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Old 07-13-2005, 09:36 AM   #1
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1984 28' Funeral Coach
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Transfer Switch

I'm getting ready to install the Carrier Air V roof unit and then the Generac 40 Quitepac generator. As the old setup in the Champion was a manual twistlock pigtail that I had to change from generator to shore power I've not seen any transfer switch setups. I don't need automatic but would like to be able to switch over from my interior panel under the sofa. What am I looking for?
Also the coach had a generator switch on the panel that had the lettering covered over and it's never had a generator installed. Wonder if I can use it rather than the ugly Generac remote switch? Any ideas?
The coach is going to the dealer to begin it's repair and installation work the end of the week... your input is valuable to me, thanks
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Old 07-13-2005, 09:42 AM   #2
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Not sure about your first question- but the generator switch on the control panel should be able to be wired to remotely start your gen. The panel pulls out and you can look at the wiring ti see if it is already got any wires attached to that switch or if it needs new. Either way if the switch is there it should work. It is sure convenient. Also there is an a/c monitor light on that panel, that should come on when shore power or generator are working.
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Old 07-13-2005, 09:49 AM   #3
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I have a transfer switch that i got at Home Depot. The thing to watch out for is the circuit breaker rating. The 'off the shelf' units are limited to 15 amps, I don't know if that will handle your A/C.

http://www.airforums.com/forum...ead.php?t=9504
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Old 07-13-2005, 10:21 AM   #4
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Quote:
Originally Posted by GlenCoombe
... I don't need automatic but would like to be able to switch over from my interior panel under the sofa. What am I looking for?
Glen:

The 345's came with 2 automatic switches (definite purpose contactors).

One, mounted under the bed in the rear, switched automaticaly from shore power to generator. The other, mounted on the back of the generator enclosure (under the couch) automaticlay removed the "Rear AC" from the main selector switch - just like Lisa in "Green Acres", you can only use ONE "15" at a time - a manual switch above the cooktop in the 345 lets you select ONE and ONLY one "big amperage draw" (Front AC, Rear AC, Microwave, etc.) at a time.
With the generator running, the "second circuit" of the generator is dedicated(isolated) to the rear AC, allowing use of both the front and rear AC's together - only if the Generator is running.

The easiest thing, of course, for your 4 KW unit, would simply be to pick up a "relay" at an appliance/electrical contractor warehouse (commerical buildings use high amp contactor/switches in many applications), and automatically switch from shore power to generator power.

The "Champion Style" pigtail-manual-switch-it-over is certainly cheap and fool proof.
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Old 08-02-2005, 07:28 PM   #5
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Both airs?

87 MH, does that mean we can run both A/C units with only the generator running, or if the gen is running PLUS shore power?
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Old 08-03-2005, 07:12 AM   #6
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Only on the GenSet

Quote:
Originally Posted by pbnjsellers
87 MH, does that mean we can run both A/C units with only the generator running, or if the gen is running PLUS shore power?
The electric feed cannot be "mixed" without circuit modification. I'll try to explain.

The 6500 watt Onan in the 345 has TWO legs (separate circuits)...

- one leg goes to the main cabin isolator (contactor) along with the shore electric hookup. This contactor switch feeds electricity to the main electric panel. How this works is after the shore power electric line enters the MoHo it does not go directly to the main panel...it (the shore power line) first goes through the "main definite contactor". This is a switch that has both the generator main leg AND the shore power electricity coming into it. This switch will allow either the Shore Power ONLY or the Generator Power ONLY to go to the main panel...this prevents both the shore electric from feeding into the generator coils and the generator current from feeding into the shore power line (or powering up the exposed shore power plug while it is in storage). This contactor (GenSet/Shore Power Switch) works by sensing power (voltage) from the GenSet. When the GenSet is not operating the switch does not sense voltage from the generator, and the contacts are "at rest", and closed (switched) to the shore power - allowing the shore power line to feed into the main electric panel...this is the "normal" operation. When the contactor switch senses voltage from the generator for about two minutes (this is a "smart" switch - it delays the "switch" to make sure the generator has enough time to warm up) it (the contactor) switches the electric source to the main panel FROM the Shore Power feed TO the GenSet Power feed. So, this contactor makes sure the main panel is fed from one of two sources (the shore feed or the generator), and also makes sure the voltage/current from the two sources are never combined together. This contactor switch is located under the bed of the 345.

- the other leg from the generator (the second leg) goes to a similar definite purpose contactor (this one located on the cabin side of the generator enclosure on the 345). This contactor works in a similar fashion to the main power feed, except it feeds only the rear AC - the contactor breaks the circuit from the main panel/main selector feed and allows current ONLY from the genset secondary circuit to go ONLY to the rear AC.

Hope this helps - PM me if you require more detail on the operation.
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Old 10-18-2008, 09:58 PM   #7
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1986 34.5' Airstream 345
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345 Relays

87 MH.
Do you or could you supply a wiring diagram as tom how these two relays are wired? I think I messed up thinking that the shore feed wire from the j box by the reel fed directly to the panel above bed. I disconnected and ran a new wire to the panel and now when on generator power, I have no power to selector above range nor to panel above bed. I think I can correct but diagram would be very helpful. Thanks, Smokepole1
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Old 10-20-2008, 08:17 AM   #8
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Quote:
Originally Posted by smokepole1 View Post
87 MH.
Do you or could you supply a wiring diagram as tom how these two relays are wired? I think I messed up thinking that the shore feed wire from the j box by the reel fed directly to the panel above bed. I disconnected and ran a new wire to the panel and now when on generator power, I have no power to selector above range nor to panel above bed. I think I can correct but diagram would be very helpful. Thanks, Smokepole1
Here is a link describing how the 120vac wiring is laid out in our 1984 310 Motorhome. Other than the physical parts location its wired the same as in the 345 motorhomes.

http://www.airforums.com/forums/f311...ion-41259.html

Hope this helps.

Brad
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Old 11-09-2008, 08:54 PM   #9
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I had posted this drawing previously, which should answer some of the queries about transfer switches.

http://www.vsquare.com/howard/photos...lectric002.jpg

This circuit was used to modify the existing 30-amp shore power of my '94LY to what is referred to as 50-amp. It really is 2 legs of a 115-115 volt (230volt) power, just like what you have coming into your house.

What you have to know is that there are 60-second time-delay relays used in this circuit (which is the rewiring of the 2 ATS switches in my '94LY) which are critical to prevent damage to you rig. When your generator starts, it is not immediately ready to deliver full power, so the mechanism that ensures that you don't attempt to inadvertently start your microwave or other 120-volt appliance before full power is actually available. FYI, I did, at one time, source these time-delay relays - they are not all that costly - just $10 each.

The shore power cord needs to be 4-wire, but you do not have to up the thickness or gauge, as the amperage stays the same (30 amps on one leg), just the voltage is increased.

If you look around at some of the surplus electric suppliers, you may be able to luck out (as I did) and get a 100-foot length of the stuff - I no longer have to carry extra heavy extension cords.

We did this modification about 2 or 3 years ago, and it has worked flawlessly.

I would STRONGLY recommend that you have an trained and certified electrician do the work, as there may be insurance issues if there is an error made. The person who designed this modification, who designs and builds industrial equipment used in the food industry, also contacted CSA to get verbal assurances that what he designed was valid and not in contravention of any standards. I cannot stress the importance of this, as you may otherwise invalidate your insurance.

Howard
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