Stand-By Generators

Ok, in my former business I was a electrical & HVAC contractor. In my time I have come across numerous generator installs that were not to code. The installation requirements is fairly simple on a generator. Any generator installed after 2008 must meet this requirement as it is the same in both 2008 and 2011 code books.

If you read the 2011 NEC Article 702 it covers optional stand-by system. In simple words 702.4 says that a generator must carry the entire load that is transferred to it by automatic means, if the generator cannot carry the whole load it must have load shedding installed. Load shedding is as simple as installing modules that interrupt the power going to high wattage appliances such has the HVAC, Waterheater, Dryer, Pool systems and such.

If the generator has a selected circuit automatic transfer switch then it must be able to carry all the loads that are wired to the selected circuit panel. This panel would be mounted next to the main panel and ether be a combination transfer switch or be a standard panel that is connected south of a standard transfer switch.

Combination Transfer Switch

Sub Panel with Standard transfer switch

If the generator automatic transfer switch is connected in-between the meter base and the main panel then it is transferring the whole load of the house.

Transfer switch mounted in-between meter and main panel

You can calculate the total load of the house by using this work sheet if the generator puts out more amperage than you get from that work sheet then the unit meets NEC 702.4

If the generator puts out less amperage than you get from that worksheet then it is required that high wattage appliances have a load shedding module installed to turn them off if the generator gets over loaded.

Generac load module

Do any of you currently look for this, or do you think this should or should not be looked at by a home inspector.


Samuel You a none member asking this makes me wonder why.
It looks like you have an ulterior motive .

I am currently a insurance inspector, I will be working on my Home Inspector Licensees this year. I just found this forum and signed up yesterday. Not ready to drop the 500 bux yet.

This is something I look for during insurance inspections as I have a back ground in it. I will most likely look at this once I get into home inspections.

I have asked my local code inspectors to look for this for the past 5 years and they just don’t get it or don’t want to…

In the bigger cities around me like Baton Rouge, New Orleans, and Lafayette the zoning office will not even issue a permit with out the electrician providing a load calculation.

I have had issues in the past where a generator owner had a generator that was not in compliance with 702.4 and it tripped the breaker a few times… Yes this guy was not the sharpest tool in the shed as he took a bit of wood and shoved under the breaker so that it could not trip. He burnt up his generator and it was not covered under warranty as it was not installed to code

If his unit had been properly installed the breaker would have never started tripping.

In my neck of the woods most generators are installed for hurricane outages your A/C unit only pulls 20 to 30 amps, so during a summer time power outage the generator will work fine. Now if the power goes out during the winter and the heater needs to come on that can be 15 to 20kw load… a 20kw heater will pull 80amps and the biggest air cooled generator on the market is 20kw and puts out 83amps. That leaves no head room for lights or the icebox!

In my years as a generator dealer I never sold a generator in my home town because the other guys never quoted to install the proper load shedding and the customers wold tell me your price is 1500 or 1800 higher than XXXX installer… I would attempt to explain why and they would srugg it off… The city inspector does not look for load shedding so the unit gets installed by the other guy and against the NEC. Now the customer ends up with a generator install that will trip the breaker every time the heater comes on.

Now lets say years down the line they sell the house that has a botched up generator install to an unknowing buyer…

Who is that fair to???


If the transfer switch is installed as the one pictured then the transfer switch must be listed service equipment and the one in the picture is not.

The feeders coming from the generator must comply with Part II of Article 225 which clearly states that once reaching the building there must be a disconnect (.31) and this disconnect must be rated as service equipment(.36)

A transfer switch that is rated as service equipment will have the ability to be turned to the off position meaning that neither the utility or the generator will pass power through without having to open the door.

This setup is a non-compliant installation

Not my photos, I was just using them for reference as to what each device looked like. I did not want to get that far into it on the OP.

But about the Service Ratting, I have barked up that tree about 4 years ago when they took the generator tie breaker out of the ATS. I just about turned blue in the face over it. But can we save that for another thread I promise if I talk in any detail about generac you will here all about how they stretch the code :).

Right now I am just looking for input on the load shedding


If it is not compliant then load sheading is the least of the problem

Right now, I believe back up generators are outside the scope of a typical home inspection and most association’s SOPs. Even so, I am seeing more and more generators installed in new construction as wells as retrofits (here in Florida). I think that this is an important issue and worthy of discussion. Hopefully, NACHI will develop a quality training class on this topic.

Great info…new member, non member. I don’t care, thanks for the info.

OK Mike…you play nice.

BTW…Big changes coming for me also…I will fill you in privately if interested.