Generator Hookup to House ?

[bigdog]

What is involved, to hookup my small generator to the house.

Specifically, I want to be able to run my propane gas furnace, using the generator as a source of power.

What is needed, and cost?

Thanks !

[thinkxingu]

Originally Posted by bigdog

What is involved, to hookup my small generator to the house.

Specifically, I want to be able to run my propane gas furnace, using the generator as a source of power.

What is needed, and cost?

Thanks !

I have an exterior 50 amp outlet with a mechanical interlock on my main panel that allows my generator to power my whole panel/house. My genny, at 7K, is too small to run the whole house, so I need to shut off some breakers.

When the power is out, I fire up the genny (electric start, it's connected in early October and disconnected in May), flip the breakers I have labeled red to off, and then break the main/turn on genny circuit. I then have access to whatever I need; I just need to be able to balance what's run.

The alternative is to have a separate breaker with only the circuits the genny will run. I didn't want the extra cost, nor did I want to be limited in the number of circuits I had access to.

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[SteveO123]

You need a manual transfer switch. You can power 6 circuits with a base model. Cost about $300 plus install. It shouldn’t take your Sparky more than 2 hours to wire it for you.

Reliance Controls Corporation 31406CRK 30 Amp 6-circuit Pro/Tran Transfer Switch Kit for Generators (7500 Watts). https://www.amazon.com/dp/B000BQN4T2..._86G7BbYQS5PXC

The switch isolates your genny feed from the mains. Start your generator then flip the paddles to Gen. setting you now have safely powered that circuit so it won’t backfeed to the main line. Safe safe safe. After the calamity is over you just flip the switches back to Line setting then shut off the genny.

You can also get an automatic transfer switch but might not make $ense for a manual start genny.

Stay safe.
Steve

[8gv]

I have a friend who has his generator hooked up with just a few circuits and a manual transfer switch.

It did not take long for him to realize that being limited to using only the circuits he chose at the time of installation is, well, limiting.

For my installation, done by Hutchins Electric, there is a metal plate, a generator breaker and a receptacle for the generator cord plug.

This sounds very much like the system described in an earlier post.

The system is simple to use and my family has been trained to use it.

There cannot be any back feeding of home generated power because with this system it is physically impossible to have the main breaker on at the same time as the generator breaker.

What I like about this system is the ability to chose which circuits I wish to use, when I want to use them. My 7k generator has its limits but I can still use anything I have, just not all at once.

Some times the sump pump is a priority. Some times it's not. The good news is that is a decision that can be made whenever rather that at the installation.

Here's a link to a video of how this works:

https://youtu.be/n7DkaorEQPQ

[Slickcraft]

We have a solution like those in posts #2 & 4; a connection to the entire breaker panel with a sliding metal interlock, top right inside the breaker panel. The generator breaker switch can only be turned on if the main breaker is switched off to allow the interlock to be slid up.

I have marked all the high power circuits with red dots so I can temporally switch them off prior to connecting the generator. Then I switch back on the ones that the 7K generator can support.

Wired to top left on the panel is an alert that line power is back on as we can't see neighbors houses:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Wired to center left is a watt meter that shows load on each 120v leg of the generator.

Wired in at bottom left and positioned about a foot away is a Reliance single circuit transfer box. We used that to power the furnace with a 2K Honda generator prior to the current setup. I left it wired in as a backup.

[8gv]

Do you know what the primary reason is for investing in a generator set up?
























To prevent power failures...

[camp guy]

Okay, bigdog, here is my standard answer when it comes to electricity - call a licensed and insured electrician and have him (her) do the job.

You will get a lot of answers on this Forum from the DIYers about how easy it is to do, but I submit to you that the peace of mind provided by a qualified electrician is well worth the money you will spend. A qualified electrician will make a review of your present home electrical load and make suggestions to you about the appropriate size generator you would need to meet your needs.

Electricity is not something to fool around with at all. I have had two generators installed by qualified electricians and have had absolutely no problems.

