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Posted By: tonyc Emergency generator - 06/15/04 12:31 PM
Has anyone heard of problems using emergency generators back fed thru a 30 amp 4 wire dryer plug using the neutral ground and all.

I have heard rumors of heating up ground wires and have no clue what they are talking about.

We got pummeled by a Hurricane out here in Va. Beach last year and backup generators are the hottest thing going everybody wants a plug in the garage now.
Posted By: Roger Re: Emergency generator - 06/15/04 12:48 PM
Tony,
Quote
Has anyone heard of problems using emergency generators back fed thru a 30 amp 4 wire dryer plug using the neutral ground and all.

This is illegal regardless of any problem rumors.

Roger
Posted By: Bill Addiss Re: Emergency generator - 06/15/04 03:42 PM
Tony,

The big problem with what you propose it that it's too easy for something to go wrong.

Here's a few sentences I found on this subject. I'm sure if you search you can find much more: (bold is mine)
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WARNING: Improper connections to a building's electrical system can allow the generators electrical current backfeed into the utility lines. Backfed power may electrocute utility workers or other individuals who may contact the lines during a power outage. Consult with the utility company or a qualified electrician.

Improper connections to a building's electrical system can allow electrical current from the utility company to backfeed into the generator when power is restored. This utility backfed power may cause the generator to explode, burn or cause fires in the building's electical system.
from this page
Posted By: Radar Re: Emergency generator - 06/15/04 06:44 PM
I'll second both points made by Bill above. From much personal experience parallelling large generators in a past life (Navy), you DO NOT want to have a generator online but no way to synchronize when the utility power comes on.

I believe I've seen moderatly (Profitably) priced residential grade power transfer equipment sold in kit form which is just made for this purpose. Safest way to go.

As an electrician, at my house, I might think I can get away with an outlet arrangement as you described, but I know to go yank the utility meter before I hooked up. Then there is the question of which loads to connect, etc. The generator won't run everything. This is not necessarily as easy as the home owner presumes it is.

What about grounding issues?

Just way toooo many things to go wrong. Too much risk and liability, as you have no control over the home owners actions after you're gone.

Radar
Posted By: pauluk Re: Emergency generator - 06/15/04 08:24 PM
Quote
you DO NOT want to have a generator online but no way to synchronize when the utility power comes on.

Allow me to relate a little story which happened at a British telecommunications facility some years ago.

In replacing the control modules for the generator set, somebody somehow managed to miswire the synchronizing circuitry and clearly didn't check it before putting it in service.

When they came to parallel two generators, the sync circuitry did it's job in matching speed and locking the gensets together. Unfortunately, they were synchronized out-of-phase when the connection was made.

I understand they were retrieving engine parts out of the roof for some time...... [Linked Image]
Posted By: tonyc Re: Emergency generator - 06/15/04 08:35 PM
I guess I should have told you that most everyone out here turns the main breaker off in the panel before they do all this unfortunately there are knuckle heads who don't and who think they can power the whole house. Now this is not a 100% guarantee of not powering up the grid. I feel like I am the only one who has seen this done. Home Depot and Lowes were selling these things including male dryer plugs and 10-3 SO by the truck load during the last Hurricane and I know that most of these folks were not taking the time to install transfer switches. And we all know that a 6kw portable generator ain't the cleanest power to be had soooo back to the original question even if you do use a transfer switch has anybody had or heard of any issues with heating up the neutrals or any weird stuff going on.
Posted By: dougwells Re: Emergency generator - 06/16/04 12:17 AM
This is no wonder people get the wrong ideas about how to hook up generators http://www.princessauto.com/_osn.cf...57&PageSearch=ALL&CurrentPage=17

Just Click on the more info on the receptacals

[This message has been edited by dougwells (edited 06-15-2004).]

[This message has been edited by dougwells (edited 06-15-2004).]
Posted By: srscott Re: Emergency generator - 06/16/04 01:51 AM
Square D for sure and I'm sure a few others manufacture just what you're looking for. A small 2 or 4 circuit sub panel is fed from the main and the outside generator plug, it's an either or proposition (the panel is fed by utility or geneator)and has to be done manually, but it's legal and safe. How can any of us trust anyone during a power outage to be methodical, etc. This does the job, the geneartor can be wheeled back there and you can sleep at night.
Posted By: tonyc Re: Emergency generator - 06/16/04 12:03 PM
Problem is in most cases they are used so in frequent most people don't want to get off the loot to put a transfer switch in.

