BD, How does the transfer box with the few breakers work?

B&D you posted a link to a generator transfer box that had the slots for 8 breakers. I am not familiar with these type of transfer setups. The ones we have on my farm and two of the houses switch the entire house/farm at the transformer. You then have to turn off enough stuff to match your generator wattage.

I assume that the set up you linked to would be setup like a sub panel??? Meaning that you would have the line supply coming through your normal main box to that box. Then the circuits/breakers going to the things you want to have your generator to run. So when you flip the transfer switch it disconnects the box from the mains and over to your generator supply.

I am interested in this because we need one of these type at my one son's house. A switch setup like we have at the farm would not work very well as his transform pole is not easily accessible. That is where the disconnects/transfers are on the other type setups I have. Plus he only needs a few circuits for his house only. The ones at the farm are for more circuits and watts than a small portable generator would handle.

Some questions that may seem silly:

1) I know the transfer box switches the two "hots and the neutral. How is the "earth" ground handled??? Do you need a separate ground stake just for this box???

2) The circuits that are being switched, they are feed through the transfer box only??? Then it handles which system supplies them???

I am just wanting to get it straight in my head how they work. I do have a certified electrical that inspects all of the work we do. I want to under stand it better so I can asked the questions that should be asked. If I do not understand it at all then we may miss something common. Assumed knowledge is usually where things get messed up. HE is good at looking all the stuff over but I don't want to have to redo a bunch of stuff after he would find we did it wrong.

GREAT questions JD, I compliment you, it shows you are interested and serious, so until Glen arrives I will answer them then see if he agrees or not, likely he will.


Some questions that may seem silly: PS there are NO SILLY QUESTIONS it shows your interest, yours are definite legitimate questions!!!!!!!!

QUESTION: "1) I know the transfer box switches the two "hots and the neutral."

a) NOOOOOOOOOOOOOO NOOOOOOOOOO for 120/240 volt single phase three wire, if the genset is configured as a NON seperately derived source,

YOU DO NOT I REPEAT DO NOT SWITCH THE NEUTRALS, ONLY THE TWO HOTS...Many people prefer that because it ONLY requires a Two Pole Transfer Switch !!!!!!!!!!!!!

b) HOWEVER, if the genset is configured as a seperately derived source YES YES you do have to switch the Neutral, but that requires a more expensive THREE POLE TRANSFER SWITCH. Most Ive seen ony use a two pole transfer BUT THATS NOT TO SAY YOU CANT USE A THREE NOOOOOOOOO PROBLEMMMMMM

QUESTION 1) How is the "earth" ground handled??? Do you need a separate ground stake just for this box???

ANSWER a) If the genset is configured a seperately derived source, similar to the utility transformer, the Neutral is earth grounded to a suitable GroundING Electrode such as driven into earth rod or rods (aka a made electrode)

b) If the genset is NOT configured as a seperately derived source (floating Neutral remember),,,,,,,,,,, And to preserve the concept of SINGLE POINT GROUNDING,,,,,,,,And to satisfy the requirement that all non current carrying conductive devices (just like a metal junction box) are grounded,,,,THE GENNYS CASE FRAME IS WIRED TO THE EQUIPMENT GROUNDING CONDUCTOR


QUESTION

2) The circuits that are being switched, they are feed through the transfer box only??? Then it handles which system supplies them???