[Kamper]

Can't really argue with "Camp Guys" advice but it all depends on your skill set.

I use a transfer switch on my furnace so I can transition quickly before the house gets too cold. For everything else, I use heavy duty extension cords and limit what I use during black-out.

The first generator I bought, was during a week long blackout. I flipped the circuit breaker and pulled the wires going into the shut-off switch by the furnace. I tied in a pig-tail to plug into an extension cord. This is not really legal but is quite common. Better to install, or have installed, a cut-off switch so you don't have to do this job by flash-light.

I also have a propane camping stove to use instead of the electric range.

[Blue Thunder]

Originally Posted by camp guy

Okay, bigdog, here is my standard answer when it comes to electricity - call a licensed and insured electrician and have him (her) do the job.

You will get a lot of answers on this Forum from the DIYers about how easy it is to do, but I submit to you that the peace of mind provided by a qualified electrician is well worth the money you will spend. A qualified electrician will make a review of your present home electrical load and make suggestions to you about the appropriate size generator you would need to meet your needs.

Electricity is not something to fool around with at all. I have had two generators installed by qualified electricians and have had absolutely no problems.

While I do have a generator hooked up like those described above that I did myself, I have a good friend who is an Electrician. He has a saying that he uses a lot. “Electricity is not a Hobby” Sound advice!!
BT

[SIKSUKR]

Its interesting because I use a portable gen rated at 5500. I dont switch off any breakers at all. I just dont use big load ones like the oven. My hot water is a tankless which comes from the boiler water so that makes a big difference. My well pump is a shallow well 2 hp I think but everything runs fine. I might see a slight voltage drop for a second when that kicks on but no issues at all. Just ran it 2 weeks ago for 6 hours. I have a setup similar to Slick and made it myself so the main breaker has to be off to energize the panel from a double pole breaker which feeds an twistlock receptacle. Works real easy and a lot cheaper than having an auto switch to a separate panel installed. Probably a few thousand dollars.

[Slickcraft]

Originally Posted by SIKSUKR

Its interesting because I use a portable gen rated at 5500. I dont switch off any breakers at all. I just dont use big load ones like the oven. My hot water is a tankless which comes from the boiler water so that makes a big difference. My well pump is a shallow well 2 hp I think but everything runs fine. I might see a slight voltage drop for a second when that kicks on but no issues at all. Just ran it 2 weeks ago for 6 hours. I have a setup similar to Slick and made it myself so the main breaker has to be off to energize the panel from a double pole breaker which feeds an twistlock receptacle. Works real easy and a lot cheaper than having an auto switch to a separate panel installed. Probably a few thousand dollars.

The electrician that installed the interlock recommended switching off circuits with electric motors prior to engaging the generator and then switching them back on one at a time. This eliminates all motors starting at once. In our case that includes the deep well pump, furnace and two heat pumps.

I did install the original single circuit Reliance transfer box myself, a very simple deal.

[Kamper]

Originally Posted by Slickcraft

... I did install the original single circuit Reliance transfer box myself, a very simple deal.

I've lent out my generator to friends and I used a transfer box that I never got around to using in my house. It's only a few minutes more than pig-tail and they can switch back to line power when it comes back.

[panjumbie]

The mechanical (sliding plate) interlock mentioned by several here and pictured in one of the posts would appear to be absent when the cover to the breaker panel is removed.

For that reason and others, it has not been permitted in some jurisdictions and by many utilities.

Backfeeding the utility can be fatal to a utility worker restoring service. The transformer feeding your property works in both directions. It will step up the 120/240 volts from your generator to the thousands of volts on the primary side. And if the outage is local and there is little other load on the primary side of the transformer, it is quite possible that the external load will be insufficient to trip the breaker on the generator.

I'm interested in whether that interlock is UL (or other listing agency) approved for that application.

