Generator Transfer Panel

Yes you are missing something. You did not correctly specify what you wanted nor tell us what you got. Just from your description it appears you got a lightweight board for a lightweight job but think you can use it for a heavy weight job. Of course it could just be cheap and not even up to the rated specs whatever they might be.

It is an EmerGen 10-7500 watt panel. I don't think it's light, except in its construction. This is a load transfering transfer panel meaning it simply switches the load between to the two power sources (Gen or Line). My concerns are indeed valid. In the Line mode it feeds back to the circuit breaker in the main panel. In the Gen mode it feeds through it's own breaker ( in this case

20amp). My c> Yes you are missing something.

Out of curiousity, why didn't you simple purchase a line/generator switch from some outfit like Home Depot? Why choose a product with a lot of ineffective bells and gongs that really doesn't accomplish the primary safety goals?

Harry C.

Because they don't sell them here, unless your speaking of a double-throw switch. The cost and installation costs is prohibitive. Hindsite is always 20-20. Best residential equipment I have seen for my particular application is a Sqaure-D Gen Panel, which is a true sub-panel to the main loadcenter, but again costly. All the NEC requires is a positive lock than prevents simultaneously connecting backup power to utility power and is usually achieved by a latching device. The solution you proposed is really overkill for me, since I am only powering 6 essential circuits and the need to switch the entire distribution system is not needed. A lot of these so called generator products on the market are pure hype, marketing, and simply trying to instill fear. Now I can fully understand why so many people simply backfeed your homes. Killing the MAIN absolutely disconnects the utility side power. The real danger is inadvertently connecting both sources usually by human error. After all thats all a generator sub panel really is. Two Breakers one of which is feed from the main panel supplying the sub-panel, and the other breaker connected to the backup power source with the difference being an interlock preventing both from being on at the same time! Selected circuits are then relocated to the sub-panel. So all the hype and bull shit that the springs or contacts in a breaker can stick and create a hazard for the lineman, is nothing more than bullshit since that could concievably happen anyway regardless of what your using unless you kill the MAIN anyway.

Harry Conover wrote:

news:...

Is it possible that all the toggle switches carry is the load for the coils for the unit? I strongly doubt that they carry the full rated current load. I used to work for an OEM and our control circuits were generally #14 gauge or smaller for a reason. They were controls, not for powering anything. As for the construction, is there a UL-CSA label? If so then it has passed the requirements for the job established by the testing agencies. If there is no UL-CSA label then.......

Plastic pop out breakers..... What were you expecting? Bolt on's? For residential work stab in, pull out breakers are fine. You already admitted that a double pole double throw switch was expensive. (my personal choice for this situation)

C.E. has been around for a long time. (I have been in the trade for 30 + years) Their fusible pullout disconnects used to be the cheapest model on the market, completely legal just the least expensive. I have used 1000's of them.

As for the toggle switch rating, switches are rated for their ability to do work. Controls do not need much of an amp draw. I am sure the switch was chosen for the job and the price that they pay for it. Go to WW Grainger's and look at all the toggles available. Litterly tons of them by every manufacture in the world.

I suggest you complete your installation. Then test the installation, at least 5 times with different situations and see what happens. If your still concerned call the code official and or a licensened electrician for an inspection.

Do not forget the grounding issue with the generator. You can not just drive an ground rod at the location and call it good. I believe in (in your case)

3 pole disconnects. 2 hots and the neutral. Having a solidly made neutral with 2 sources of power can be a problem. If your neutral is not isolated from the power companies wiring (by a means of disconnect) when on the generator, you can and will in certain instances induce current and voltages back on the grid. Granted they are small, but if your line man is working on your transformer and gets zinged. I guarantee that you will be in court with the utility. I have been nailed by this in the past.

My view from the cheap seats.

Thanks for your comments however, the power companies neutrals are not isolated in ANY of these residential generator transfer panel solutions, or add-in generator sub panel solutions. In fact they are all bonded together at the main panel. And I have looked at them all (GenTran, EmerGen, Square-D, Cutler Hammer) Perhaps they are in utilizing what you are describing in the form of a master disconnect, but thats not required. As far as grounding the portable generator....the frame must be independently grounded. It's amazing you can talk to four different electricians and all of them will give you a different take. So which is the right way?

This is a type of human error that we cannot allow to happen. It's an easy mistake to make and it could kill somoene. I am not implying that you disagree with this; I am just noting it so that anyone who reads this thread understands the reason for the transfer panel.

Sorry but Killing the MAIN in a residential distribution panel is anything but a sure way of disconnecting the utility side power. You have to consider the failure modes in these device which are designed primarily to provide circuit breaker protection and not to function as a absolute line disconnect.