ANSWER The Transfer switch switches (DUH lol) the LOAD from one or two sources: Either the UTILITY orrrrrrrrrrr THE GENSET. It has two inputs, Genset and Utility, then you select one or the other AND WHEN ONE IS SELECTED IT LOCKS OUT ANY POSSIBLE BACKFEED TO THE OTHER

Think of it as a DOUBLE POLE DOUBLE THROW DPDT SWITCH for a two pole system or a TRIPLE POLE DOUBLE THROW for a three pole system

SO THERE ARE YOUR ANSWERS JD, now if Glen agrees ???? NOTE he's currently practicing while Im retired lol

God Bless you again good questions, hope this helps you and all the other fine gents here

John T

Ol'John T knows as much or more than I do on the topic
The Reliance unit listed is a 200amp feed through transfer switch to be located outside. anywhere between the utility meter and the building service panel.
The four full size or eight half size breakers are just there to be handy if power is required right at the transfer switch for portable lights, kilowat frequency meter etc.
These feed through panels energize the existing building panel as if the utility service was being used. Just flip off a few breakers if a small gen set is being used.
Beats having a rats nest of extension cords running through a door or window. Keeps the gen set away from the building so CO is not drifting inside. Less noise too. Also keeps all the lights on which draw very little current. Not a fan of tripping in the dark because a four circuit transfer panel is being used.
The ground is never switched . There should be at least one ground rod bonded at every service,transfer panel or building entrance.
As most transfer switches are set up not to switch the neutral and use a floating neutral generator. The neutral should not have any contact with ground except at the power meter/1st service panel.

Yeppers, looks (as usual) like were on the same track. You used to have a link or picture of those cheap sliding lock outs that suffice as a sort of trasnsfer method when a breaker was being used to backfeed the main panel and if it was turned on the main breaker had to be necessarily turned off i.e. NO WAY BOTH COULD BE ON AT SAME TIME....to prevent backfeed....

Now you got me using the term FLOATING NEUTRAL also lol

Sorry we didnt meet again at New York Expo, maybe in 2 years I will make the pilgrimage

John T

There is an interlock that can go on a main panel. It prevents the main breaker and generator breaker being on at the same time.
It's usually cheeper that a stand alone transfer switch. And it is approved.

http://www.interlockkit.com/


Dusty

Sorry JD, I had to run and maybe missed one of your questions SILLY ME, MY BAD. I been mowing today plus coating my RV roof......

There is indeed a time when the gennys case/frame would be earth grounded......

If its configured as a "seperately derived source" (like a utility transformer basically) its Neutral would be connected to a Grounding Electrode (driven into earth rod or rods perhaps just as Neutral on a utility transformer)

The NON FLOATING Neutral would also be bonded to the gennys case/frame (just like transformer can) thereby the gennys case/frame is also earth grounded ........

Again, if its NOT a seperately derived source (Floating Neutral, only requires 2 pole xfer switch etc) then the gennys case frame needs to be wired to the Equipment GroundING Conductor (Remember thats NOT the same as the into earth GroundING Electrode).

I think Glen and I would agree any existing service entrance GroundiNG Electrode (say a driven rod or rods) would suffice for a gensets GroundING Electrode if one were required...If the genset only serves plug and cord connected equipment from onboard receptacles, a GroundING Electrode isnt even required, however

There, this and my other and Glens post OUGHT TO HAVE YOU COVERED, but if not hey were here for ya

John T

Thats what I was talkin about, thanks Dusty man, the AC Hat Man.........

John T

Then there is one that is a sub panel. The generator feeds that panel only, and anything you want to be able to run with the generator must be hooked to that panel. They will also work when the line power is on.

So you can see there are 3 or 4 different ways you can go.

Dusty

I've been using one of these InterLock Kit devices for years to attach my generator to the entire house. I had the mechanical interlock, breaker, and outside reverse-receptacle installed by an electrician.

I can power everything in the house except for the electric water heater. I can run the water heater if I turn off a few other items.

The whole system works great as an emergency power system. I have certain breakers marked with orange dots as those get shut off when running on emergency power.

From the moment the power goes off I can have the power back on in about 6-minutes.

B&D and John Thanks for your replies. I pretty much under stand how they work now.

I have another question for you. Another person posted a link to a steel sliding breaker block that would make it where you could not have the mains and dedicated generator breaker on at the same time. Would one of these be good enough???

The house in question is on city water and has all gas heat, cooking, and water heater. So we would be just talking about needing lights, frig, and the furnace fan in winter.

