Polarity and Air conditioning

[alaska_av8r]

I installed an OceanBreeze 10,000 btu a/c unit on my boat.

I ran the air conditioning unit last week connected to shore power at a marina and it worked fine.

This week I attempted to power the boat with a Coleman Powermate 3000kw (3750 surge) portable generator. I made some short powercords that would allow me to connect from the portable generator to the shore power connections on my boat. The generator sits on my swim platform in a water proof enclosure.

I plugged in the power cords and started the generator. I had the shore power connect breaker selected off in the boat along with all A/C circuit breakers. The first thing I noticed was the red polarity light on my electrical panel. I knew I wired the shore power cords correctly but checked them to make sure, still the same result. I reversed the black and white wires and tried it again. The red polarity light still remained illuminated. So I went back to my original wiring feeling confident this was correct.

I flipped the breaker for my stove and the red polarity light went out, my stove also worked fine. I turned this breaker off and then flipped the breaker to power my air conditioning. I then turned the air conditioning on at the thermostat and it tripped the "shore power" circuit breaker. It did not trip the air conditioning circuit breaker or the circuit breakers on the generator. It just disconnected (tripped off) the circuit breaker used to apply shore power.

Two questions arise from this,
1. Why would the red polarity light be on when I know the cords were wired correctly but go out when a load is placed on the generator.

2. Why would it be tripping shore power and not the air conditioning circuit breaker if this 10,000 btu is too much for this portable generator. (I plan to call the manufacturer to check for the startup load tomorrow)

thanks
totally confused!!!

 

[Splat]

Re: Polarity and Air conditioning

Do you know if the generator you are using is a "true sine wave" (inverter type) generator?

Some generators that do not product a true sine wave or clean AC power will reek havoc with some electronic controls.

Your panel on your boat I'm not familiar with. the reverse polarity is it for AC (shore power) or DC from your batts?

Sounds like your electric panel may be PC controlled. If so on initial startup of the A/C unit, you could be getting voltage drop (brownout) and the panel is shutting down the circuit to protect motors and such. I'm just guessing here BTW.

 

[alaska_av8r]

Re: Polarity and Air conditioning

The boat is an older boat, 1987 Cruisers Inc 297. The generator is not a true sine wave and the polarity is for the shore power only. I am not sure what you mean by PC controlled but the electrical panel is a very simple panel, shore power comes in via two 30 amp supplies, shore power 1 and shore power 2, they individually go through their respective shore power on/off breakers, then to their own individual bus. So I end up with two separate AC busses each with appx 7 breakers.

 

[alaska_av8r]

Re: Polarity and Air conditioning

I was looking at my portable generator today and noticed it has a floating ground, I am not sure what that means or if it could be causing my problems. I still haven't gotten a straight answer on the start-up amp draw from oceanbreeze. I am going to have to call them again tomorrow. I had a hard time understanding the gentleman in Miami, but he kept saying the generator should run the Air and probably is faulty. I found out today that proforce (coleman) has declared bankruptcy so that is not good.

Another thing discovered was the outlet on the generator was unusual as far as voltage output, the "hot" had appx 55 volts and the "neutral" had appx 60 volts, is this normal for a generator?

Any marine electricians out there have any ideas?

 

[triumphrick]

Re: Polarity and Air conditioning

Obviously a 120v generator we are dealing with here I assume. Reading into the receptacle on the generator with a VOM, from the ground lug to the right side of the duplex (small lug) should read 120 v. from the ground lug to the left side of the duplex ( larger lug) should read 0v. Reading between the small and large lugs should read 120 v. Your shore power cables should have a white for neutral, green for ground and red or black for 120v. The above is standard for these generators and shore power cables. Check for an open or loose ground or an open or loose neutral. I think the hot side is good according to how the boats equipment is operating. I checked several 10k btu a/c units and they are only rated to pull 9 amps running. Don't know the surge (start) amps. Your generator is probably providing 20 amps maximum so you may be close on tolerances.....

 

[alaska_av8r]

Re: Polarity and Air conditioning

Thanks Rick I will look for a wiring issue, I thought that seemed strange. I'll post back what I find.

 

[hard-3]

Re: Polarity and Air conditioning

is your generator 120-240 or just 120 volt. i have a coleman 3500 that is 120-240 the duplex receptical on it is wired 120 volt to each plug. if you measure with a voltmeter from neutral to the hot on each plug you get 120 vt from hot to hot you get 240 vt. there is a seperate circuit breaker for each receptical half or it is also wired to the 20 amp - 240 volt twist lock receptical. look at the rating plate and see if it is 120-240 model you might have defective generator if you are only getting 60 vt . If output voltage is not correct try and take it to automotive electrical rebuilder and see if they can repair for you . Years ago I lived in Laurel ms. and used a company there to rebuild alternators and starters for off-shore equipment , but for life of me I can not remember who it was check yellow page under auto rebuilders

 

[alaska_av8r]

Re: Polarity and Air conditioning

I don't think it is 240 volt, I won't be able to check the plate on it until the morning, but here is the link to the unit that i have http://www.powermate.com/generators/product_detail.php?model=PM0103000&cat_id=3&w=59

 

[triumphrick]

Re: Polarity and Air conditioning

Nope that is not a 240v. Most of the lower wattage are only 120. Plus it says the receptacles provided are 5-20 a 120 v.

Still think that there is something going on inside the generator outlet, and not with the a/c or your power cord.

Were you able to test per my previous post?

