math: this 200amp transfer switch indeed goes between the meter and the house electric panel for full house switch over. Show me where the switch itself cost more than a few hundred dollars?

https://www.amazon.com/Generac-RXSW2...gateway&sr=8-1
$700 for just the switch




I have to say, you sound rather confrontational. A large portion of your response is meaningless and unnecessary.
Probably something to work on if you have trouble with people not liking you.

 

[S-117]

Unfortunately the code is very silly and requires generator and transfer equipment to be able to carry the entire load calc (I could see for critical loads but not convenience like a typical resi generator). This makes putting, say, an 11kw generator on a whole house problematic. I do it all the time here in upstate NY where things are real lax and there are no permits for things like this, bit could be an issue in nanny state areas.

Note that my previous comment in for automatic transfer equipment. If manually transferred, you can be the load decider per code.

Also, many auto transfer switches have load shed capabilities by running thermostat circuits through them.

If you are thinking along the more economical manual transfer and portable generator side of things, you can simply use an interlock and backfeed the main panel

Thanks for the info. I'm an engineer and I never designed a home with a generator capable of carrying the entire load. I have also never seen a set of plans with such a large generator.

I have not seen a product capable of doing what I am trying to achieve, which is having a manual switch on the line side of the main panel to which I can hook up a portable generator of my choosing. I really dont want to spend on a smart switch that costs more than a 10kw portable generator. https://www.amazon.com/s?k=9000w+generator&ref=nb_sb_noss_1

 

[mike_kilroy]

https://www.amazon.com/Generac-RXSW2...gateway&sr=8-1
$700 for just the switch




I have to say, you sound rather confrontational. A large portion of your response is meaningless and unnecessary.
Probably something to work on if you have trouble with people not liking you.

Sorry you think of me as a controversial. You ask like a user, not like an electrician. I answered you that yes, a switch between meter and house CB box is indeed available and being used by many today. You said it did not exist, and you said it cost $ 1000.00 for a MANUAL switch. I suppose you now realize that stand alone SPARE PART price of $ 700 is an AUTOMATIC switch. As an engineer you should know what that means. If you really want a MANUAL switch, it is available for much less than $ 700. I posted nothing meaningless or unnecessary.

 

[Hv&Lv]

What size generator are you looking at? For a whole house, there shouldn’t be a need for load shedding if it’s sized properly. If your looking at the 9-10kW you linked to, then the switch I linked will be all you need. Maybe cheaper if you check with your poco and they have a program in place to sell these.

I realize it won’t switch over automatically, but if you get an auto switch and the generator switches over automatically only to trip out on overload, you will be outside anyway switching breakers off and on to carry partial loads.

 

[electrofelon]

Ok if you don't want auto, just get one of these. This is by far the cheapest and simplest way. If you panel mfg doesn't make one, there are companies that make aftermarket ones for pretty much any panel.

https://www.homedepot.com/p/Square-...or-Generator-Interlock-Kit-HOMCGK2C/202767243

 

[kwired]

Thanks for the info. I'm an engineer and I never designed a home with a generator capable of carrying the entire load. I have also never seen a set of plans with such a large generator.

I have not seen a product capable of doing what I am trying to achieve, which is having a manual switch on the line side of the main panel to which I can hook up a portable generator of my choosing. I really dont want to spend on a smart switch that costs more than a 10kw portable generator. https://www.amazon.com/s?k=9000w+generator&ref=nb_sb_noss_1

As has been mentioned already if you are using an automatic transfer switch, code wants the generator and switch to be able to handle the connected load or have ability to automatically isolate certain loads when the remaining load is too high to run those select loads. Mostly because power can fail when unattended and it will automatically transfer and could overload things if not designed per these requirements - JMO but for other than legally required standby systems I still think that some of this is design decision and shouldn't be code requirements - but that is a different discussion there.

If you have a 200 amp supply and want to have standby power for it, you need a 200 amp transfer switch - manual or automatic. For standby power you may only have say a 12 kVA generator, but during normal operation you still are supplying the transfer switch with a 200 amp feeder, or service if a service rated transfer switch. It needs to be able to handle that 200 amp rating unless you put a smaller overcurrent protection device ahead of it, which is why you often see a smaller capacity "standby panel" that only feeds select necessary items instead of a large capacity or more complex ATS system. Manual transfer, 200 amp supply, and you want to be able to run anything in the house when in standby? Get a 200 amp manual transfer switch. You don't see much variety in those because they are all basically about the same thing. Only one to choose from from a particular manufacturer for the most part.

Another option with most new loadcenters these days is an interlock kit and backfed breaker from the generator to be used for manual transfer. This consists of an interlock device that only lets you turn on either the main breaker or the backfed generator breaker, but never both at same time. Interlock kits are somewhat expensive for no more than what they are, but still cost much less then a stand alone double throw switch, especially one with 200 amp rating

 

[S-117]

Ok if you don't want auto, just get one of these. This is by far the cheapest and simplest way. If you panel mfg doesn't make one, there are companies that make aftermarket ones for pretty much any panel.

​

https://www.homedepot.com/p/Square-...or-Generator-Interlock-Kit-HOMCGK2C/202767243​

​

thanks. perfect. crazy how a clip costs $60 though. ​

Don't find a GE one, so aftermarket it is​

As has been mentioned already if you are using an automatic transfer switch, code wants the generator and switch to be able to handle the connected load or have ability to automatically isolate certain loads when the remaining load is too high to run those select loads. Mostly because power can fail when unattended and it will automatically transfer and could overload things if not designed per these requirements - JMO but for other than legally required standby systems I still think that some of this is design decision and shouldn't be code requirements - but that is a
different discussion there.