John Schmidt, PE (retired)

[MAXUM]

Originally Posted by panjumbie

The mechanical (sliding plate) interlock mentioned by several here and pictured in one of the posts would appear to be absent when the cover to the breaker panel is removed.

For that reason and others, it has not been permitted in some jurisdictions and by many utilities.

I just installed one of these for generator isolation for a new subpanel I put in. The mechanical interlock is actually built into the breaker itself not part of the cover. You'd have to literally destroy the breaker to get it off and I would venture a guess this is by design. The interlock I put in is UL listed and was manufactured by Square D.

[8gv]

Originally Posted by panjumbie

The mechanical (sliding plate) interlock mentioned by several here and pictured in one of the posts would appear to be absent when the cover to the breaker panel is removed.

For that reason and others, it has not been permitted in some jurisdictions and by many utilities.

Backfeeding the utility can be fatal to a utility worker restoring service. The transformer feeding your property works in both directions. It will step up the 120/240 volts from your generator to the thousands of volts on the primary side. And if the outage is local and there is little other load on the primary side of the transformer, it is quite possible that the external load will be insufficient to trip the breaker on the generator.

I'm interested in whether that interlock is UL (or other listing agency) approved for that application.

John Schmidt, PE (retired)

Here’s the MET certification for the Square D kit:

https://www.geninterlock.com/wp-cont...ass-letter.pdf

Mine was installed by a licensed electrician with a permit from the town. The town then inspected and approved the work. Yes, removing the panel cover could defeat the system. I do not have any plans to do that.

[Rusty]

Originally Posted by panjumbie

The mechanical (sliding plate) interlock mentioned by several here and pictured in one of the posts would appear to be absent when the cover to the breaker panel is removed.

For that reason and others, it has not been permitted in some jurisdictions and by many utilities.

Backfeeding the utility can be fatal to a utility worker restoring service. The transformer feeding your property works in both directions. It will step up the 120/240 volts from your generator to the thousands of volts on the primary side. And if the outage is local and there is little other load on the primary side of the transformer, it is quite possible that the external load will be insufficient to trip the breaker on the generator.

I'm interested in whether that interlock is UL (or other listing agency) approved for that application.

John Schmidt, PE (retired)

Could you give me the "jurisdictions" and "utilities" that don't allow an interlock on the panel cover. Also do you know of any cases where someone removed the panel cover and caused damage to anything while operating a portable generator.

I do agree that an interlock that is under the cover is better and real easy to put on.

[WINNOCTURN]

Not only did we setup a (Portable) Backup Generator but 2 “SPRINGS” We finally (after16 years built THE GARAGE on the Foundation we poured back then. At that time we decide to put in the Emergency Lighting to back up our Emergency Generating System.

Having trouble loading complete Word file. Too many JPEG Files????

[WINNOCTURN]

So you have Electrical Power, especial in the Winter, don't want to FREEZ my BUTT off! OH WATER PIPES MAYBE?

HEAT???


Manual Interlock, Not that hard to install!

We have a mandatory 45 Minute Rule. Wait and the think about hooking up the Generator.

Allot of times the LIGHTS are back on by then?

To prevent power failures...

[Kamper]

If you are like me and don't have a fancy setup. Turn on your plugged in radio and set the volume to loud. When the power comes back on you will know to shut-off your generator and switch your critical circuit breakers back on.

[fatlazyless]

So ...... have to ask ..... inquiring minds want to know ..... what country to you all live in that you have the need for a backup generator?

My place is in Meredith, NH which is served by the NH Electric CoOp, and the Electric CoOp has a local service garage/home on Rt 25 in Meredith, not too far from Center Harbor.

In the very rare event the power is down due to wind, ice, falling tree, the CoOp gets it fixed usually in less than an hour and they do it automatically without me making a call.

In 26-years I have had to make a call just once when some ice messed with the individual service line and half the 220v was down which made the power go backwards or something.

