additional roof top wiring

[busshawg]

Here I am once agin looking for advice. I only have one roof top at persent. My gen set has a 30 amp breaker and a 20 amp breaker and is a Honda 6010. The bus is wired to the 20 amp and my exsisting roof top is wired to the 30 amp., with a 30 amp receptacle between the gen set and A/C unit. Now my question is where and how do I wire up my second A/C unit to. Does that 30 amp service from my gen set support 2 units? Can I add a second receptacle to this breaker? Sorry for my ignorance.

Grant

[FloridaCliff]

Grant,

I would have one a/c on the 20A circuit and the other on the 30A plus your other bus power needs.

The opposite of what you said your situation is now.

I don't know what rooftop a/c units you have, but figure up to 15A starting load would be generally safe.

Since you shouldn't go over 80% load on a circuit, you will be fine on the 20A and  the additional a/c shouldn't be a problem at all on the 30A, plus you have almost 15A still available on that circuit, again, this is a rough estimate without your exact usage.

There are a lot of unknowns here on your specific situation and what other power demands you have.

Like, do you have electric water heater, size of refrigeration...etc...With these added you may have to do some load management on the 30A leg.

Cliff

[busshawg]

Thanks Cliff. My bus is set up for mainly boon docking, propane fridge, propane water heater, 12V lights, water pump. So the only things that would run off of the gen set would be the TV, DVD, microwave and addition small kitchen untensiles and battery charger. I have a carrier 13,500 A/C unit now and hope to add the same if I can get this one working properly. Can I simply plug a addition unit into a exsisting 120 recpectacle that I have hardwired into the bedroom now? It has 14/2 wire going to it. Or do I need to run a 10 gauge wire up to it from my breaker box. Thanks

Grant

[Jerry32]

#14 ok  to 15 amps Jerry

[FloridaCliff]

Grant,

I would run a separate circuit of 12/2 on a 20A breaker.

I have the 13,500 units like you and they can pull 12-14 amps on a cool day on start-up.  Now if the voltage has dropped or its hotter, it could go even higher.

Just remember to never exceed 80% of a breakers rating to be safe.  14/2 = 15A X .80 = 12A
12/2 = 20A X .80 = 16A

As a side note, I ran 10/2 to mine to virtually eliminate any voltage drop in the wire, protected by a 30A breaker.  This also allows me to move up to 15,000 btu units in the future without any hassle.... Just my way...

Cliff

[Sean]

Actually, the manual for your A/C should specify what type of circuit it needs.

Most 13.5 kBTU/h units require a 20-amp circuit.  My units run 13 amps steady-state, and that can easily double while starting.

For your generator setup, I would, as has been suggested, run one unit on the 20-amp circuit, and then run the 30-amp circuit to your main panel, and run the second A/C off that.

-Sean
http://ourodyssey.blogspot.com

[busshawg]

So from what you are telling me the unit I have at present may not be operating properly because I have a 14g wire running from a reugular house hold outlet that is hooked up to my 30 amp breaker off of the gen set. I bought supplies, 10 gauge wire and 30 amp outlet and male plug end for this connection, just to try to trouble shoot. Or do you believe the unit should operate as is. It cycles prematurely. Blows cool for a little while, then the compressor cuts out and the fan continues to run. This is my last resort to try to get this thing working. When I place my hand on the bubble the compressor cuts back in. I'm thinking maybe a lack of power. The RV place doesn't want much to do with me as they are "busy". Plus they want 75 bucks just to book me in.

[Airbag]

I use 12 guage wire minimum for the roof AC's. My gen has one 30 amp breaker next to it and out of that box it feeds a breaker box downstairs and a breaker box upstairs. Use what ever breaker the AC manual says to use.

[Sean]

So from what you are telling me the unit I have at present may not be operating properly because I have a 14g wire running from a reugular house hold outlet that is hooked up to my 30 amp breaker off of the gen set. I bought supplies, 10 gauge wire and 30 amp outlet and male plug end for this connection, just to try to trouble shoot. Or do you believe the unit should operate as is. It cycles prematurely. Blows cool for a little while, then the compressor cuts out and the fan continues to run. ...

It is possible that your A/C problems have to do with the wiring.

You don't say how far from the transformer or main panel you are running with the #14 wire.  However, all circuits present what is known as "voltage drop" -- when you measure the voltage at the A/C's input terminals with the unit off, you might read 117 volts.  However, when the unit starts up and is running, you might measure at the same place and see only 102 or 103 volts.  That sort of low voltage will cause some of the symptoms you describe.

You should get a good quality DMM and measure the voltage at the input terminals with the unit off, then again when it's running, and this will give you an indication of whether this can be the problem.

-Sean
http://ourodyssey.blogspot.com

[busshawg]

Thanks again, I know the voltage was reading 124 at the outlet in the cargo bay and 120 when the A/C is running. I can't remember how many feet of wire I have running to the unit from this point, but I do know it is quite a few.
I will check the voltage tonight at the A/C unit itself, it seems like I keep running out of time to do everything. I think I will end up running my 10 gauge anyway just to be on the safe side. If I ever do get a service guy to look at it, I'm sure that will one of the first things he mentions anyway.

Grant

[busshawg]

Just an update, The problems with my new A/C were not anything I did upon installation. Although with my 14 gauge wire I was looseing 1.5 volts from the gen to the A/C so I ran 10 gauge wire, it's good now.

The problem was the thermostat, it was bumbed right from new. First of all I hooked up a household thermostat and it worked fine, so for the time being I simply have it connected  straight , without a thermostat at all, it works and blows nice a cold.

Thanks for all of yor help!