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Old 07-31-2015, 10:42 PM   #1
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Electrical problems

I started to pull out the air conditioner out today because I couldn't get it to do anything despite it was supposed to be on the same circuit as the microwave which was working. I had cut the power, however, I had a power cord from the power pole so I thought I would plug in the positive, neutral, and ground in just to see if it would power up. It did, both the fan and compressor. So I then checked the trailer wiring that had been connected to the AC with a meter. The trailer was connected to the power pole. I tested the positive to ground and it showed 126 volts. I then touched the neutral wire which was energized. I then put the meter on neutral to ground and it showed 126 volts. I then checked the AS breaker box. I shocked to see that the neutral bar and the ground bar were not connected. I tested from those two and found 126 volts. Tested from positive to ground and got 126 volts. I cannot understand why the neutral is energized. When I check the power coming in from the power pole and it has a neutral, ground, and neutral. I can't understand how the neutral bar is energized. Please help!!!

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Old 08-01-2015, 06:39 AM   #2
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What Airstream? I am not understanding some of your terminology. But, grounds and neutrals should not have power on them. It sounds like one off the circuits you have going to one of those (maybe both) is hot....making all other circuits to that bar hot....and most likely the shell too. I would also suggest that the AC and microwave, high AMP units, be on separate circuits to keep loads a bit lighter. Have a Pro check it out.

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Old 08-01-2015, 07:18 AM   #3
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Has someone wired your "power pole" receptacle for 220? That would make both legs hot.
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Old 08-01-2015, 07:54 AM   #4
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what year and model do you have? in some trailers there is a switch in the cabinet over the sink that selects either the microwave or the air so you can't run both at once.
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Old 08-01-2015, 08:30 AM   #5
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If the micro was working the power to the AC was off as noted above.
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Old 08-01-2015, 09:01 AM   #6
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Electrical problems

You haven't told us if you have 30 or 50 amp service.

With 30 amp service where you connect the power cord to the RV will have 3 prongs; one hot, one neutral, one ground. In the breaker box will be two bus bars, one for nuetral, one for ground (also connected to the trailer chassis); and the hot wire connected to the circuit breaker bus.

With 50 amps there are 4 prongs, and two circuit breaker buses.

What do you get when you measure the voltage at the source? Where your trailer is plugged into?

How many prongs on the trailer?
How many prongs on the pole?
If they are different are you using an adapter?
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Old 08-02-2015, 12:26 PM   #7
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DO NOT connect the neutral bus to the ground bus in you breaker box!

Your RV is wired differently from your house. If you connect the neutral and ground busses together with the bonding screw, with the neutral hot as you describe, you would have energized the entre frame and shell with 120 volts. Major shock hazard as soon as you touch any metal part of the trailer.

If you have 30 amp service, and both the black (hot) and the white (neutral) wires are both reading 120 volts, then you are plugged into a 220 VAC outlet intended for a electric dryer or stove, not a 120 volt 30 amp RV outlet. Or the RV outlet was wired for 220 VAC, not 120 VAC. Unplug the trailer and check the outlet.

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Old 08-02-2015, 02:49 PM   #8
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Electrical problems

Thanks for all the replys!!! 1989 29 foot land yacht

The power pole plug is correct. I put it in and wired it. Single pole 30 and I put my meter on the box before I wired in the 30 amp plug. Checked continuity: box to ground rod, neutral to ground, neutral to grid. I have found the utility to be wrong before on their end. I checked the plug for volts. 126 from right blade hole with ground on the bottom of plug. Disconnect the cord at the trailer breaker box. Tested for volts. 126 from hot to nuetral and the same to ground. Nothing from ground to nuetral. So the problem is in the trailer. I will now test each 120 volt plug in the trailer for voltage just because I haven't. Do I need the check each circuit for lack of continuity by taking wires loose in the trailer breaker box. I would have to believe that a short between nuetral and hot would have thrown the breaker!!! Could the battery charger in the trailer feed back that much voltage on the nuetral side??? The AC has been running for hours in 100 plus heat wired direct from a 120 plug with 12/3 wire straight to AC. The trailer is new to me and I am new to trailerology. I do know AC and DC electricity. Just not a lot about dual applications yet.

The microwave did work on the same circuit.
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Old 08-02-2015, 03:29 PM   #9
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With the trailer unplugged, check for a direct short between the hot and neutral blades on the shore power cord plug. If you have a short, turn off all the breakers and check again. If you still have a short, then the problem is between the plug on the power cord and the main breaker. Check how the wiring is done inside the breaker box.

If the short is gone, turn on the main breaker inside the trailer and check again. If still no short, turn on the rest of the breakers one at a time until the short shows up again. Now you've isolated the bad circuit. You may find an outlet wired incorrectly.

Hope that helps.

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Old 08-02-2015, 03:49 PM   #10
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I'm having some trouble understanding, but sometimes receptacles are wired backwards and that will feed 120 v. into the common (what you call neutral; it is usually white) in some or every 120 circuit. I think that is what Chris is saying the post just before this. If the common and ground (bare or green) are tied together somewhere, then the ground will be hot too.

The receptacle you installed could have been done wrong. There's something about the standard trailer receptacles (120 v., 30 amp) that confuses electricians and the rest of us. When I wired one for our house, I kept trying to get it wrong, but used my meter on all the connections (and checked them all a couple of times) to make sure I got it right. I had trouble finding the proper receptacle (got it at a hardware store, a big hardware store; you probably won't find one at a big box store) and the person helping me had no idea what I was talking about.

If you bought this used, there is a strong possibility that someone did some wiring in the trailer and screwed up things. There are plenty of threads on the Forum telling about how their new-to-them trailer had messed up wiring.

Auto and trailer electric is always confusing because the ground is the vehicle and all those low voltage wires don't always use the same color codes, but your problem is with 120. It looks like your power company is sending voltage 5% too high. While a range of a few volts on either side of 120 is ok, 126 seems to be getting too high. This is not good for electronics. Your 12 v. circuits are probably reading 12.6 v. Products are available to bring your voltage to 120 v., but that would require some wiring at the breaker box and turning off all the power to do so.

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Old 08-02-2015, 04:03 PM   #11
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Sounds to me like you have an open neutral. Whereby any device connected to the hot leg and neutral will allow the voltage to "stand" across it. No current will flow since the circuit is open. But you will read voltage with the meter.
Turn the circuit breaker off for that particular circuit, then test for voltage on the neutral. If there is no voltage, the neutral is open. Meaning it is not connected to the neutral buss.
As stated earlier the neutral should NOT be bonded in the coach. The panel in the coach is considered a sub panel where there is no bonding.

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