The CoOp Electricity comes with service included as part of the deal. The big yellow utility trucks with the big, tall, ladder lifts are service vehicles, and the people who fix the power are utility linemen.

[loonguy]

I hate to admit it, but I share Less's perspective. In this case Less is More. In nearly 20 years in Moultonborough we have had no need for a generator (knock on wood). We do have propane for the main furnace (which needs electricity), and two fireplace/stove heaters (which do not need electricity) on battery operated thermostats as back ups to avoid freezing. The only freeze incident occurred when the propane company failed to fill our propane tank, and a generator would not have helped.

[thinkxingu]

In 11 years at our home, we've lost power for more than one whole day at least three times, sometimes up to 5 days.

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[Top-Water]

Original Post

Originally Posted by bigdog

What is involved, to hookup my small generator to the house.

Specifically, I want to be able to run my propane gas furnace, using the generator as a source of power.

What is needed, and cost?

Thanks !

Very easy to hook up. Shouldn't take that long. Happy with my set -up

TIP. Buy good electrical tape, don't get the cheap stuff two rolls usually covers the whole job. Good Luck

[MAXUM]

Hey Top Water I noticed that you have a loose connection on the number 14,587th wire.

Other than that, looks perfect Nice touch to use color coded wire.

[fatlazyless]

Woodstock Soapstone stove maker, www.woodstove.com, is in Lebanon, NH, and they make very high quality propane stoves that continue to heat when the electricity is down, so it works both with and without electricity. It runs on the pressure in the propane tank or something? High quality with a high price and not sold at Walmart?

[Rusty]

Originally Posted by fatlazyless

So ...... have to ask ..... inquiring minds want to know ..... what country to you all live in that you have the need for a backup generator

Probably the same reason most of us have health, home, or car insurance. Generators are just another insurance feature in your life. We only need them when something happens to us that the insurance policy will help us out.
Some people need a sump pump in their basement that a generator would come in real handy at times during a prolonged outage.

[fatlazyless]

Just like a 12v bilge pump on a boat, a battery powered Rule bilge pump and flipper switch could be installed in a basement as a sump pump for like 100-dollars or less, if you already have a spare 12v battery.

Apparently, the Plymouth Walmart doesn't have a backup generator, and they post signs, 'electricity outage-spoiled food-not for sale', and simply toss thousands of dollars of refrigerated food into the dumpster which is what happened recently in October????

...... so, to follow the Walmart example ....... just grab a bucket and mop!

[loonguy]

I understand the need for a generator in the circumstances addressed in other messages, but the risks of a generator remain a factor to be considered. This warning was included in today's storm warning from the National Weather Service: "If you plan on using a portable generator...be sure to observe all safety precautions to avoid carbon monoxide poisoning...electrocution...or fire. Be sure to operate your generator in a dry outdoor area away from windows...doors and vents. Carbon monoxide poisoning deaths can occur due to improperly located generators!"

Be safe!

[Barney Bear]

We have no dry outside area at our place, so we cover our generator with a small piece of plywood, weighted down with a concrete block, to keep snow and rain off of it. 🐻

[8gv]

To cover my generator I bought a small, low folding table on Amazon.

It fits around and just above the generator perfectly.

The exhaust outlet is low so there is no concern for melting the table top.

[Kamper]

I have a CO/Carbon Monoxide detector. A good idea with any type of combustion heat as well.

[StevenGilford]

I've lived in Gilford for almost 4 years now, and have had multiple power outages. Most for an hour or two, some for up to a day, and last year we were out for 5 days.

The 5 day outage prompted us to look into generators, as without a electricity we have no water, no furnace, and very limited heat. It also prevents me from working. We finally completed installation of a 12kw standby generator that automatically transfers a couple of weeks ago.

Today we woke up at 7am to a text message from Eversource saying our power was out 'in our vicinity'. We had to go outside to hear the generator to confirm that ours was out. It was nice to not have our morning impacted. We showered, breakfasted and got started with work without worrying about alternative options. The power came back on around 8:30am.

