Go Back   iRV2 Forums > MOTORHOME FORUMS > MH-General Discussions & Problems
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 10-29-2012, 06:19 PM   #1
Senior Member
Piker's Avatar
Join Date: May 2011
Posts: 1,126
Generator Circuit Breaker Help

Attached are a couple pics of the circuit breakers on our 7.5 kw onan generator. These are not from the service panel... they are right on the generator. Can someone please tell me why these two circuit breakers are so different? One large, the other small, but both rated at 30 amps... and no common trip. What is up with that? I'm trying to come up with a reason why there isn't a common trip, but I can't figure it out.

The generator outputs 120/240. There must be a couple relays in the junction box where the shore power and generator line converge prior to electricity being sent to the service panel. Obviously, when the generator turns on, there is one relay that disconnects the shore power. Then, depending on whether the shore power is 15amp, 30amp, or 50amp, there is another relay that either runs one leg of 120 down both sides of the service panel (15 or 30 amp) and that runs two separate legs of 120 down each respective side of the service panel (50 amp or generator). IF that control strategy is correct, I still can't see why a common trip breaker at the generator would be bad.

So you're probably wondering why I am so concerned about the common trip thing... Here's what I am doing: I am installing a 4 prong 50 amp rated receptacle next to the generator. This will serve two purposes. 1) so we can plug our house into the rv generator when the power goes out. We have a transfer switch wired to our service panel here in the house, and underground lines run out to the garage for a generator hook-up. 2) I want to be able to offer electrical power to our non-generator-owning friends when we are on the road and have to boondock.

The issue that I see is that the if I am to hook the house up to the generator, it needs to have a common trip breaker since there are a few appliances that will be running off of 240v. You would not want just one leg of a 120/240v appliance to drop - this could fry motors. You need to have a common trip for those appliances/motors.

At this point, I guess I can see why a common trip isn't necessary for the motorhome since everything runs off of 120v anyways... although if you trip one leg, and the relay breaks the remaining leg to both sides of the service panel, the appliance that originally tripped the first breaker will still be energized and you'll trip the second breaker any ways. Doesn't make sense to me. Might as well just have a common trip breaker right on the generator...???

I guess to make a long question short... does anyone see any problem with replacing these two breakers with a set of standard 30 amp common trip breakers?

Sorry that was so long winded... but I really want to understand how all this works.

Attached Thumbnails
Click image for larger version

Name:	DSC_0083.JPG
Views:	67
Size:	68.1 KB
ID:	28498   Click image for larger version

Name:	DSC_0084.JPG
Views:	58
Size:	104.2 KB
ID:	28499  


1994 Holiday Rambler Endeavor LE - Engine Rebuilt and Restoration in Process
Piker is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 10-30-2012, 11:11 AM   #2
Senior Member
Damon Owners Club
Workhorse Chassis Owner
Join Date: Mar 2009
Posts: 21,178
Stupid computer trashed my reply....

If those are both 120volt breakers I see no problem with a standard replacement and no reason for them to be different.

On a 30 amp RV, normally one of those breakers would be 20 amp and feed nothing except an air conditioner,, The rear one if you have 2.

On a 50 amp RV they should both be 30 One for each leg.

Home is where I park it!
wa8yxm is offline   Reply With Quote
Old 10-30-2012, 04:01 PM   #3
Senior Member
Piker's Avatar
Join Date: May 2011
Posts: 1,126
Thanks very much for confirming my suspicions. I picked up a little 30 amp breaker box today from Home Depot. I should have this all taken care of in an evening or two. Thanks again.

1994 Holiday Rambler Endeavor LE - Engine Rebuilt and Restoration in Process
Piker is offline   Reply With Quote


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

» Virginia Campgrounds

Reviews provided by

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 11:08 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.