Automatic vs. Manual Transfer Switch - I need your opinion!!!

[grantgoold]

Folks, my automatic switch burned up and the circuit board is more expensive than to purchase a new switch. I rarely use the genset for power but was thinking that I could get a nice manual switch and not have to worry so much about the circuit boards and all the fancy stuff. No real problem to flip the switch once or twice a year!

I can get a nice switch box for both gen and shoreline for about $125 (60 amp).  The automatic switch from IOTA is about $200.00


You thougths and suggestions?

Thanks

Grant

[Lin]

We have a separate receptacle for shore and generator.  To switch over, we just move the plug from the panel from one to the other.  You can't get more manual then that.  We also have an Iota transfer switch that switches from shore/generator to the inverter.  I think the Iota 50 amp transfer switches can be had on Ebay for less than $125.

[TomC]

My main box has 4 50 amp circuit breakers-2 for land line, and 2 for the generator.  I also have a sheet metal slider that only allows 2 circuit breakers at a time to be flipped.  Since I have a tie bar on the two generator circuit breakers, there is no way to have both on at the same time.  Easy, simple and all parts bought from Home Depot.  Good Luck, TomC

[JohnEd]

Tom,

I don't have that slide protector to prevent selecting "gen" and "shore" at the same time.  I have inadvertently done that maybe 6 times over the years, slow learner, and so far it has not trashed the generator but it does HUMMMM loudly.  That HUMMM is what has saved it's life.

Thanks for the idea.  Won't work on my box so I guess I need a new box.

John

John

[Sean]

I don't have that slide protector to prevent selecting "gen" and "shore" at the same time.  I have inadvertently done that maybe 6 times over the years, slow learner, and so far it has not trashed the generator but it does HUMMMM loudly.  That HUMMM is what has saved it's life.

John,

You can kill someone with that setup, far away from your coach.

This is one of those cases where the code exists because the far-reaching consequences of mistakes may not be readily apparent.

I suggest you correct this problem with all possible haste.  The life you save may be your own, or a loved one's.

-Sean
http://ourodyssey.blogspot.com

[Sean]

Folks, my automatic switch burned up and the circuit board is more expensive than to purchase a new switch. ...

Grant,

If you give me the make and model of your switch, and maybe send me a couple photos of the damage, I can probably talk you through repairing it with a minimum investment in parts.

Failing that, simple three-pole 50-amp transfer switches can often be found at surplus for less than $50.

Post here or drop me a note.

-Sean
http://ourodyssey.blogspot.com

[BG6]

We have a separate receptacle for shore and generator.  To switch over, we just move the plug from the panel from one to the other.  You can't get more manual then that. 

Or safer.

No failure can cause genset and shore power to fight each other.

The whole automatic-switch thing is really kind of silly.  You park, get out, go around, pull the power cord over to the pedestal, plug it in, but somehow flipping a switch or swapping a plug is TOO MUCH WORK . . ?

[Dallas]

I have to agree there! lol.

I'd also like to add one more bit of information it took me a long time to figure out....

If you aren't running an auto transfer switch to change from Genny to pole power, make sure you shut off the main breaker to your breaker box before you unplug or plug in. The act of installing or removing the plug while power is still going to things like the fridge, microwave, TV, converter, etc., will cause the contacts on the plug and the receptacle to burn and fail prematurely. The cost of a plug is minor... but the hassle of replacing the darn thing in the rain when it's dark is a good way to learn a whole new vocabulary.

We have a separate receptacle for shore and generator.  To switch over, we just move the plug from the panel from one to the other.  You can't get more manual then that. 

Or safer.

No failure can cause genset and shore power to fight each other.

The whole automatic-switch thing is really kind of silly.  You park, get out, go around, pull the power cord over to the pedestal, plug it in, but somehow flipping a switch or swapping a plug is TOO MUCH WORK . . ?

[Sean]

The whole automatic-switch thing is really kind of silly.  You park, get out, go around, pull the power cord over to the pedestal, plug it in, but somehow flipping a switch or swapping a plug is TOO MUCH WORK . . ?

That's an unfair characterization, because there are plenty of other reasons to have an ATS, having nothing whatsoever to do with "work."

We're full-timers, and, occasionally, we have to leave the bus.  Sometimes, that's just for a day, in which case our pets are inside.  Sometimes, it's for a week or more, in which case, at minimum, we still have, for example, food in the freezer.  When we leave the bus laid up in this way, we maker every effort to have a power hookup -- sometimes as small as 15 amps.

With a manual switch or a plug-and-cord setup, we would be at the mercy of commercial power staying available, or the breaker on the pedestal remaining on and not off or tripped, or even the cord end remaining plugged in to the receptacle.  And I don't trust anyone else's breakers and receptacles beyond what I can test for myself -- more than once, we've had our campground power go out in the middle of the night due to park wiring, faulty breakers, etc.  Nor do I trust folks not to unplug us, or accidentally knock the plug out, or whatever.

