Check your trailer wiring, and here is why. I had a complaint on one RV that for no reason, just out of the blue would pop a breaker on one circuit or another. But it was allways on a circuit that had a significant load. A microwave, AC, TV or invertor. Finally got to the breaker box and the ***** that installed the power cord did NOT tighten the neutral wire down solid. Without the neutral the 125V plugs could have the poential of 240 on them. The neutral was burned badly and had to be trimmed off and moved to a different lug for the connection. After that no more mysterious breaker poping problems. The only piece of equipment that got damaged was a clock radio. The rest somehow survived untill the breaker poped.

 

Now that's interesting. I would have never thought to check that, but you may be on to something. I have had an trip on the AC from time to time and never found anything wrong that should have caused it. Then again, after thinking about it, it usually does it after the generator kicks over. This is a fairly new trailer and I would be surprised if that would be the case, but anything is possible. It's worth investigating. Appreciate the guidence.

 

Doesn't hurt to check the connections, especially on a new coach.

My brand new trailer kept tripping breakers when I ran the furnace. The problem turned out to be a loose connection at the load center.

 

I just got a new example today. The park I live in, Destiny of Dallas, has had the road and fence rebuilt over the last year behind the complex due to new apartments being built. As a result the fence had to be relocated as the city was wideing the road. New fence posts went up today and they cut the neutral wire in the cable to one of the sites jut a few slots down from me. He lost a microwave, two televisions, an invertor and every 120V light that was on at that time.

His hookup is a normal 240V 50amp 4 pin plug.

Who is going to pay for this screw up, the park? The city? The fence company? The guys at the park is likely going to pay for his damage. The park will bill the city for reimbursments, the city will likey go to the fence company and the fence company will likely blame the park for not telling them that there are buried cables in there, even tho the electricians had put those nice bright little flags everywhere that said "Danger, High Voltage cables" that allways get ignored.

 

I admit that I do not know everything there is to know about electricity. But, I cannot figure out how cutting a neutral wire will cause a 120v circuit to become 240v. If you cut the neutral wire to any circuit, you simple loose that circuit.

In the example above when the neutral was cut they would have had to short the other 120v leg to the neutral wire to cause a problem. If just breaking the neutral could cause a 120v circuit to become 240v, it could happen when pulling the plug and the neutral disconnects first. I have never heard of that happening and I do not believe it could happen since there is no connection between the other leg and the neutral wire. This would require two problems at the same time such as the neutral being cut and the other leg is shorted to the neutral.

Daniel

 

The reason it happens is this. All of the circuits on a house wiring or 50amp RV have the incoming line divided in the breaker box to evenly load the 240V line. Half on one side, half on the other. In the middle is one neutral for all the circuits. If you kill the nuetral and you have live load on either side of the nuetral the opposing loads will take their neutral load to the other side whick will equal 240V via an equipment or load jumper. Two opposite phase 120V hooked togehter equals 240V without a nuetral. One side of that to a neutral is 120V. With the AC ON on one side and an invertor ON on the other side with both using the same nuetral not connected to line serves as an equipment jumper and provides 240V on any outlet at that point.

Its real easy to find out. Just simply hook your RV into a standard 240V 50 amp outlet (provided its a 50amp RV), turn on everything and pull the nuetral lead only. Count how many seconds you get before things pop and smoke. I think you can get to O......

Belive me, its not the first time I have seen this happen, even to a house.

Dont take my word for it, try it. Just be ready to warm up that check book too when, you do. Or better yet, call my park and ask them how fast that happens and how much it costs.

And I just found out about an hour ago that the neutral cable wasnt all that was cut here. They also put a couple hundred phone lines out as well. Needless to say the fence isnt getting finished by this weekend

Oh, and if your pulling the plug out without turning off the supply first, your just asking for a big surge to bite your equipment in your RV. Even bite you. At the very least it causes burn and arc marks on your plug on your cord and the plug in the box. ALLWAYS turn OFF the supply before plugging in or unplugging your RV

 

Tim;

I agree it is not a good idea to insert or pull a plug with a load on the circuit. However I have never seen it do any damage other than arcing of the plug to the receptacle.

What you are saying is if I wired two light bulbs from one of my 240v receptacles putting one on each leg and then disconnected the neutral it would blow the bulbs. I do not believe this would occur because the load on the lines is still equal to 240v. If the bulbs were of different wattage the larger bulb would be limited to the current flow of the lesser bulb and would burn dimmer. With these two bulbs of equal size there would be no current flow through the neutral and disconnecting it would change nothing.