I do have a plug and box that has a MALE 220 volt plug mounted in it. ( weatherproof box too) I have not seem one like it around. But I was thinking about wiring it as the supply for the generator. This could be hard wired into a box on the side of the house. Then you would just need a short cord between this and the generator.

With the interlock setup the male ends would never be "hot" Which is why I never have used this box before.

I kind of like the sliding interlock deal in that it would be cheaper but even better you could change what you powered just by flipping different breakers. This way a smaller generator could be used.

Example: You have maybe a 5000 watt generator. You run your light and frig. Then after you go to bed your freezer and the frig.


Just thinking you would have a lot of flex ability with this over the dedicated circuit deal.

We have looked at the automatic systems. They just switch a few circuits. So you are stuck with just those things being powered.

The farm has a automatic system on a stand by Generator that can run everything. It is great but not cheap.

Where we are thinking about this setup having it switch automatically is not needed. If they are not home they do not need the things to switch over by themselves right now. Maybe later but trying to keep the cost down for now.

My friend and retired electrician the Dusty Man posted a link about them below and I know Glen has spoke well of them before I DONT HAVE ANY HEARTBURN WITH THEM but ya gotta realize its for using a branch circuit breaker in the main panelboard to backfeed the gensets output into your exisiting main box, WORKS FINE but not the flexibility nor the Cadillac method......Its something a tightwad like myself would do lol

Sure, cord and plugs and receptacles can indeed work fine, as you already state you're well aware of potential hazards and would avoid exposed energized male plugs (that almost sounds obscene lol this may get poofed JD) If the hot connectors can be the females and the non energized the male ends Id have less heartburn!!

Based on your fine posts and the info they provide, heres a sumamry of what I envision you have/need.........

1) A 120/240 genset settin somewhere that has had its Neutral to Frame Bond severed (maybe never even had that set up, i.e. Neutral was floating as Glen says???)

2) Its output has 4 wires, 2 Hots, Neutral (floating), Equipment Ground tied to case/frame.

3) Plugs n cords n receptacles (hope wired as above) with the 2 hots wired to a branch breaker in the main panel WITH AN INTERLOCK DISCUSSED ABOVE

4) The panels Equipment GroundING Conductor (bare/green) goes out via the cords to the gennys case/frame

5) The gennys Neutral wires to the panels Neutral Buss

THIS IS A 2 POLE TRANSFER SWITCH AND THE GENNY IS NOTTTTTTTT CONFIGURED AS A SEPERATELY DERIVED SOURCE It has a floating Neutral NOT bonded to case/frame yet its case/frame DOES NEED TIED TO THE BARE/GREEN EQUIPMENT GROUNDING CONDUCTOR

JD, go to the head of the class, depsite my earlier frustrations, I THINK YOURE GETTIN THIS Id never call you Billy Bob lol lol

PS my friend Glen isnt a fan of plugs n cords, he and I may feud over this set up lol

Feelin better now, think I have helped at least one person undersand all my rants n raves

John T

JohnT your are correct in that cost is an issue in this application. This is on the youngest son's house. So he has two kids and money is limited right now. Also the house in question is older and very well could be replaced not far down the road. So do not want to go hog wild to only have to redo it in a few years down the road.

I will enact the "Don't ask and do not tell" rule on how he has been doing it. LOL

This is why I wanted an economical way to correct his current way of doing it. Plus I have an extra 7500 watt gas generator that has electric start. It is one out of a RV so it does not have any wheels or anything. So it is just setting not being used. So I am thinking a little enclosure for weather protection plus a box and switch interlock set up, his wife could make it work safely if he was not home.

Thinking a small metal box/shed 20-30 feet away from the house. A good heavy cord hard wired to the generator. So all you would need to do would be open the enclosure. Hook the cord to the house box. Start the generator. Then go to the main breaker box and flip the main off and the generator breaker on. Interlock to make sure you do it correctly. Flip off all the breakers you don't need and you should be good to go.