The other thing is they want more control over what they can run and not run instead of the transfer panel delegating that to them.


A new issue is, is that store bought generators play havoc on the electronics we have in our homes now ie microwaves, TV you name it.

Out here people were getting real desperate after the last hurricane and the prediction is another rough year.
Posted By: pauluk Re: Emergency generator - 06/16/04 12:12 PM
From Doug's link:
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4-WIRE DRYER/RANGE PLUG ENDS
8005774
$ 89.99
Is this for real? Ninety bucks???!!!! [Linked Image]
Posted By: sabrown Re: Emergency generator - 06/16/04 01:00 PM
I did not notice that this was brought up, but I have a concern about the cable from the generator. When connecting up a generator (after the required transfer switch) the male end must be located on the wall of the location served and the female end on the end of the cord coming from the generator. Using a dryer receptacle would be an absolute NO.

Besides the problem of killing a utility worker if there is no transfer switch, plugging a generator into a dryer receptacle will submit the user of the generator to unacceptable hazards. The power coming from the generator will be energizing the exposed male end of the plug which is never acceptable, thus the end of the cord must be female where you would be attaching to the building. I would refer to NEC 230.62(A) and 445.14 if someone wanted to argue there life or the life of a loved one (or maybe not so loved). Plugging the thing in the wall does not make it unaccessible or guarded.

I personally use and require twistlock types or pin and sleeve on top of this to avoid inadvertant removal of the power supply or partial disconnect possibly exposing energized parts.

Shane
Posted By: tonyc Re: Emergency generator - 06/16/04 01:10 PM
Hey Paul,

It's Canada
Posted By: classicsat Re: Emergency generator - 06/16/04 04:37 PM
The picture shows twist lock fittings, although I have see at least male straigt blade 14-50 caps (what is actually used for dryers and ranges), either the familar Hubbels (used in the portable Miller welder demo trailer taken to farm expositions and the like), and a right angle Eagle. I have aslo seen people splice an acutal dryer/stove cord assembly onto a chunk of whatever cable.
Posted By: pauluk Re: Emergency generator - 06/16/04 05:54 PM
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Hey Paul,
It's Canada
Ah, didn't notice the Ontario bit on the page before. [Linked Image]

I make that about U.S. $65. Still seems very expensive for a twist-lock receptacle, though. How much would this run in the U.S.A.?

Good point about the added hazard of using a plug end on the generator lead to connect to the range/dryer outlet.

I've seen people in this country try a similar approach with a regular British plug inserted into any convenient outlet.
Posted By: SolarPowered Re: Emergency generator - 04/08/05 10:23 PM
There's something that seems obvious to me that I never see mentioned on these threads. Square D makes a mechanical interlock for their QO panels that allows you to interlock the normal main breaker with second, back-fed main breaker in the upper right-hand location. The interlock assures that only one of the mains can be "on" at any time. (Both can be "off," however.)

I understand that this is UL listed for feeding a generator into the panel.

This appears to be the obvious way to go--a few bucks for the interlock (I think it's $10-$20), one breaker, and you're good to go.

So why aren't people doing this? Is there some problem with this approach that I'm not seeing?
Posted By: renosteinke Re: Emergency generator - 04/08/05 11:15 PM
I assume that there will be a transfer switch used....and that the generator is used for something else, or stored elsewhere, until needed.
I assume that is why you want to connect the generator with a flexible cord.

The product you are looking for is called a "power inlet." Besides being available from electrical parts houses, they are often found at RV supply houses. They have a "male" plug end recessed in, and covered with a plate. This is installed on a deep box attached to the building. When the time comes, open the lid and insert the female end of the power cord.
These are available in various configurations. For all I know, boating suppliers have them as well.

BUT DONT LEAVE OUT THE TRANSFER SWITCH !!
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