By contrast, a line/generator transfer switch is generally of the open-blade, knife switch conststruction, and provides absolute assurance that the line and the generator are never connected at the same time.

Anything else added is simply window dressing.

In many states, including here in Massachusetts, a safety device of this type is required by law.

Harry C.

If your main panel is squareD they offer an interlock that works with the main and a double pole breaker mounted in position 2,4. The kit is about $60 US.

The reason that some of us are so adamant about the back feeding is that we have seen what happens when the mistake is made. I was the first in EMT on the electrocution of a tree trimmer who was working to clear trees from power lines during an ice storm that extended from the southern states to Maine. We arrived to the shouts of the remainder of the crew begging us to get him down but we had to wait until the power company grounded out the line and declared it safe. The back feed was caused by a fault in a water heater that had one element supplied by a special meter and the other element supplied from the regular rate meter. The linemen cut down the offending homes service drop. Theirs was the very last home in the area to have power restored.

It is true that the commercially built transfer equipment is often constructed from breakers or contactors that can fail. Such a failure is far less likely than than the simple human error that it takes to close the breakers in the wrong order. The existence of the double male "suicide cord" is a separate issue. A home made set of office furniture in San Francisco was the starting point for a non fatal shock caused when a worker unplugged the wrong end of the "suicide cord" that supplied the furniture's built in outlets.

-- Tom

I don't believe that is completely correct. Many transfer switches are made up of breakers connected in one way or another. I have supplied many of them in equipment packages in the past as per specs for public works jobs. Also in industrial manufacturing plants it is done very often.

You're entirely correct about their being a wide variety in existing types of transfer switches. Some are capable of being computer controlled, while other involve the use of solid-state devices (a static transfer switch) for example. Still, each one I have seen or worked with was designed for an industrial environment, was very expensive, and provided a specialized, non-safety related function. Not one of these was designed for residental application in satisfaction of the required safety function.

To give an example --

WMATA (Washington Metro Area Transit Authority) employs a bank of Exide UPS systems to supply and filter power to critical applications at their control center, plus another bank of diesel generators to supply power on a sustained outage. Each UPS is, of course, equipped with a static transfer switch, which functions, in the event that the UPS inverter fails, to provide a direct, unfiltered connection of the load to utility power. Notwithstanding, when the emergency generators cut-in on extended loss of utility power, an electro-mechanical DPDT switch is unlatched and transfers the entire building load from utility feed to the generators. MBTA here in Boston employs a similar arrangement.

Contrast the above with a conventional residental or light industry application, in which utility power is fed to one side of a 3-postion (Generator-Off-Utility), manually operated switch with open blade construction, providing absolute assurance that no locally generated power can be fed back into the utility line. The switch also functions as a master power cut-off for the residence/facility when in the center position.

If someone wants to indulge themselves with an overly complex transfer panel or box, that is their option, provided that it provides the equivalent fail-safe technology found in every simple and inexpensive, open blade construction, power transfer switch. It's the responsible thing to do, since that lineman working on restoring electric service under absolutely horrific conditions has a life to live too!

Harry C.

Yes it can, but it has to be rated the same as your electrical service which is typically 100A or 200A. Harbor Freight Tools has a Cutler Hammer manual transfer switch in 100A for $199 and 200A for $299. These are huge and in raintight enclosures. They must be mounted adjacent to your main disconnect because they have no fuses or breakers inside of them. Needless to say, you will have to pull you meter to install this.

-- Mark Kent, WA

See below

Yes it can, HOWEVER, there are going to some issues. Trying not to omit the important steps you could do this. CHECK with the utility for their regulations. GET A PERMIT if required. Remove the meter and remove all the load wiring from the meter base to the main circuit breaker. Land these in the new 3 pole double throw service rated switch. Wire the load side to your main circuit breaker and the other set of lugs to the generator your going to use. Make sure that the grounding is done correctly at the generator. Now you can have 2 sources of power and isolation between them. It is manual but that should be ok and the way I would want it. The power company should be happy cause they have visible blade disconnection. A requirement here for islanding, ( that is what they call it here ) . This equipment is not small nor is it pretty.

You should look into the requirements for paralleling, just for fun. Now that gets crazy. I had a client that has a 900 kw gen set. The utility was going to offer credits and incentives for the conversion. The customer wanted to parallel and/or island as the condition warranted. The conversion of his main service was 220K. The additional controls was another

75K. The kicker was the county licensed his generator for standby only not prime power. Our local county has a regulation that when you hit 75 tons of pollution in a year you were considered a utility company. Needing an EPA impact study and all the controls and clean up stuff that is required. His generator would have made 75 tons of pollution every 7 days according to the manufacture.

Good luck, please let us know how this goes.