I think it would be a cheap but safe setup and is what I am trying to help him get.

PS the generator is setup for propane. So Away from the house would allow me to tie it into the propane tank much easier.

OK guys pick this apart so I can see what I need to change. LOL

"I have another question for you. Another person posted a link to a steel sliding breaker block that would make it where you could not have the mains and dedicated generator breaker on at the same time. Would one of these be good enough???
"

PMFJI... prior to having my interlock installed I had an electrician check it out and he confirmed that it met all required codes for attachment of an emergency generator.

"Example: You have maybe a 5000 watt generator. You run your light and frig. Then after you go to bed your freezer and the frig.

Just thinking you would have a lot of flex ability with this over the dedicated circuit deal."

PMFJI again... This was my thinking EXACTLY. I have a 6500 watt generator and have no problem running lights, TV, fridge, freezer, UPS, computers, furnace. Basically everything except the hot water heater. In a crisis situation, I could flip the breakers for the other circuits and bring on the water heater by itself to get hot water.

I initially looked into the standard transfer box arrangement and they seemed like a bit of a nightmare to get installed and then of course you are limited to the circuits you pre-wire.

With the interlock, I flip the main the generator breakers and whaamo, the whole house has electricity.

I have been wanting to get a generator for years and kept putting it off. The compelling event was the big October storm a couple years ago where we were dark for 3+ days. I figured I would install the generator and then never need it again.

Funny thing is I have over 40 hours on the generator in just 2 years. We seem to have lot of 3-4 hour outages on clear blue sky days.

It certainly gives a lot of piece of mind on a cold winter night knowing that if the power goes out I can still keep things warm.

The interlock kit for about $150 is a ripoff. Genuine SqD is cheaper-- if they have one for your panel. I bought my SqD on eBay from a seller who must have been motivated as it was about half price. In addition to the interlock, the backfed breaker must be securely fastened into the panel. That prevents it from popping loose and having the live snap-on lugs flopping around exposed. The SqD genuine kit has that retainer. The $150 kit does not show it.

NOPE, NO NIT PICKING, sounds like a reasonable cost effective method to me JD. A few thoughts:

Since its a 7500 instead of a 4000 and out of an RV my best "guess" is its indeed 120/240 volt which is great as the smaller RV gensets are only 120 volt. Smaller RV's use a 120 volt 30 amp (2 pole 3 wire grounding) plug, while the big boys with 2 roof AC's use a 240 volt 50 amp (3 pole 4 wire grounding) plug that has both Hots, Neutral and Ground. One AC works on one 120 VAC leg, other AC the other.

Sorry, I just dont know if it has its Neutral floating or not (i.e. it has a connection to the case frame), but since youre only using a two pole (2 pole backfeed breaker) transfer method, the gennys Neutral needs to be unattached from its case/frame and then when you get to the house panel it, of course, wires to the panels Neutral Buss. The Equipment GroundING Conductor (bare/green) runs out of the panel and wires to the gennys case/frame.

Be sure the enclosure is ventilated enough for that air cooled genset. Many of those RV gensets already have a fan on one end which vents to the outside so Im sure you can get that figured out

GO FOR IT I SAY

John T

Sorry about the double post. Deleted.

Dusty

(quoted from post at 14:29:10 07/26/13) The interlock kit for about $150 is a ripoff. Genuine SqD is cheaper-- if they have one for your panel. I bought my SqD on eBay from a seller who must have been motivated as it was about half price. In addition to the interlock, the backfed breaker must be securely fastened into the panel. That prevents it from popping loose and having the live snap-on lugs flopping around exposed. The SqD genuine kit has that retainer. The $150 kit does not show it.

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Bus Driver, Thanks for posting that. I knew that there are better places to buy the Inter-Locks. The web site I posted illustrates very well how they work.
I should have said to go shopping for a better price.