For short power outages it's very convenient, but mainly I don't want to go for 5 days without power or heat again.

[8gv]

Just don’t do the math on a cost/hour for your system so far!

[rick35]

When I had a 5500 watt portable generator I kept it in a large plastic yard box. The top lifted and the front doors opened. If the weather was good I would leave the top up but if not I would leave it closed and run a 12 inch fan in the box for cooling. Even when cold out the generator would run hot. I had it connected to a gentran switch and it worked great as long as we were home to fuel it. After the Halloween storm a few years ago we upgraded to a standby genererator.

[camp guy]

I replied earlier about this, basically, use a licensed electrician. I just read some posts wherein another thought comes to mind. A stand-by generator installed with fully automatic start and transfer also provides peace of mind to those who have homes with systems needing to be active all the time, i.e., a forced septic main from septic tank to leach field, a well-pump so you can flush your toilets, possible a security system protecting your house and contents, any one of several medical devices (C-PAP, oxygen generator, lift master stair climber). Also, what if you have company with certain needs - isn't the idea of a generator comforting to them?.

Merry Christmas (and with a generator you can keep the window lights twinkling all season) and a Happy New Year.

[bigdog]

Geezzzzz so much to read here with so many options !

First..... Thanks to all who have added to this Thread, lots of great info.

Since we loose electric power so rarely, maybe a day at most, I think I'm going to take the easy course of action, use the Generator just to power a light, Well pump, Fridge, and Pellet stove ! I can just plug into the generator with extension cords for those appliances.
Anything else I don't need.

[thinkxingu]

Originally Posted by bigdog

Geezzzzz so much to read here with so many options !

First..... Thanks to all who have added to this Thread, lots of great info.

Since we loose electric power so rarely, maybe a day at most, I think I'm going to take the easy course of action, use the Generator just to power a light, Well pump, Fridge, and Pellet stove ! I can just plug into the generator with extension cords for those appliances.
Anything else I don't need.

The only things you need to add to make the situation a whole lot easier is a mechanical interlock and exterior plug. Spend a couple hundred bucks to save all that (potentially dangerous) cord crap.

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[Downeast]

BiggD I cheated and went for the Honda 2000 by way of eliminating the heavy draw items in my house:



1 Gas cooktop vs electric
2 rinnai direct vent + wood stove - - [(if powering this directly just note, some heating units don't work with an un-bonded neutral (as found on suitcase gens)]
3 12v marine/rv water pump / 1 gal expansion tank with psi switch and 50 gal reservoir for toilets and a short shower use when power is out
4 LP clothes dryer
5 LP water heater
6 led lighting throughout the house

7 if you need a sump pump, u can use a 12v bilge pump rather than hoping a small generator will power the 110v primary pump during outages


I manufactured custom interlock plate to fit my panel. (that was a pain, but trial and error on cardboard before cutting the plate helped a ton)

the honda 2000 gen is nice as it is very quiet and efficient . That said, I dont worry about extended run times. it hardly sips fuel.

if you can keep the demand down in the house with said appliances, all you realistically need is a small genny.

the 12 v water system is so simple, it just backfeeds into a spigot. 40-60psi is no problem.




larger generators are typically not avail in an inverter style, thus cannot idle down to match the load. Generally speaking, 3000 watts is the typical inverter style gen avail within reasonable price.

large 5k and up simply draw loads of fuel and sing along at a set 3250 'ish' RPM to meet the 60hz frequency. inverter gens on the other hand do not.

outside recep for gen, slide the plate...

or a powerwall full of 18650 lithium cells and a quality inverter

YES A qualified home electrician is a must if you are not sure.

I just wanted to add that there are ways around the need for a larger generator

i installed a battery device that emits a ridiculously loud alarm when the power comes on. it just works by induction. amazon part. there is a pic up there by a poster. they do work well.

sorry for the long wind and gettin off topic slightly. oops

[panjumbie]

Originally Posted by Rusty

Could you give me the "jurisdictions" and "utilities" that don't allow an interlock on the panel cover. Also do you know of any cases where someone removed the panel cover and caused damage to anything while operating a portable generator.

