Transfer Switches - They're Nothing But Trouble Waiting to Happen

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OK, Lou and Ned, let me try this on you both.  You're pulling into a  campsite with your generator running and one or both air conditioners  on.  You want to hook up to shore power after you pull into your site  but you want to stay cool too.  Do you plug in to shore power after  shutting down the generator or do you let your transfer switch change  from generator to shore power after you shut down the generator?  Do you  do this with the air conditioners off?  Or do you make the switch from  generator to shore power manually (in which case the transfer switch is  not utilized?)
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I'd put one of the air conditioners on a separate plug and socket.  Turn it off (leaving the other running on the generator), go outside unplug it from the generator and use it's extension cord to plug it into the 20 amp shore power socket.

Come back inside, grab a cool one out of the fridge (running on propane, of course) and enjoy it under the still running A/C until the second A/C's head pressure bleeds down.

Now start the second A/C, shut down the first, shut down the genny, go outside and plug the main cord into the shore power socket.

Come back inside, grab another cool one and sit under the second A/C until the first is ready to come back on line.
 
Need explanation about the workings of a transfer switch.  Since it automatically changes from generator to shore power when plugging into shore power does it still have to do a transfer even if the generator is shut down before plugging in?  Even if you do  the shut down first and plug in next will a failed transfer switch still leave you with only one available power source?

I have been shutting down the gen before plugging in since a couple years ago when I didn't shut down the gen before plugging into a 20 amp outlet at the patio and it tripped the 20 amp house breaker.  Scared me and I haven't done that since.  Don't know what happened  but haven't found any thing damaged either at the house or in the MH yet after 2 years but don't want to take any chances.

Allen
 
Orick said:
The friendliest place on the web for anyone with an RV or an interest in RVing

::)
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I'll certainly 2nd that comment.  After some of the sourcastic remarks on other Forums this one is certainly a pleasure to read.  Maybe this is all due to John's work.

Allen
 
Wagonmaster2 said:
Need explanation about the workings of a transfer switch.  Since it automatically changes from generator to shore power when plugging into shore power does it still have to do a transfer even if the generator is shut down before plugging in?  Allen
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Actually Allen, the generator, when started, will cause a switch because it has preference in all most installations.  When the generator is stopped, the switch simply drops back to it's static or normal state and the shore power passes to the coach through the normally closed switch contacts.  Plugging into shore power while the generator in running will NOT cause the switch to change state.  Starting the generator while plugged into shore power will switch to gen power.

Your procedure of shutting off the generator before plugging into shore power is still good policy. 
 
I have been shutting down the gen before plugging in since a couple years ago when I didn't shut down the gen before plugging into a 20 amp outlet at the patio and it tripped the 20 amp house breaker.  Scared me and I haven't done that since.  Don't know what happened  but haven't found any thing damaged either at the house or in the MH yet after 2 years but don't want to take any chances.
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Allen, you're my kind of guy!  I don't like taking those kind of chances either.  Incidentally, what kind of transfer switch did you have when that happened?
 
LOU I am completely confused, pull plug, drink beer, switch something and drink beer, go in or out and do something else and drink another beer, this is crazy talk!
I would just sit down and drink the damn beer and forget all that switching stuff! :p

See what you started Rolf!
 
Rolf, It sounds like you think some of us here are too cavalier about switching power sources and that maybe we intentionally test and/or stress the capabilities/durability of our ATX switches.  I can assure you that, in spite of some of my flippant posts, nothing could be further from the truth. 

Have I occasionally screwed up and switched under load? YES
Has my ATX switch saved my bacon and continued to operate correctly? YES
Has my switch(s) always functioned correctly during power interruptions/recoveries? YES
Do I hope and expect that they will do so again in the future? YES

Am I worried that I somehow have shortened the life of the switch? NO
Am I paranoid about the possibility of the switch failing next time? anytime? NO
Should I (will I) test it now to ensure it still works? NO

I am a fairly careful and methodical guy by nature and will continue to use my ATX, as intended, without breaking into a cold sweat each time it functions.... or when it finally ceases to function.
 
Mark, just drink the beer and let the automatic transfer switch do the work :D
 
just drink the beer and let the automatic transfer switch do the work  ;)
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AMEN to that!

