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Jason
Jason, Service Technician
Category: Electrical
Satisfied Customers: 4284
Experience:  Over 20 years of experience in all types of installations, troubleshooting, and repairs.
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I have a Model 030235 Briggs and Stratton Generator (5550 WATTS/8550

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I have a Model 030235 Briggs and Stratton Generator (5550 WATTS/8550 STARTING WATTS). I have connected it to my 5th wheel RV using one of the 120V connections. When I turn on the air conditioner (110 V air cond), even with nothing else running, it will run for about 8 seconds. That is how long my surge protector in the RV, which also has under/over voltage protection) will monitor the power prior to disconnecting it. I am pretty certain it is not the start up that is kicking it off, because it stays online for the 8 seconds. Also, no circuit breakers are popping. The AC circuit breaker in the RV is 20 AMP. The 110 receptacles on the generator are 30 AMP. I measured the voltage at the AC CB prior to turning on the AC and it is approx. 115 VAC. I measured it after turning on the AC (prior to the surge protector disconnecting the power) and it fluctuates between ~ 99 and 101 VAC. My surge protector is designed to disconnect it when it is below 102 for 8 seconds. So I know the problem is with the volts decreasing as the generator takes on the load. My question is, can I increase the voltage coming from the generator...or should I even do that? The generator does have a 110V/30A receptacle, but I will have to get an adapter. And I don't know if that will even fix the problem.

Jason :

Hello. Welcome to Just Answer.

Jason :

Have you tried taking a voltage reading at the generator outlet that the air conditioner is plugged in to? You mentioned taking a reading at the AC circuit breaker, and the meter was showing 99 - 101 volts. But was that reading right at the generator?

Customer:

No. The reading was at the Air Cond CB inside the RV. I will hook up the gen again and see what the reading is at the gen while the AC is running.

Jason :

Sounds good. Please post the reading here at your convenience.

Customer:

Jason, here we go.

Customer:

Sorry...hit enter too soon. when I taek the generator out of the picture and hook the RV up to my shop power (110, 20 AMP) the readings are as follows (Readings taken at AC CB in CB panel inside RV). AC off 114V. AC on 108 volts. AC runs fine, does not kick off even when I add some lights, etc to the equation. I hooked th gen back up and here are the readings. 1. (readings at AC CB in CB panel in RV). AC off 115V. AC on 100V- surge protector disconnects power after about 8 seconds. 2. (readings at generator). AC off 118V. AC on 108V - surge protector disconnects..... So basically, I am reading about an 8 volt drop between the generator and the AC CB in the RV. Although the gen is putting out plenty, the surge protector is reading a low enough voltage to interrupt the supply. Any ideas?

Jason :

108 is a little low, even if it would be a sufficient voltage for your surge protector. It may not be good for the air conditioner.

Jason :

If you increase the size of the wire from the generator to the RV panel, you can probably eliminate the 8 volt drop.

Jason :

I would start with that, using a larger gauge cord.

Jason :

If the cord is substantially long, a shorter one could help as well.

Customer:

OK...I will give that a shot and get right back with you...about 10 minutes.

Jason :

OK, I'll keep an eye out for you.

Customer:

Jason, used the heavy duty 10' cord that came with the gen. The readings at the gen and the CB panel were so close that it isn't worth noting. the lowest reading I had was at the CB with the AC on...105V. The surge protector did not disconnect the supply, so all seems good. However, If I wanted to get this gen a ways away from me while camping, what guage extension should I use? The one I had been using (and losing voltage) is a 100', heavy duty construction cord (12AWG).

Jason :

You would need to go up at least one size, but two would be even better. I don't know if this helps or not, but I bought #6 rubber cord about a week ago. So there are large sizes available. Do you know the amperage rating that is stamped on the air conditioner's data plate? If so, I can try to plug the values into a voltage drop calculator and suggest a suitable cord size for you.

Customer:

Get right back with you

Customer:

couldn't fid the amperage on unit...only said maximum 20 CB to be used. Looked it up online (Dometic Duo-Therm Quick Cool Model # XXXXX). Closest I could get to a match is 59516.731). It says a total of 15 amps....sounds about right if the breaker is 20..

Jason :

Yes, I agree. I already plugged that amperage into the voltage drop calculator, and if the generator output stayed at 120 (right at the generator outlet), the load end voltage would be 116.4. That's a drop of 3.6 volts, which is exactly 3%. This would be with a #10 copper cord. That's the maximum recommended allowable voltage drop. However, your generator's output voltage isn't 120. It's lower than that. So, if you can find #8 rubber cord (local electrical supply houses should have it), that would be better.

Jason :

Just think of it this way, the longer you want the cord, the larger gauge you should buy to prevent excessive voltage drop.

Customer:

Sounds Good. Thanks much Jason....it just occurred to me that this is the second time you have assisted me. Can't recall my previous question though...take care.

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