 

[alaska_av8r]

Re: Polarity and Air conditioning

Okay today I was able to do some more troubleshooting, from the lug shaped like a "T" which I assume is the hot to the neutral 125 volts, from the "T" lug to the ground (green) 62 volts, from the neutral to the ground 64 volts.

I opened up the panel and found no loose wires, I removed the white wire and the green from the receptacle and did the same test as before to see if something was goofed up in the receptacle, the results were the same.

I opened up the end of the generator where the wires come out, nothing was loose in there, there is evidence this unit was dropped at some point, the connection block on the back of the generator was cracked (made of plastic) that shouldn't affect anything. There were two green wires going to the copper coils thru a plastic quick connect, the quick connect was partially melted, no wires exposed you could just tell it had gotten warm, that is about 12 inches from the exhaust....

That was all i was able to do today.

 

[triumphrick]

Re: Polarity and Air conditioning

Good that you had the 125 v on the hot lug. Now the tricky part is to see what that voltage does under a load. At some point, preferably closer to the a/c you need to make another reading while the unit is operating or trying to operate. That way you will have tested it completely through your wiring. If a brownout then the generator is suspect.

 

[alaska_av8r]

Re: Polarity and Air conditioning

thanks for all your help rick, is that normal for the neutral to ground to have voltage?....I would expect hot to neutral....and hot to ground to have voltage but.....neutral to ground?

I don't think I will be able to check voltage under load with the A/C it throws the shore power pretty quick....i could do it with the stove though....

 

[hard-3]

Re: Polarity and Air conditioning

try testing the generator with out the boat . get a couple of those hi power halogen lights and plug into the generator measure the voltage while you do this to see if it maintains voltage. the small generators have a problem maintaining voltage with current draw

 

[alaska_av8r]

Re: Polarity and Air conditioning

An update:

Well I finally got an answer as to what "floating neutral" meant. If you have a generator labeled "floating neutral" it means the neutral and ground are not bonded together. On a floating neutral it is better to not refer to the two legs as hot and neutral, they both are live until a load is applied. Instance, generator running but with no load if you take a voltmeter and go:

black to green - result is 60 volts
white to green - result is 60 volts
black to white - 120 volts

so that is why it was playing havoc with my shore power, my shore power saw the voltage on the neutral as reverse polarity.

Anyone else using "floating neutral" generators to power items on the boat?

 

[off the rock]

Re: Polarity and Air conditioning

I installed an OceanBreeze 10,000 btu a/c unit on my boat.

I ran the air conditioning unit last week connected to shore power at a marina and it worked fine.

This week I attempted to power the boat with a Coleman Powermate 3000kw (3750 surge) portable generator. I made some short powercords that would allow me to connect from the portable generator to the shore power connections on my boat. The generator sits on my swim platform in a water proof enclosure.

I plugged in the power cords and started the generator. I had the shore power connect breaker selected off in the boat along with all A/C circuit breakers. The first thing I noticed was the red polarity light on my electrical panel. I knew I wired the shore power cords correctly but checked them to make sure, still the same result. I reversed the black and white wires and tried it again. The red polarity light still remained illuminated. So I went back to my original wiring feeling confident this was correct.

I flipped the breaker for my stove and the red polarity light went out, my stove also worked fine. I turned this breaker off and then flipped the breaker to power my air conditioning. I then turned the air conditioning on at the thermostat and it tripped the "shore power" circuit breaker. It did not trip the air conditioning circuit breaker or the circuit breakers on the generator. It just disconnected (tripped off) the circuit breaker used to apply shore power.

Two questions arise from this,
1. Why would the red polarity light be on when I know the cords were wired correctly but go out when a load is placed on the generator.

2. Why would it be tripping shore power and not the air conditioning circuit breaker if this 10,000 btu is too much for this portable generator. (I plan to call the manufacturer to check for the startup load tomorrow)

thanks
totally confused!!!

Hello may i ask a question i have a AC problem

 

[UncleWillie]

Re: Polarity and Air conditioning

Hello may i ask a question i have a AC problem

Yes!, You are more than welcome to ask a question, but please do it HERE.

The purpose of this thread is to answer Alaska_av8r's question.

 

[UncleWillie]

Re: Polarity and Air conditioning

I installed an OceanBreeze 10,000 btu a/c unit on my boat...
2. Why would it be tripping shore power and not the air conditioning circuit breaker if this 10,000 btu is too much for this portable generator. (I plan to call the manufacturer to check for the startup load tomorrow)

In theory, a 10,000 BTU AC unit will require 2931 Watts (23.5 Amps@ 125 volts), assuming perfect conditions.
A 3000 watt generator is operating at its Max limit with just the AC running by itself.
A 5000+ generator may be recommended.

 

[kahuna123]

Re: Polarity and Air conditioning

Just a stupid question but aren't generators wired for two 120 volt ouputs 180 degrees out of phase?

 

[UncleWillie]

Re: Polarity and Air conditioning

Just a stupid question but aren't generators wired for two 120 volt outputs 180 degrees out of phase?

Yes! That is very common.
It is just the 240 volt output split into Two halves.

 

[kahuna123]

Re: Polarity and Air conditioning

I understand x marine electrician. My point is that you have to very careful feeding the panel that you do not cross phase certain things. You will have a big problem if you run the compressor on one phase and the water pump on the opposite. Or you can end up with problems like this. He said shore power "cords" which probably means two 30's. But wired correctly at the dock they would be on the same phase. Two feeds from a generator would be opposite. If mixed circuits (example water pump and compressor on 180 out of phase circuits) are being used you will see polarity problems.

And 20 bucks says this boat is not bonded.