Speaking of that beer, don't use the containers that have pop top lids. They fail occasionally and leave you dying of thirst with an inaccessible beer. Seasoned beer drinkers know that long neck bottles with traditional caps are the best and most reliable. None of those fancy twist-off caps either - use the old reliable "church key".  8)

It never ceases to amaze me how RVers can turn the slightest thing into a  mountain of controversy.  Next will we hear that  "Real men don't use  transfer switches"?  ;)
 
 
[quote author=RV Roamer]
  Next will we hear that  "Real men don't use  transfer switches"?  ;) 
[/quote]

I use mine, but I don't inhale............... :D
 
RV Roamer said:
Speaking of that beer, don't use the containers that have pop top lids. They fail occasionally and leave you dying of thirst with an inaccessible beer. Seasoned beer drinkers know that long neck bottles with traditional caps are the best and most reliable. None of those fancy twist-off caps either - use the old reliable "church key".
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See?  That's why I like poorly lit state parks and other public CG's, especially when having a few beers.  Most private CG's park you a bit close together causing my black water tank to fill up too fast while watching my transfer switch do it's thing.  ;D ;D
 
rsalhus said:
Allen, you're my kind of guy!  I don't like taking those kind of chances either.  Incidentally, what kind of transfer switch did you have when that happened?
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Rolf-
I haven't had to change anything so its all original equipment.
Just to show you how much I know and understand about the electrical workings of these things we drive, I have no idea even where the transfer switch is let alone know what kind it is.  That was about to be my next question, on a 2004 Meridian 36G where would the switch be and what will it look like?

Allen
 
aka Porky said:
Actually Allen, the generator, when started, will cause a switch because it has preference in all most installations.  When the generator is stopped, the switch simply drops back to it's static or normal state and the shore power passes to the coach through the normally closed switch contacts.  Plugging into shore power while the generator in running will NOT cause the switch to change state.  Starting the generator while plugged into shore power will switch to gen power.

Your procedure of shutting off the generator before plugging into shore power is still good policy.
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Thank Porky -
I guess even being careful about shutting off the gen before plugging in could still result in a transfer switch locked into the gen position or even locked into the shore position when the cord is unplugged to start the gen then no gen power.  Either way it sounds really scary.

Allen
 
I have no idea even where the transfer switch is let alone know what kind it is.  That was about to be my next question, on a 2004 Meridian 36G where would the switch be and what will it look like?
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Well, I hope this isn't too controversial, but here's a picture of our transfer switch.  ???  It's the rectangular box in the upper middle of the picture.  In our coach, it's in the same basement compartment as the shore power cord.  I guess it could be just about any place in your coach. 

Now if you'll excuse me, I'm going to put my dunce cap on and go sit in the corner for awhile.  :-[
 

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Rolf,
You've stimulated a lot of fun as well as a healthy discussion of what a automatic transfer switch does and how it can fail. It's been a good ride!

And the dunce cap looks good on you!  ;)
 
Allen,
the transfer switch will be located wherever the shore cord and generator wiring come together. Usually that is where the shore cord enters the coach, or very close to it.
 
If you have one of the older Magnetek load centers the transfer switch is in a metal box mounted on it's rear.  Unbolt the load center (the whole box) and pull it forward out of the wall to access the switch.
 
rsalhus said:
Well, I hope this isn't too controversial, but here's a picture of our transfer switch.  ???  It's the rectangular box in the upper middle of the picture.  In our coach, it's in the same basement compartment as the shore power cord.  I guess it could be just about any place in your coach. 

Now if you'll excuse me, I'm going to put my dunce cap on and go sit in the corner for awhile.  :-[
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That is the model that went bad on mine.

No need for a dunce cap it is your coach do as you like.

wayne
 
OK, so I've come upon a good reason to resurrect this thread again. ::)  I've kind of implied this in the title of the thread but now I've got a post (below, in red) from Lou Schneider, who knows something about RVs, electricity, and transfer switches.  I want to put emphasis on the last sentence but just so I don't quote him out of context, here's his entire post to an Electrical Issue thread in Tech Talk (http://www.rvforum.net/SMF_forum/index.php?topic=35197.0).  Pay particular attention to the last sentence:

In theory, the transfer switch should be able to switch back and forth from generator to shore power.  In practice, it's not a good idea.

First, switching from generator to shore power while a load is drawing power is hard on the switch.  You'll create an arc across the switch contacts that can pit the contact surfaces and shorten their life.

Second, AC power switches from Positive to Negative and back again 60 times per second.  There's nothing to make the generator synchronize with shore power, so the instant the switch transfers you could have +120 volts on the shore power and -120 volts on the generator.  This will send a surge through everything that's turned on at that time, which will likewise shorten it's life.

In short, the best thing is not to transfer from shore power to the generator, or vice versa, while connected to shore power.

It all makes perfect sense to me, Lou, I certainly couldn't have said it better.  Now if any of you have a bone to pick with this, take it up with Lou.  I'm going to go sit in the corner again.  8)

 
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