30A 110V Main Breaker Not Working

[boto]

We have two 30A 110V shore connections, number one (1) powers the main AC unit, number two (2) powers the AC outlets and battery charger; 2 works fine whether connected to shore or powered by the genset; 1 has recently been a problem. When connected to shore power 1 is a hit or miss; we've changed out the breaker, checked all wiring and replaced the boat's plug, 1 will sometimes work on shore power but not always, however, 1 always works while powered by the genset (we've ruled out the AC unit as the culprit).

I've exhausted my electrical know how and have puzzled the marine electrician we brought in; looking for any thoughts on this puzzle. As always appreciate your comments and insights.

[scallywag]

Is the A/C unit pulling to much power and trips the breaker? I had bells and whistles going off on the boat and found out it was a faulty ground. I put an ac checher on the plug and found out the problem. With an intermitant problem electricians have a problem finding the cause.
John

[Chief Engineer]

Have you tried reversing the cables in the pedestal ?

If the problem continues...it is probably on your boat.

If it doesn't it is in the pedestal

[colemj]

Originally Posted by Chief Engineer

Have you tried reversing the cables in the pedestal ?

If the problem continues...it is probably on your boat.

If it doesn't it is in the pedestal

Or the cord. You may have a bad connection in the connector or a kinked/cut wire in the cord.

Mark

[GordMay]

Has you checked the (Shore - Gen) Transfer Switch?

[boto]

Originally Posted by GordMay

Has you checked the (Shore - Gen) Transfer Switch?

Hey Gord, since the post we have done a lot of fiddling with the problem and thought we had it knocked after re-checking all connections and replacing a breaker. This past weekend the problem reared its head again and the issue seems to be related to the Shore-Gen switch. When we switched on the AC unit the fan worked fine, however as soon as the compressor kicked in there was some sparking followed by a steady "sizzle", needless to say we shut things down. Just wondering given your last comment if you had any further thought on the matter.

We are bringing in some more professional help on this one as it causes major concerns, however the more input the better.

thanks

[Ex-Calif]

Originally Posted by boto

This past weekend the problem reared its head again and the issue seems to be related to the Shore-Gen switch. When we switched on the AC unit the fan worked fine, however as soon as the compressor kicked in there was some sparking followed by a steady "sizzle", needless to say we shut things down. Just wondering given your last comment if you had any further thought on the matter.

Sparks and sizzle - Not good...

Where specifically was in sparking and sizzling? In the switch?

Sounds like a high resistance in the shore power circuit.

In any case whatever sizzled might need replacing.

[btrayfors]

Sounds like a bad shore-gen switch. Dirty contacts, bent/broken contacts, etc. causing a partial contact and high resistance. The A/C's fan only draws a little current, but compressors take a lot, especially when they're starting up. Obviously, the switch can't handle that amperage in it's current (deteriorated) state. What's more, problem would seem to be on the Shore contact side of the switch, since things work OK with the generator.

JMO,

Bill

[mobetah]

Hello Vicki & Ed,
I also have two 30A cables to my boat (one to the Air Conditioner and one for the house). This system was factory installed by Endeavour using a rotary Onan manual transfer switch. I have had similar problems in the past ...... my recomendations (for what they are worth) are as follows:

1. After disconecting both power cables and the battery cables to any inverters on board, bypass the manual transfer switch. You can do this removing both the black and white wires leading from the Air Conditoner breaker panel to the transfer swithch (remove them at the transfer switch) and reinstalling them on the same poles as(and along with) the white and black wires from the shore power to the transfer switch. by moving the white and black cables on the transfer switch (the black and white DO IT MIGHT BE A GOOD IDEA NOT TO START THE GENERATOR WHILE IT IS WIRED THIS WAY! MAY NOT BE A GOOD IDEA TO TURN THE INVERTER ON EITHER! After you have bypassed the transfer switch, reconnect the shore power cables try your air conditioner ....... If it works with no problems, then you probably have a bad transfer switch. REPLACE THE TRANSFER SWITCH! If you still have the same problem It's probably not the transfer switch however there is no guarentee that it's not the transfer switch along with some other problem.

2. If you still have the problem, you might try wiring a power cable direct to the transfer switch (reinstalling them on the same poles as (and along with) the white and black wires from the shore power to the transfer switch). Now try the system again, If it works now, the problem is either in your boat's power inlet or the wires between your boat's power inlet and the transfer switch. If you still have the problem it's probably not the boats plug or the wire between the plug and the transfer switch. But again, there is no guarentee that it's not one part a larger problem!

3. If that doen't solve the problem just keep bypassing things (like the wires from the transfer switch to the Air Conditioner panel) ..... eventually, You'll find the problem.

My money is on the transfer switch itself or the power inlet!

If it turns out to be the boat's power inlet simply replace it ........ If it turns out to be a rotary type trasfer switch, you might consider replacing the rotary type with two blue seas AC power source selector breaker panels (blue seas #8032). I did that on my boat and its works flawlessly. The rotary switches (at least the Onan type) are complicated and seem to go bad constantly (before changing over to the selector switches i replaced the rotary switch two or three times).... they are also expensive.

Good luck and I hope this is of some help
Bill A.

[boto]

mobetah/Bill A.

thanks for the suggestions, yours is the second time today I've ,receieved the same suggestions. I thought itm might have been the boats plug and or wiring from plug to panel. The plug actually had a good amount of corrosion as did the ends of the wires connecting to the plug from the panel. I've replaced the plug and stripped the wires back to clean sections while also checking the run to the panel so am 88.7% certain that is not the issue (99.9% is far too certain). Anyway will give the rerouting a shot and see how things pan out, appreciate the input.

As you are sometimes in Corpus, perhaps we'll run across you sometime as we hail from Kemah. Thanks again.

[boto]

Originally Posted by btrayfors

Sounds like a bad shore-gen switch. Dirty contacts, bent/broken contacts, etc. causing a partial contact and high resistance. The A/C's fan only draws a little current, but compressors take a lot, especially when they're starting up. Obviously, the switch can't handle that amperage in it's current (deteriorated) state. What's more, problem would seem to be on the Shore contact side of the switch, since things work OK with the generator.

JMO,

Bill

Bill, thanks for the input, will be checking the switch to see if that is the problem.