Dusty

I installed a box similar to the one B&D recommends, based on his recommendation. It comes with two spare breakers installed, and spaces for additional ones. Right now those breakers are unused, and serve only to confuse anyone who tries to run the generator when I'm not home. But they would be very handy if I didn't already have an outside receptacle close to the disconnect. The spare circuits are on the house side of the box, so they are live whether you're on the grid or generator.

I looked at the lockout devices, but thought they were overpriced for a piece of sheet metal and a couple of screws. Plus I didn't want to sacrifice two slots in the breaker panel for the generator.

The Reliance transfer switches sold by the big box stores allow you to power a limited number of circuits, but not the whole house. This is a non-starter for me. I like the simplicity of the main disconnect transfer switch. It's very easy to install if you already have a separate main disconnect and the difference in cost with the other style doesn't amount to much. Now if you don't have separate main disconnect and main lug panels, installing a main disconnect transfer switch could be quite difficult.

check out reliancecontrols.com

I had a Kohler standby generator installed last year. It has 16 circuits and one of the circuits is for charging the battery. These were transferred to the transfer switch, 2 refrigerators, freezer, AC, Furnace, sump pump and light circuits. We now have two breaker boxes. We had a power outage last Oct when Sandy hit the east coast and the generator started automatically. Power was off for 26 hours. I stopped the generator when it had run for about 12 hours to check the oil. My neighbors were calling me asking how come my lights were on. Hal

It runs on natural gas. Hal

(quoted from post at 06:42:26 07/28/13) I had a Kohler standby generator installed last year. It has 16 circuits and one of the circuits is for charging the battery. These were transferred to the transfer switch, 2 refrigerators, freezer, AC, Furnace, sump pump and light circuits. We now have two breaker boxes. We had a power outage last Oct when Sandy hit the east coast and the generator started automatically. Power was off for 26 hours. I stopped the generator when it had run for about 12 hours to check the oil. My neighbors were calling me asking how come my lights were on. Hal

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Is that a copper water line intertwined with the romex? :shock:

The wires have been there 45 years and so has the copper pipe. That's the drain pipe from the laundry room. Hal

Your concern isnt totally unfounded in my opinion,here are my thoughts.

1) In the event that copper water line is actually one that leads underground (NOT just internal not in earth piping) I would consider it is a readily available GroundING Electrode and make it a part of an entire GroundiNG Electrode System, where it as well as other approved Grounding Electrodes, such as driven into the earth copper rod or rods (made electrodes) are all tied together and to which the incoming Neutral GrounDED Conductor is bonded (i.e. earth grounded)

2) In the event its NOT a Suitable GroundING Electrode (cant bond it to the driven rods and the Neutral) and one was concerned if a hot wire were to get shorted to it a shock hazard results, if it were connected to the panels Equipment Ground Buss by an Equipment GroundING Conductor (the bare/green wires) then if a live hot wire got shorted to the pipe, the Equipment GroundING Conductor would serve as a fault current return and trip the breaker thereby de energizing the live hot voltage hazard.

NOTE AND CAUTION a) I'm confident of Para 1 as NEC proper, I always used all readily available GroundING Electrodes such as buried utility pipes and driven rod or rods etc etc b) I'm confident the "THEORY" of Para 2 is correct, i.e. if the pipes bonded to the equipment ground and a short resulted such would trip the breaker......... c) HOWEVER I HAVE NO RECALL OR KNOW WHAT THE NEC WOULD SAY ABOUT MY PARA 2??? (if that pipe is NOT a suitable GroundING Electrode) I'm headed to Church and no time and besides I'm too lazy to look it up lol There are plenty of knowledgeable current practicians electricians onboard who are much more familair with the latest codes then myself SO NO WARRANTY ON PARA 2 (nor even 1 for that matter, its only my rusty code opinion)

See yall after Church

Ol John T and all