Source Selector for A/C Power

[Joe Cannarozzi]

Recently, we started getting only 1 leg of 110A/C when running the generator. Just by chance a tap on the control pannel brought it to life, however after a few minutes of opporation a electrical component smell occured.

I swung open the control pannel and found this:

The Power selector for 110A/c [Generator/off/Shore] was getting so hot it was melting the black tape that it is wrapped in to cover the terminals.The plastic housing of the switch was also almost too hot to the touch. Looking further I started hearing slight crackling and I discovered one of the large black power cables that either go to or come out of it had pulled loose from the terminal it was supposto be clamped in. It was making contact by just laying on it and ocaisionally arking.

I shut everything down reinstalled the cable but still only get 1 leg of 110A/C from the generater. I checked shore power and everything checked out good no problems there. Something odd I noticed is that the terminal that was loose and arking has become very rusty while the other 8 are like shiney new, could arking over a long period of time cause this? I cleaned it up to where I concidered it satisfactory but the problem still percisted.

Now for the dumb questions;

Seems to me I need to find out 1 of 2 things- If I,m getting power from both legs from the gen. to the switch and or if current is flowing through the switch correctly. What electrical tool is required to check this?

I cant understand how the 2nd leg worked while loose and arking and now that its reinstalled it wont. Could it be because it was arking off the other leg that happened to be right next to it explaining the heat build up due to the remaining leg carrying twice the current that it was designed to do?

Ill call an electrician if I have to but I would like to first find out if its the Gen. or the switch. WHAT KIND OF A ELECTRICAL TESTER AM I LOOKING FOR?

[truk4u]

Joe,
I'm shooting in the dark here, does the gen have a single dual breaker or two breakers, one for each leg? Could the breaker be fried? I just use a multimeter for testing the juice.

[Joe Cannarozzi]

Mabye, where would I find that at the generator? We have a Universal but its really a Kuboda.

[jello_jeep]

Well, I don't have such a swirch on my bus, so not sure just how its wired. But if the terminal going into the switch is loose and it was arcing, I would assume the switch is fried and needs replacement.

I am not sure if this switch you speak of is like a perko switch, where the current actually goes through the switch, or just controls a relay or another type of controller.

If it goes through the switch, each leg would have its own terminal, and that would surely explain why you only get one phase of the gen.

Good luck!

[Joe Cannarozzi]

Yes current does go through and it would be too easy if all we have to do is the switch. Im out to purchase a meter.

There are 9 leads hooked to this switch and im assuming 3 are from shore, 3 are from Gen. and 3 go to the main breaker box.

Do you have an explination for the corrosion on the terminal that was loose?

[jello_jeep]

Ok, if we know the juice goes through it, and the terminal is loose in the housing, you should replace it regardless. As you saw and felt, it can easily cause a fire. Lucky you were around and smelled it and shut the system down.!!

Good luck..

[Joe Cannarozzi]

Here is a picture of that switch. I checked it with a tester and sure enough there is 2 hot going in on Gen. and only 1 hot comming out. On shore power 2 hot in 2 out.
My Bus 061.jpg
I think the good Lord was watching. If I would not have pulled the inverter remote from the control pannel to have it repaired, thus creating a opening in that pannel for the smell of that burnt switch/loose connection to escape I dont know if I would have smelt it.I also believe that mabye the opening and closing of this pannel for all the repairs weve made over these first 9 months might have tugged it loose,then arking ruined the switch. That lead is the short one as you swing the pannel open its first to get taught. There is 6 more leads connected to the back side of the switch, just like this side, that I couldnt get a shot of where the culprit lies.

Just for future referance: Is there breakers on the generator itself? Ive never seen any. They would probbably have to be in the box at the rear with the hour meter and switches?

[jello_jeep]

Joe I can't answer that for sure, I just drove home from Lake Havasu City AZ, and stored the bus there so I can't just jump out and look.

If memory serves me right, there is a gen disconnect along with all the other electrical goodies in my second bay, but this is all converter stuff, so probably different on yours.

It would stand to reason that a 20KW gen would have breakers somewhere though!

Glad you found your problem, and didn't go up in smoke!!

[kmuller]

Joe - I know there is a tendency in the group to self diagnose and repair, but I have to tell you, in my opinion your situation really needs to be inspected by a QUALIFIED tech. The risks are simply to high.

[garyde]

If you have not done so already, verify you have 240 volt coming from the Generator with a Volt Meter such as Knapp, Ideal, Fluke, etc.
After you have confirmed the voltage is 240 volt to the switch from the Generator, you will know if the Generator circuit breaker is tripped.
If you have 240 volt to the switch, then go ahead and test for 240 volt on the outgoing side of the switch (load out).
If you do not have Load out 240 volt, then there is something wrong with the switch.
You can also test the switch with power off with a continuity tester, testing one terminal at a time (line side to load side)
Usually when termials heat up to the point you describe, the switch has burned up internally.
Gary