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

[Just Lou]

I'm not sure I agree with any of the arguments, pro or con, for transfer switches.
 
  I sure can't understand the cost complaint.  The best transfer switch available on the internet costs about as much as dinner and drinks for two.  The average switch lasts somewhat more than 24 hours (maybe 24 years), dinner and drinks do not......
 
  IMHO the transfer switch (barring any confusing explanations from JFD) actually makes it easier to diagnose power connection problems. 
 
  I have three transfer switches in my coach.  One for gen/shore power, one for switching to inverter and one for the second air conditioner when using the generator.  The coach is 13 years old and I have never had a switch failure.
 
  I'm currently considering the design of an automatic power cord connection (much like the mid-air refueling boom and receptacle) so I won't ever have to leave the drivers seat to connect to any power source.

 

[carson]

Hee Hee, Lou ;D

  I think you need another transfer switch...that may have prevented your front-end vibration problem.

It's amazing what one can learn on this forum.

  Of course, I am just razzing you. Take care...

Carson FL



 

 

[rsalhus]

I'm currently considering the design of an automatic power cord connection (much like the mid-air reufueling boom and receptacle) so I won't ever have to leave the drivers seat to connect to any power source. 

I'm thinking about designing a treadmill for an RV that will come down from a sidewall at the push of a button.  Just think how convenient that would be on cold or rainy days.  And if you had a transfer switch in your rig, you could select either shore power or the generator to power it without leaving the RV.  8)

 

[Gary RV_Wizard]

I think Rolf is at least somewhat justified in poking fun at us for what some might call "extreme convenience". I'm not giving mine up, though.

 

[Ned]

An RV is "extreme convenience" compared to hiking with a knapsack and tent on your back.  I'm not giving mine up either

 

[Tony_Alberta]

  I sure can't understand the cost complaint.  The best transfer switch  available on the internet costs about as much as dinner and drinks for  two.  The average switch lasts somewhat more than 24 hours (maybe 24  years), dinner and drinks do not......

Hehehehe    Unless, of course, events progress to where 18 years worth of child support payments are required. 

 

[rsalhus]

My intention was never to convince anyone to give up the use of their transfer switches.  But if I can convince one person to question whether they would feel just a little safer to switch power sources manually than to use the transfer switch to do it for them automatically, then I'd feel a whole lot better.  So far, I haven't found that one person yet but it's still early.  :'( :

 

[Just Lou]

...if I can convince one person to question whether they would feel just a little safer to switch power sources manually than to use the transfer switch to do it for them automatically, then I'd feel a whole lot better. 

Can't say as I agree with (or understand) this logic either.

 

[Ned]

It doesn't get much safer than turn on the generator and the transfer switch does the rest.  What is unsafe about that?

 

[rsalhus]

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?)

 

[Just Lou]

I pull into the campground and hook everything up. 

BTW - I (and you both) have to go outside to do this.

NOTHING happens to the power source or transfer switch until I complete my hookups, wash my hands, fix my drink, shut down the air conditioner(s), shut down the generator (now the switch transfers) and enjoy my drink.  The temperature in the coach very seldom rises to a dangerous level while this is going on.  If it does, I add extra ice cubes to my drink and turn the air conditioners back on.

I realiize that's a very unsafe practice, but I like living on the edge.

 

[rsalhus]

I realiize that's a very unsafe practice, but I like living on the edge.

AHA!  So you do think about it!  Thanks Lou, I feel a lot better now. 

 

[Just Lou]

AHA!  So you do think about it!  Thanks Lou, I feel a lot better now. 

LOL Rolf, I'm afraid you totally misread my attempt at humor.  Actually, I never give the process a conscious thought.


I feel the need to amend the above comment.  I meant to convey the message that I do not fret or worry about the performance, failure, cost or convenience of the transfer switch.  I do, however, try to follow a sensible and safe procedure when switching power.  There isn't much I can do about truly automatic transfer switching between shore/generator/inverter.  My generator does not have auto start.

 

[rsalhus]

Actually, I never give the process a conscious thought.

OK, Lou, whatever you say.  But I still feel better even if you only think about it unconsciously.  :

 

[Jammer]

Ten things that will never make Jammer mad because they cannot happen in Jammer's rig:

10) Electric step won't retract.
9) Slideout won't deploy.
8) Electric awning won't go out because the moisture sensor is a little damp.
7) Auto-leveling system wakes up Jammer by re-leveling coach in the middle of the night.
6) Out-of-state dealer won't honor extended warranty.
5) Air ride system won't air up.
4) Toad battery is dead because Jammer didn't pull the IOD fuse.
3) EMS won't connect shore power to coach for reasons unclear even to Jammer.
2) Generator won't start.
1) Transfer switch won't transfer.

To be sure we are all entitled to our tastes and our styles of travel.

Now, putting my engineering hat on for a moment, there is absolutely no reason why a transfer switch should fail simply because it had to operate under load.

Back when I had cows I fed silage and had a 10HP motor on the silo unloader.  It was turned on and off by a relay.  A cheap, chinese relay, that I got from the cheapest place on the internet that sells industrial controls.  I think I paid $40 for it.  That motor drew maybe 150 amps when it started up and 60 amps when it was running.  Once in a while the unloader would jam and the relay would have to shut the thing off while it was stalled and drawing 150 amps or whatever.

I ran it for two years before I sold my cows and it never failed or stuck even once.

You could make a transfer switch out of two relays like that.  They make a mechanical interlock for them so that it is impossible for two adjacent relays to close at once.  People use the interlocks for hoist controls and other situations where it's going to be ugly if both side close at once.  If the places that make transfer switches can't do better than that, well, shame on them.

 

[Ned]

The easiest way would be to plug in the shore power.  There is no load on the shore power cable at that point and the transfer switch would keep the RV powered from the generator.  Then turn off the A/C and any other heavy loads.  Let the generator idle for a few minutes to cool down, then shut it off.  Power transfers to shore, turn the A/C back on and you're done.

I can't remember the last time we used the generator and roof A/C on the road, so it's a moot point for me.

 

[rsalhus]

Then turn off the A/C and any other heavy loads.  Let the generator idle for a few minutes to cool down, then shut it off.

And do you ever think about what MIGHT happen or what COULD happen if you turned off the generator without turning the A/C off first?  If you do, and if you think it mght be safer to turn the A/C off first, then that is what I am trying to get people to think about. 

 

[catblaster]

Our AC and most others have a 3 to 5 min "delay on break" timer that keeps them from trying to start back up under high head pressure. Transfer switch isn't fast enough to over come the delay timer so the switch doesn't have to connect with the AC load. Ever thought of a manual transfer switch, cannot engage both sources at the same time, also most automatic transfers have a mechanical lockout keeping them from engaging both sources....note I said most.

 

[Gary RV_Wizard]

I think about it, Rolf.  And I normally do a procedure such as Lou outlined. Plug in, turn off a/c, shut down generator and turn a/c back on.  I know my transfer switch can probably handle the switch under a big load - or at least should have been designed for that - but I don't like to put equipment under unnecessary stress. I figure it's bound to last longer if I'm kind to it.

 

[Mark R.]

Sounds like I am the only one here that has a transfer switch but will never have exposure to stuck relays, my switch is manual, shore-off-generator.

It is not necessary to shut of any AC powered equipment prior to turning switch to off from gen or shore but I do to reduce contact arcing under load, I always shut off Air Conditioners before turning on power from gen or shore.

Rolf you started this thread with how lazy are we or something like that, well I fried my 2500 watt inverter on my boat five years in a row by plugging in before shutting down the inverter, not proud of it but you know "POO happens".