50 amp generator to a 30 amp transfer switch

[ResLur]

I have a 17,500 portable generator and have installed a 50 amp transfer switch, which has a 30 amp inlet. The cord to connect the generator to the transfer switch has a 50 amp male on one end (generator end) and a 30 amp female on the other. Is this okay? My electrician says it is.

 

[begreen]

I don't tink so Lucy. The wire gauge and plug should match the output. At 17,500 watts this sounds like it is designed to be direct wired, not plugged in. I would expect this to be on a 60 amp circuit. Or is the 17,500 watt a surge rating? Moving to the DIY forum to bring in some of the electricians.

What make and model generator?

 

[ResLur]

I don't tink so Lucy. The wire gauge and plug should match the output. At 17,500 watts this sounds like it is designed to be direct wired, not plugged in. I would expect this to be on a 60 amp circuit. Or is the 17,500 watt a surge rating? Moving to the DIY forum to bring in some of the electricians.

What make and model generator?

It is a generac generator

 

[begreen]

OK, so if this is the GP17500E portable they have several plugs on the unit for 120V, 120/240 - 30A, & 120/240 50A. Each has its own circuit breaker so you would be ok plugging from the 30 amp generator plug to the 50A transfer panel as long as the connecting cord wire gauge is #10 or higher for the 30A plug. The gauge will depend on the cord length. But that would only be using a small fraction of the power output. Why not connect with a 50A cord and plug?

 

[ResLur]

OK, so if this is the GP17500E portable they have several plugs on the unit for 120V, 120/240 - 30A, & 120/240 50A. Each has its own circuit breaker so you would be ok plugging from the 30 amp generator plug to the 50A transfer panel as long as the connecting cord wire gauge is #10 or higher for the 30A plug. The gauge will depend on the cord length. But that would only be using a small fraction of the power output. Why not connect with a 50A cord and plug?

The 50amp was difficult to find and I had a 30 amp. Now let me tell you want happened. It melted the ground (green) wire in the transfer switch.

 

[BrotherBart]

And that electrician said what about that?

 

[BrotherBart]

Since you are posting this all over the place, hopefully somebody has an answer. This isn't generators.com.

 

[begreen]

The 50amp was difficult to find and I had a 30 amp. Now let me tell you want happened. It melted the ground (green) wire in the transfer switch.

Agreed. The ground should not be carrying current. Get an electrician onboard before something else melts down.

 

[Jags]

If you are cooking the ground wire, that means you have a wiring mess down the line somewhere. Get a pro in there before you do permanent damage to something.

 

[ResLur]

Since you are posting this all over the place, hopefully somebody has an answer. This isn't generators.com.

Yes I posted on three sites. As you can imagine we are very stressed by this situation and are looking for a resolution as-soon-as-possible. I think we now have a resolution. By the way, I would like to thank everyone for their response. This forum is a wonderful tool and very much appreciated. Once again, thank you all.
Larry

 

[begreen]

What did you end up doing?

 

[ResLur]

Yes I posted on three sites. An you can imagine we are very stressed by this situation and are looking for a resolution as-soon-as-possible. I think we now have a resolution. By the way, I would like to thank everyone for their response. This forum is a wonderful tool an

What did you end up doing?

Thank for asking. There may have been an error regarding the wiring of the male 50amp plug, black and red were in the wrong positions. The diagram is very confusing and contradictory. We are thinking that the black should be placed on the left, white at the bottom, green at the top and red on the right. We are also replacing the 30 amp female plug on the cord with a 50 amp. We are replacing the #10 cord with a #8. We are replacing the 30amp male plug in the transfer switch with a 50 amp. We are also testing the generator to make certain it is producing the advertised amps, and not more. Yes, you guys have guessed it - we are now doing everything that we should have done in the first place. I think we got lucky here that there was not real damage. Finally, and once again, I would like to thank you guys for your assistance. You are wonderful people.

Larry

 

[begreen]

You should be using #6 stranded for a 50 amp plug. Be sure you know which terminal is for the ground (green) and which is for the neutral (white). Reversing the the red and black is fine. They are both hot legs. Better yet, have someone that understands this make up the cordset. It will be worth it if it saves some serious damage by mis-wiring.

 

[ResLur]

You should be using #6 stranded for a 50 amp plug. Be sure you know which terminal is for the ground (green) and which is for the neutral (white). Reversing the the red and black is fine. They are both hot legs. Better yet, have someone that understands this make up the cordset. It will be worth it if it saves some serious damage by mis-wiring.

Update, we just tested the generator 50 amp outlet. From green to hot on one-side 125v, from green to hot on the other 240v. We think this is the problem. By the way, the same for the 30 amp outlet.

Larry

 

[ResLur]

Update, we just tested the generator 50 amp outlet. From green to hot on one-side 125v, from green to hot on the other 240v. We think this is the problem. By the way, the same for the 30 amp outlet.