Daniel

 

Daniel, try this for an explanation. Take two lights and wire the leg from one light to the other --O----O--. Take the wires off a double pole breaker and wire to the two other legs of the light bulbs. The bulbs are now on one 240 volt circuit. Now take the wire between the two lights and and connect it to neutral, --O---+---O--. Now each bulb is on a 110 circuit, so you now have two 110 volt circuits. I believe this is what Tim was trying to say.

 

Here's a very crude drawing of a 120/240 VAC power system using a center-tapped transformer with the center tap being the neutral leg. The voltage across the outside legs (L1 to L2) is 240 VAC, but the voltage from either outside leg to neutral (L1 to N, L2 to N) is 120 VAC as shown. Now, if the N leg is lifted (broken), the 2 loads shown will be in series across a 240 VAC circuit. This could happen if N is lifted anywhere between the bonding strip at the RV's power distribution panel where the individual circuit neutral legs are joined together (i.e., the loose neutral case) and the transformer.

Does this help?

Rusty

 

Dan239. All things being equal, if all you used was two lightbulbs of equal wattage you would be right. But use a light bulb and an air conditioner in the same manner and that light bulb would pop instantly. The reason is the load and resistance is not equal. The AC would provide a better, lower resistance path to the light bulb and the bulb would see a 240V line and then BANG!

Even tho the designers of load center TRY make a balanced load from on side to another, its never perfect and they cant take into account what you plug into it. Only provide plugs for you. The known loads that are close to balance is the refridgerator, AC, invertor and water heater. Those are only balanced when they are all ON. The rest of the plugs are split up and purposely seperated because of location. That way its harder to bring two appliances together that may have the potential of shorting together with a 240V surprise! Then depending on whats ON and whats not will determine what kind of damage will happen when you loose a neutral.

 

Tim;

I will agree that if a small bulb is on one leg with a heavy load, such as a 120v A/C, is on the other leg and both are on, if you lose the neutral it will probably blow the bulb as if it were a fuse. However, I do not believe the bulb will see 240v because the voltage will remain split between the two loads. The bulb will blow because of amperage overload. I do not believe that the bulb and the A/C will both see 240v. In electrical theory the only way they could see 240v each is if you had a 480v source.

Daniel

 

Nope. It sees 240. The reason is again, two 120V lines on either side of neutral that are oppsite phase equals 240. The 240 does not need a neutral. The two loads married together on opposite 120V poles equals 240V across each other. Its real easy to verify with a volt meter.

Like I said, I have seen it. Done it. Been there. Have the scars to prove it.
And again, dont take my word for it. Go and try it out for yourself. The proof is in the pudding, as they say!

 

I agree there is 240v across both loads in series. Surely you do not think there is 240v across each load. Any loads in series will split the voltage according to the resistance of each.

Based on what you are saying, each load would read 240v on a meter, it would read 480v across both loads. That would be very difficult when you only have 240v available.

The only way for each load to see 240v is if the are wired in parallel.

If we go back to my example of two 120v light bulbs of equal size wired in series in a 240 volt circuit. Are saying that a meter will read 240v across each bulb?

 

Yes and no. It will read 240 across both loads. If you lift the lead at the beginning of either end, or in the middle it will read 240V. The reason?, no neutral. But your running two 120V bulbs in series so no problem, providing they are the same. But the AC requires a LOT more amps to run than say a 40 WATT bulb. The bulb will not provide enough of a circuit to run the AC and since there is now 240V across the load, the bulb looses. It is 120--+--120 equals 240. The positive is on both sides and both neutrals are tied together in the middle completing the 240V circuit. The middle is SUPPOSED to be the neutral instead of being a jumper, but without the neutral connect to the supply, its 240V volts ACROSS the ENTIRE load. Without equal resistance on the equipment thats connected across the load, one looses. Kinda like a fuse. But if its a TV and a AC, both 120 items hooked in a series to a 240V line, the TV will blow, the loads are uneven.

Why dont you just go try it??

 

I agree the load that is less will lose. If we talk about the 40W bulb in series with the A/C with no neutral the bulb will lose just as if it were a fuse. However, your saying it will blow because of voltage is not correct. Just like a fuse it will blow because of amperage being more than it can handle. All fuses I have ever dealt with blow on amperage not voltage.

We are obviously not going to agree on this so I am dropping it.

Daniel