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Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15274
Experience:  Certified on Onan and Generac generators
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I have a generac 16,000 kw generator and when the power goes

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Good morning, I have a generac 16,000 kw generator and when the power goes off it suppose to transfer to the generator. It's doing that but when the power comes back on it do not get the message to to cut the generator off, in essence it does not transfer back to natural power it just keeps on running. So I am in the middle of getting a hurricane and I just use it manually.
JA: What's the make and model of the generator? And can you guesstimate how old it is?
Customer: I got it in 2006. I am looking for the model.
JA: Do you plan on doing the work yourself?
Customer: serial number(###) ###-#### No sir I doubt it would be something that I can do myself, but I like to trouble shoot any problem I have before I get help.
JA: Anything else we should know to help you best?
Customer: thats it, thsanks
Customer: replied 1 month ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call.
Customer: replied 1 month ago.
Let me know if you need more information, or send me the service offer(s) so we can proceed.
Customer: replied 1 month ago.
When will I get an answer please?

Hello, my name is ***** ***** I am going to assist you with this.

Which transfer switch do you have?

Customer: replied 28 days ago.
100 amp

I need to know the brand and model, not the size.

Customer: replied 25 days ago.
I have a generac generator
Customer: replied 25 days ago.
Cancel the phone call.
Customer: replied 25 days ago.
Guardian transfer box

The model number of your genset is(###) ###-####

I still need to know which series of transfer switch you have.

For now, I am going to assume it is an RTS series. If you find out otherwise, let me know.

Has the unit worked properly in the past, and this has just started, or is this a new install, or has there been any recent work done in the genset and/or transfer switch?

Customer: replied 24 days ago.
it is RTS and I have had it from 2006. No problems until now, actually no problems its just that when the city power goes off the generator comes on but when the city power comes back on the generator keeps running. It's not getting the message to shut down.
Customer: replied 24 days ago.
Why does it take a day for you to respond please? I been trying to get this sorted out but the response is very slow coming.
Customer: replied 24 days ago.

I am very sorry for the delays.

I have been on vacation for a week, and when I returned, I found that almost no generator questions had been responded to.

I am trying to work on a backlog of about 200 questions, and am doing the best I can.

I work 2 day jobs, and normally help on Just Answer in the evenings - and I still don't even have everything unpacked and cleaned up from my trip.

I am hoping to be back on my normal schedule after this weekend - but hopefully we will have yours done well before that.

There is only 1 thing that tells the genset that utility is back on - and that is a 240V feed to the genset from utility.

If the genset is in AUTO, and has the READY light lit while the power is on, it is getting a 240V signal from utility. If it weren't, it would be running all the time in AUTO.

The reason I asked about this being a new install, or if any work has been done recently, is because if the utility sensing wires are connected in the wrong place inside the transfer switch, what can happen is that the leads are sensing utility - but when utility fails, and the genset starts, it can actually read the output from the genset, instead of utility. It would think that it is seeing utility power, when it was really seeing genset power.

Lets start there.

Open the cover of the transfer switch, and remove the inside panel. Be careful, as there is 240V present in there.

In the bottom left corner of the TS, there is a 5-screw terminal strip with 4 wires attached to it. The left 2 wires are labeled N1 and N2, and lead to a fuse block with 2 fuses in it. These fuses are labeled F1 and F2. From the fuses up, the wires are labeled N1A and N2A.

From the fuses, the wires N1A and N2A need to go to the utility contactor.

There are 2 contactors, one right above the other. The top contactor is the utility contactor, and has 2 lugs on it.

The bottom contactor is the standby contactor, and has 4 lugs on it.

Check to make sure the N1A and N2A wires go to the top contactor - if they do not, they are in the wrong place.

Let me know what you find.

Customer: replied 24 days ago.
Good evening, nothing has ever been done to the generator. From 2006 it's been doing what it suppose too at all times. We have had several hurricanes here in the Bahamas and was not not until just recently I discovered that it keeps on running after the city power is back on.

Check the connections of the N1A and N2A wires to the contactor. Make sure the connections are clean and tight. Just remember that each of them carries 120V, and across them is 240V, so use electrically insulated tools.

If the connections are good, the control board is bad.

Customer: replied 24 days ago.
I think that is what the electrician said he believes it is. How expensive are the boards please?

That board will run about $325.

Customer: replied 24 days ago.

That's about average. Some are much higher than that.

Customer: replied 24 days ago.
Oh wow. I will look into then.


Thank you for using Just Answer, and please take a moment to rate my assistance, so I get credit for my time.

Customer: replied 24 days ago.
ok thanks

No problem.

To rate my performance, you must use the 'star chart', or I don't get compensated.

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