I do agree that an interlock that is under the cover is better and real easy to put on.

Well, read the link at the bottom, all the way to the end. A hot topic among electricians. Typically disallowed in northern NJ, apparently. These have come up in informal discussion before and the understanding of the PE's I was talking with was that there were numerous locations that disallowed them.

In my mind any device that only works with the panel cover installed is unsatisfactory. Homeowners and even some lazy electricians leave covers off of panelboards all too often, either for a period while rewiring or for good.

I would be suspicious of any "third party" device, not manufactured by the panelboard/breaker manufacturer. The panelboards must be listed by UL or another listing agency, to be installed in compliance with the NEC, and quite likely (unless your jurisdiction has exempted the listing requirement) to be compliant in your jurisdiction. There is a significant question whether the panelboard listing, obtained by its manufacturer, is still valid (or would be considered to be valid by the manufacturer or the AHJ) if someone, licensed or not, modifies that panelboard with a third party device, particularly since the modification in this case requires drilling holes in the cover and putting a plastic wire tie around the circuit breakers (Yes, read the instructions provided!) The "kits" sold by the panelboard manufacturer itself would more likely be complaint with the listing.

Also note that the obtained listing for that product is for panelboards, not transfer switches, and the UL description for UL 67 specifically says it is not for transfer devices.

Additionally, if you check the listing restrictions on small portable generators, the article below says that the listing of the generator requires any transfer switch used with the generator to switch the neutral as well as the "hot" conductors. Circuit breaker interlocks can't do that. The NEC section on ground bonding limits most electrical systems to a single bond between the neutral and the safety ground, typically at or near the service disconnect. I think you'll find small portable generators have the neutral tied to the ground connections on the outlets (so that a ground fault can trip the breaker or GCFI) and probably also the frame of the generator. The NEC requires the portable generator ground to be tied to the building ground, and without a transfer switch that switches the neutral you will have a second bond between the neutral and the safety ground, which can cause stray currents in your system. If your portable generator has GCFI's, these stray currents may possibly cause tripping of the GCFI's. Since I don't have copies of the listing requirements (I do have a current copy of the NEC), I can't comment on the listing issues beyond what I've mentioned here.

Regarding people being injured or killed by backfeeds, Google "Lineman injuries from backfeeds". There are hundreds, maybe thousands, of links.

Beyond that, it is up to the owner and/or the electrician (or a Professional Engineer hired by the owner) to verify what your AHJ (Authority having Jurisdiction) and utility will permit. You might want to read your utilitiy's terms of service. They do have the right, (and under OSHA the requirement) to disconnect you if they find your installation presents a safety hazard to their employees.

I personally would not consider any "interlock" that would be inoperative if a cover were removed, or that required plastic cable ties around breakers to assure operation to be safe, but I'm not the AHJ or the utility safety engineer. Of course I (or anyone else) could file a request for a change of the NEC in the next (2020) edition of the code to add language to the code requiring the interlock not be defeated by removing a cover.

Do read the following: http://forums.mikeholt.com/showthread.php?t=152263

[StevenGilford]

Originally Posted by 8gv

Just don’t do the math on a cost/hour for your system so far!

Fingers crossed for multiple long outages to get value from it!

[Rusty]

Originally Posted by panjumbie

Well, read the link at the bottom, all the way to the end. A hot topic among electricians. Typically disallowed in northern NJ, apparently. These have come up in informal discussion before and the understanding of the PE's I was talking with was that there were numerous locations that disallowed them.

In my mind any device that only works with the panel cover installed is unsatisfactory. Homeowners and even some lazy electricians leave covers off of panelboards all too often, either for a period while rewiring or for good.