With an ATS, I never have to worry.  If, for whatever reason, the shore power fails, the monitoring system will start the generator as needed to keep the batteries up, or the air conditioning running (for the pets, as needed).  The ATS means that the coach will switch over to generator power until the underlying fault is corrected.

In our case, with a load-sharing inverter, there is an additional reason:  We can often run the coach indefinitely on 10-15 amps of power.  However, at that low input level, certain conditions, such as the air conditioning coming on more frequently than we anticipated, will cause the batteries to continue to deplete, even though shore power is present.  Our inverter is set up to interrupt shore power when the batteries get below a certain point, via a relay in the ATS, thus causing the generator to start and the ATS to switch to generator power.  When the low battery condition has been corrected, normal shore power is restored.

Lastly, since we use the inverter for automatic generator starting, with a manual switch or plug-and-receptacle method, if we forgot to tell the inverter that the generator was disconnected, it might try endlessly to start it.  Hard on the starter, if nothing else, but, moreover, the generator would start over and over again, only to be shut down two minutes later by the sequencer, over and over again.

All that said, frankly, I do enjoy the convenience of just being able to push a button and have the generator connect automatically, and not have to go out and switch a cord, around, possibly in the middle of the night in crappy conditions.

YMMV, of course.

-Sean
http://ourodyssey.blogspot.com

[oldmansax]

B6G,

I have a "manual-automatic" because things in shore power change at in-opportune moments.

About a month ago we were staying in a campground when it snowed. we were all ready in PJs and the wind was blowing a gale. The  shore power started flickering on & off, causing a lot of fast switching on the inverter, not to mention we were using electric heat as the electric was included in the campground price. I was able to disconnect from shore power completely from inside & run self-contained until the next day when they got the electricity straight.

My transfer switch consists of two, 3 pole, 100 amp contactors with 120V coils and one double pole, double throw toggle switch, mounted in the bus. Shore power is connected to contactor #1 (T1=hot, T2=neutral, T3=hot) and genny is connected to contactor #2 same way. The load side of both contactors are tied together and connected to the inbound 120v elec feeds (L1+L1 to feed1 in panel, L2+L2 to neutral in panel, & L3+L3 to feed 2 in panel) for the bus, in my case, a 100 amp Square D panel.

I used some 4 conductor 14 gauge (I know, overkill) cable to feed into the bus for the control wiring. One side of the coil on contactor #1 goes to the T2(neutral) terminal. The other side of the coil goes to the upper terminal on pole #1 of the toggle switch. Use either hot side of contactor #1 (T1 OR T3) to feed the center terminal of pole one on the toggle switch. Wire  coil of contactor #2 the same way except using the LOWER and CENTER terminals of pole 2 on the toggle switch.

MAKE SURE TO FUSE EVERYTHING APPROPRIATELY! Sean will rap your knuckles or we will send flowers if you don't! 

The nice thing about this setup is you cannot bring on both the genny and shore power at once. If the switch is up, you get shore, if the switch is down you get genny. In the middle, everything is off.

The other nice thing is if there is no power to the shore cable, the contactor won't energize. Likewise for the genny. I have not done it yet but I am thinking about putting a 20 second time delay in the control wiring so if the power drops out, it takes 20 seconds of continuous power before the contactor will energize.


Dallas has been trying to get me to sketch this out but I have not had the patience to learn a CAD program. Anyone who knows one and wants to draw it, feel free.


TOM

[Lin]

I recently spoke to someone who said he has the generator, shore and inverter on one automatic transfer switch.  He said that it defaults to shore power if available.  If not, it looks to the generator and lastly taps the inverter.  How safe is such a setup?  Can it screw up and light two power sources at once?

[Sean]

I recently spoke to someone who said he has the generator, shore and inverter on one automatic transfer switch.  He said that it defaults to shore power if available.  If not, it looks to the generator and lastly taps the inverter.  How safe is such a setup?  Can it screw up and light two power sources at once?

Three-input ATS's are rare as hen's teeth, and I would guess pricey to boot.

They are safe, so long as their control systems perform as designed and are not modified.

I favor contactors that are mechanically interlocked (as well as electrically), and this is uncommon with a three-input setup.  However, it can be done.

Usually, BTW, transfer switches are set for generator priority, not shore priority.  If the generator is running, you want to be connected to it.

-Sean
http://ourodyssey.blogspot.com

[belfert]

I got my 50 amp Iota transfer switch on Ebay for under $100 a few years back.  It was surplus and works just fine.

[Len Silva]

I've had both and frankly, unless I was set up like Sean, I prefer the manual as long as it located inside the coach.  Don't want to venture out in a thunderstorm when the camp power goes out.

As far as the transfer switches are concerned, there are two different types.  The Iota and others rely on a pair of double pole, double throw relays and a timer/control circuit.  They work OK but I wonder about the possibility of one relay failing, thus transferring the power and not the neutral or vice-versa.

The other type (Todd Engineering, Lyght, and others) use mechanically interlocked 3 pole contactors.  I don't know about the comparative reliability, but I think the latter are more failsafe. They are actually three phase motor reversing contactors and very robust.