Larry

For me, the original question remains unanswered. If the generator is producing 120v on X and 240v on Y, why did the ground (green) wire in the transfer switch melt. Some how the additional current must have found it way to the transfer switch box. The solution becomes important as I move forward with the next attempt at connecting the generator to the main panel box.

Larry

 

[CaptSpiff]

Update, we just tested the generator 50 amp outlet. From green to hot on one-side 125v, from green to hot on the other 240v.

OK, electrical advice without a common diagram to reference is like shooting in the dark. I recommend you make up your own wiring diagram (hand drawn) starting with the generator represented as a "center tapped transformer". Google it for a drawing. Label the top of the winding hot (black), the center tap neutral (white), and the bottom hot (red). Sometimes in industrial generators the center tap neutral is independent of the Ground Lug (green), sometimes they are connected internally (ie white = green).

Now you'll measure 240v hot to hot, 120v each hot to neutral. This is not 3 phase, this is single phase, just like the utility delivers to your service panel in your house.

You measuring "green to hot on the other 240v" is a serious problem. Looking at a picture makes that clear. good luck.

 

[ResLur]

I do give my electrician credit for identifying the defect in the generator, which turned out to be the primary problem. The ground to Y was producing 240v. The new setup is as follows:

1. #6-4 cord/wire from generator to transfer switch
2. 50 amp male plug on one end of #6 wire/cord
3. 50 amp female on the other end of #6 wire/cord
4. 50 amp male on the transfer switch (Reliance pb50 plug). Rated for 12,500 watts

The new transfer switch is rated 15,000 watts.

Remember the primary goal - The 15.5 kw generator will serve as backup power during power outages in our area - which are common. I have a reliance transfer switch rated 15kw watts that will allow me to run various circuits within our home.

The new generator will be here 8/10/14 and the electrician will make all the necessary connections. I will let you guys know how it works out.

Once again, than you all for your comments. Thank guys are a great source of information.

Larry

Read more: http://www.doityourself.com/forum/e...tor-30-amp-transfer-switch.html#ixzz38tjdS5Rp

 

[ResLur]

Guys, my 50ft #6-4 cord arrive today. I had no idea it would be this large and heavy. But I think that I have what I need for the job. New generator should be here soon. I am very excited about connecting everything to see if it works.
Larry

 

[velvetfoot]

Excellent! #6-4, that does have to be heavy.

 

[ResLur]

Update: The 15,500 generator arrived today. I have my electrical permit and the electrician arrives Monday to connect all components. I have a very good feeling about this, why, because I have done my homework and I have a great electrician. (Mostly the research, including help from you guys.) The electrician came by Thursday for a planning meeting. I know what you are thinking, this is a small job - so why the pre-planning meeting? I am a firm believer that many conflicts with contractors could be avoid via pre-planning meetings. It gives you an opportunity to mentally walk through the process and to ensure that both are on the same page. My electrician was not very excited about this approach at first, but indicated afterward that it was time well spent. Based on our meeting, he prepared a materials list and both of us know what to expect. No surprises. (By the way, I fully expect to pay him for the preplanning meeting)

I will let you guys know how it turn out Tuesday.

Take care, and again, thank you all for your assistance, Lord knows I needed it.

Larry

Read more: http://www.doityourself.com/forum/e...tor-30-amp-transfer-switch.html#ixzz39vTcT3uf

 

[begreen]

Best wishes for a successful conclusion Larry. I'm glad you are getting a professional to finish the project.

 

[maple1]

Is this just for house backup? That's a lot of generator. Likely pretty thirsty too?

 

[ResLur]

Today's installation went well. The electricians did an outstanding job of installing all the components. When the installation was complete, the electrician used a voltage meter to test the new 15,500 generator. From 1) hot to hot - approximately 240 volts; 2) from neutral to hot (both) approximately 120 volts each; 3) from ground to hot - approximately 101 volts; 4) from ground to hot - approximately 161 volts. What are the changes that two different generators from the same company could be defective. We did not plug the new generator into the transfer switch. The matter is under discussion with the manufacture. Of course, Lowes will take the generator back, but I am so frustrated and tired with the process.

Regarding the above question - yes this is backup power for our home. We loose power often.

I am so disappointed.

Larry

 

[CaptSpiff]

OK, so a simple voltage test (with a high impedence voltmeter) is not enough.

Get 2 old 100W incandescent light bulbs, buy 2 construction sockets and connect them in series. Now you've got a 240v tester that can put a load on your voltage sources. Then repeat the same tests as you stated above. The bulbs will be normal bright across the hot-to-hot (240v). They'll be half bright across each hot-to-neutral. Then test each hot-to-ground, and you may get very dim or no light at all. If so then the Ground is not bonded to the Neutral of the Genset. This is not uncommon for industrial units.

If the 101v and 161v remain strong and steady, even with the lamp tester connected, then you've got bigger problems.

 

[maple1]

Do you really need a genny that big? That would amount to a monthly power bill close to or in the 4 figure range.

Sorry, guess that doesn't do much for the current problem. Hope you get things figured - the frustration must be off the chart. Keep us posted.