I would be suspicious of any "third party" device, not manufactured by the panelboard/breaker manufacturer. The panelboards must be listed by UL or another listing agency, to be installed in compliance with the NEC, and quite likely (unless your jurisdiction has exempted the listing requirement) to be compliant in your jurisdiction. There is a significant question whether the panelboard listing, obtained by its manufacturer, is still valid (or would be considered to be valid by the manufacturer or the AHJ) if someone, licensed or not, modifies that panelboard with a third party device, particularly since the modification in this case requires drilling holes in the cover and putting a plastic wire tie around the circuit breakers (Yes, read the instructions provided!) The "kits" sold by the panelboard manufacturer itself would more likely be complaint with the listing.

Also note that the obtained listing for that product is for panelboards, not transfer switches, and the UL description for UL 67 specifically says it is not for transfer devices.

Additionally, if you check the listing restrictions on small portable generators, the article below says that the listing of the generator requires any transfer switch used with the generator to switch the neutral as well as the "hot" conductors. Circuit breaker interlocks can't do that. The NEC section on ground bonding limits most electrical systems to a single bond between the neutral and the safety ground, typically at or near the service disconnect. I think you'll find small portable generators have the neutral tied to the ground connections on the outlets (so that a ground fault can trip the breaker or GCFI) and probably also the frame of the generator. The NEC requires the portable generator ground to be tied to the building ground, and without a transfer switch that switches the neutral you will have a second bond between the neutral and the safety ground, which can cause stray currents in your system. If your portable generator has GCFI's, these stray currents may possibly cause tripping of the GCFI's. Since I don't have copies of the listing requirements (I do have a current copy of the NEC), I can't comment on the listing issues beyond what I've mentioned here.

Regarding people being injured or killed by backfeeds, Google "Lineman injuries from backfeeds". There are hundreds, maybe thousands, of links.

Beyond that, it is up to the owner and/or the electrician (or a Professional Engineer hired by the owner) to verify what your AHJ (Authority having Jurisdiction) and utility will permit. You might want to read your utilitiy's terms of service. They do have the right, (and under OSHA the requirement) to disconnect you if they find your installation presents a safety hazard to their employees.

I personally would not consider any "interlock" that would be inoperative if a cover were removed, or that required plastic cable ties around breakers to assure operation to be safe, but I'm not the AHJ or the utility safety engineer. Of course I (or anyone else) could file a request for a change of the NEC in the next (2020) edition of the code to add language to the code requiring the interlock not be defeated by removing a cover.

Do read the following: http://forums.mikeholt.com/showthread.php?t=152263

Thank you for the info, a lot to digest but IMO and experience with interlocks they are safe and accepted by most code inspectors and utilities.

[Rusty]

Originally Posted by panjumbie

Additionally, if you check the listing restrictions on small portable generators, the article below says that the listing of the generator requires any transfer switch used with the generator to switch the neutral as well as the "hot" conductors. Circuit breaker interlocks can't do that. The NEC section on ground bonding limits most electrical systems to a single bond between the neutral and the safety ground, typically at or near the service disconnect. I think you'll find small portable generators have the neutral tied to the ground connections on the outlets (so that a ground fault can trip the breaker or GCFI) and probably also the frame of the generator. The NEC requires the portable generator ground to be tied to the building ground, and without a transfer switch that switches the neutral you will have a second bond between the neutral and the safety ground, which can cause stray currents in your system. If your portable generator has GCFI's, these stray currents may possibly cause tripping of the GCFI's. Since I don't have copies of the listing requirements (I do have a current copy of the NEC), I can't comment on the listing issues beyond what I've mentioned here.

Regarding people being injured or killed by backfeeds, Google "Lineman injuries from backfeeds". There are hundreds, maybe thousands, of links.

This is my generator setup and have been using it for 15 years..does it look OK?

7000 EXL Generac generator..neutral and ground are bonded.
Protran 6 circuit transfer switch which does not switch bonded neutral to floating neutral before going into circuit panel.
Seimens 200amp panel with neutral bonded to ground.