If you have a 200 amp supply and want to have standby power for it, you need a 200 amp transfer switch - manual or automatic. For standby power you may only have say a 12 kVA generator, but during normal operation you still are supplying the transfer switch with a 200 amp feeder, or service if a service rated transfer switch. It needs to be able to handle that 200 amp rating unless you put a smaller overcurrent protection device ahead of it, which is why you often see a smaller capacity "standby panel" that only feeds select necessary items instead of a large capacity or more complex ATS system. Manual transfer, 200 amp supply, and you want to be able to run anything in the house when in standby? Get a 200 amp manual transfer switch. You don't see much variety in those because they are all basically about the same thing. Only one to choose from from a particular manufacturer for the most part.

Another option with most new loadcenters these days is an interlock kit and backfed breaker from the generator to be used for manual transfer. This consists of an interlock device that only lets you turn on either the main breaker or the backfed generator breaker, but never both at same time. Interlock kits are somewhat expensive for no more than what they are, but still cost much less then a stand alone double throw switch, especially one with 200 amp rating

I must have not looked at the right section in the code. I do not see the requirement for full load sizing.
I think the interlock option is the one I am going with
thanks for the help

 

[kwired]

​

thanks. perfect. crazy how a clip costs $60 though. ​

Don't find a GE one, so aftermarket it is​

I must have not looked at the right section in the code. I do not see the requirement for full load sizing.
I think the interlock option is the one I am going with
thanks for the help

You likely can put a lesser rated switch in a circuit if the load is under the switch rating, we do this all the time with 15 amp switches for general lighting on 20 amp circuits. If you have a 200 amp feeder and put a 60 amp switch in the feeder, chances are you can't easily land 200 amp conductors on that 60 amp switch - so it complicates things at the very least. But if you have more than 60 amps of load connected, that 60 amp switch is not enough, even with load shedding or manual transfer and manual load selection, you have more than 60 amps possible when operating on utility power.

 

[S-117]

I am curious about the wiring of breakers for a transfer switch. The manual for one says to wire but the hots. But for neutrals it says to simply connect to main bus bar.
does this condition not cause paralleling of neutrals between main panel and transfer switch? Why not wire nut the neutral within the main panel?

 

[kwired]

I am curious about the wiring of breakers for a transfer switch. The manual for one says to wire but the hots. But for neutrals it says to simply connect to main bus bar.
does this condition not cause paralleling of neutrals between main panel and transfer switch? Why not wire nut the neutral within the main panel?

For non separately derived system - you tie the neutrals together - your main bonding jumper is in the service equipment for both normal and standby power. For separately derived standby system, there is a bonding jumper ahead of the transfer switch on both systems, you must switch the neutral with the transfer switch in those installs if you don't neutral current is able to flow through bonding jumper and over normally non current carrying parts to get back to whichever source it is originating from.

 

[Little Bill]

I am closing this thread in accordance with forum rules. This forum is intended for use by electricians and electrical contractors, inspectors, engineers, and vendors with their job-related duties. We are not allowed to provide how-to advice to persons who are not employed in this industry, or persons who do not perform electrical installation or maintenance as part of their jobs. Engineers are welcome to participate, but only if their questions do not involve attempts to perform their own electrical installation, troubleshooting, or maintenance work.

If I have misread the situation, if for example you have an electrical contractor on board to perform the installation work, then send me a PM to explain the circumstances.

 

[Little Bill]

I am re-opening this thread after corresponding with the OP. He also an electrical contractor along with being an EE. I apologize for any inconvenience.

 

[S-117]

1

 

[ActionDave]

......is this not causing a paralleling of neutrals? You wouldn't wire them this way on a regular sub panel

Yes you would. It's a common conductor. There is one neutral from the utility to the service, from the service to the sub panel from the sub panel to the receptacle outlet in the living room....

 

[S-117]

There is one neutral from the utility to the service, from the service to the sub panel from the sub panel to the receptacle outlet in the living room....

but that is not what I showed in the diagram. The hot runs from transfer switch to room (since hots are wire nutted in main0 and:
-neutral from main panel bus to room,
-neutral from main panel bus to sub panel bus.
-Neutral feed (larger #8 cable) from transfer switch to main panel bus.

I've only ever seen circuits connect directly to a sub panel. I've never encountered the hots going to sub panel, then their corresponding neutrals go into the main panel neutral bus. Maybe my diagram wasn't clear enough.

 

[kwired]

want to confirm we are talking about the same condition. I removed the hots, grounds, and left only 2 circuits for simplicity.
This is what the line diagram would look like following transfer switch manual instructions.


is this not causing a paralleling of neutrals? You wouldn't wire them this way on a regular sub panel

You not showing enough of what you are doing with that setup. Is the transfer switch also a subpanel or is it just a double throw switch? Your branch circuit neutral conductors should land in same component that the branch circuit overcurrent devices are installed as a general rule.

You don't show the branch circuit ungrounded conductors so things aren't quite clear as to what you have there.

You don't show feeder neutral conductors either, just a one line representing whatever you have run as feeder conductors