Would this pass inspection by the code cop?

[panjumbie]

Hi, I will not and cannot legally give you specific recommendations on your installation, only general information. My PE license is in NY, you are in NH. Furthermore, I'm retired and my license is set as "inactive". I'd have to pay to reactivate it. Finally, if I were legally able and willing to be your consultant, I'd have to take you on as a client.

In any event, the only people who can actually pass on your installation are the utility and the AHJ, Authority having Jurisdiction. usually your local electrical inspector or their managers.

As I explained before, the NEC is a recommendation, it has no legal standing on its own. Different jurisdictions have different laws. Some states have a state electrical code, which is most commonly based on one or another version of the NEC. New York, where I live, does not. Each locality has its own code and rules. The code in NYC is different than the one in Hempstead Village, where I live, and different again from the unincorporated areas of Hempstead Town.

And the inspection requirements are different. My village has an inspector, a Village employee. Many places use one or more private inspection/certification companies. The last time I looked, NYC had a self certification process for small projects, the contractor (licensed by the city) certified the work complied with the NYC electric code. But Con Ed also inspected services before making connections, particularly for underground services to residences, where Con Ed provided and owned the feeders running into your service and their employees made the final connection. Finally, for large businesses, their insurance company sent "loss prevention" inspectors from time to time. That was the case with my employer.

PE's can consult on code matters but the AHJ/Utility/Insurance inspector has the final word. If the owner feels strongly enough that the AHJ or utility is wrong, the owner can take them to court, where the PE may testify as an expert witness. Then the court decides. Needless to say, most such matters get settled before the court (either a judge or a jury) ends up having to rule.

Another issue, OSHA has adopted much of the NEC as a part of their rules, so if employees are protected by OSHA, their employer must comply with those parts of the code adopted by OSHA.

I will tell you that it appears your generator may tie the neutral to the safety ground internally, so you might have a compliance issue there, at least when the generator is plugged in. Whether the AHJ or utility cares, not for me to guess.

[Rusty]

Thank you for the well written response.

My generator does have an internal bonded-neutral but does not have any GFCI protected outlets which would trip once I plug it into the transfer switch. I could unbond the neutral in the generator but I use it at construction sites which could be dangerous to me and my help. I guess I could buy a generator where the neutral isn't bonded to the ground and use it just for my house but I don't think it is necessary. For the amount of time I use it to power my house I think I'll take a chance with this setup..

[panjumbie]

Originally Posted by Rusty

Thank you for the well written response.

My generator does have an internal bonded-neutral but does not have any GFCI protected outlets which would trip once I plug it into the transfer switch. I could unbond the neutral in the generator but I use it at construction sites which could be dangerous to me and my help. I guess I could buy a generator where the neutral isn't bonded to the ground and use it just for my house but I don't think it is necessary. For the amount of time I use it to power my house I think I'll take a chance with this setup..

I am not sure, and this is not professional consultation, but you may likely find that OSHA requires generators on construction sites to now have GCFI. At the minimum you should consider using portable cords that have GCFI included for all portable connections to the generator.

I suspect there have been more electrocutions on construction sites than from backfed utility services.

I would also think twice before modifying the wiring in the generator. The cure could be worse than the disease, particularly once the generator is unplugged from your house. If you modified the wiring, and then someone got hurt using the generator, even though it had nothing to do with the modification, you might be in a bad position.

One thing you might consider at home is to leave the generator unplugged from the transfer switch except when it is switched to generator. That does limit the possibility of issues from the parallel bonding to only when the generator is running. Since the generator is "small" and doesn't have GCFI's, you are less likely to have (non-regulatory) issues. Since I assume your transfer switch is manual, this doesn't add much effort to switching sources.

You should probably verify that the safety ground for the generator is at least as heavy as the neutral, because some or all of the neutral current is probably flowing through the safety ground when the generator is powering your house.