A/C Breaker needed?

[Fjatheart]

Newb question here. I’ve already prepared myself for the lashing, so fire away 😬

Considering installing a roof A/C and using a generator or shore power to run it. If the generator and the shore power have the appropriate 20amp breaker, do I still need to or should I still install a 20amp breaker between the A/C and power source? Seems like 2 breakers doesn’t make sense. What am I missing?

I would like to run 12 ga Romex from the A/C unit to a 20 amp shore/RV plug on the exterior of the bus where I can plug in my generator or shore power. The rest of my power needs run off a separate 12v system.

Thank you

[Ninjakitty]

I installed 20 amp breaker between the rooftop a/c and the 20 amp exterior inlet. I don't want to have to rely on some random breaker/power pedestal that I dont know to protect my equipment.

[BlackJohn]

If you can at all run #10 from the ac to wherever your power is. It is ideal for your setup.


Breakers? All breakers are not equal. A 20 amp isn't a 20 amp breaker?

In every aspect but the trip time designed into them. Some will hold longer than others, be it seconds of time or milliseconds. Two is not too many and does protect life and limb as well as the equipment it is connected to.


Your budget determines if you need/want that extra protection.


John

[Fjatheart]

Can someone direct me to a tutorial on wiring a alternating current breaker into a vehicle? I’ve only wired 12volt set-ups. I understand I’ll have to buy a breaker box, breaker, Romex, etc, but I have no idea how to set-up a neutral and a ground. I assume the ground would go to the frame or bus bar, then to frame, similar to a DC set-up, no?? The most direct instructions would be greatly appreciated.

Thank you

[Ninjakitty]

Originally Posted by BlackJohn

If you can at all run #10 from the ac to wherever your power is. It is ideal for your setup.


Breakers? All breakers are not equal. A 20 amp isn't a 20 amp breaker?

In every aspect but the trip time designed into them. Some will hold longer than others, be it seconds of time or milliseconds. Two is not too many and does protect life and limb as well as the equipment it is connected to.


Your budget determines if you need/want that extra protection.


John

This is what I ran

[Ninjakitty]

Originally Posted by Fjatheart

Can someone direct me to a tutorial on wiring a alternating current breaker into a vehicle? I’ve only wired 12volt set-ups. I understand I’ll have to buy a breaker box, breaker, Romex, etc, but I have no idea how to set-up a neutral and a ground. I assume the ground would go to the frame or bus bar, then to frame, similar to a DC set-up, no?? The most direct instructions would be greatly appreciated.

Thank you

With 110/120 volt alternating current, you don't ground it to the vehicle. If your coming from shore power, it grounds to the pedestal. If your coming from a battery bank and inverter, the inverter should have its own separate ground that isn't run on the AC input/output of the inverter. There are more experienced/knowledgeable people here than me, but this is what I've learned from them and my research.

[Ninjakitty]

As far as simple derailed instruction, if running 30 amp power (I don't know how to set up for 50 amp, but it is similar):

1: 30 amp power inlet. Connect hot(black), neutral (white), ground (green) to the correct holes in the back of the inlet.

2. Using the appropriate gauge wire (10 ga or thicker) connect the other end of the wire into the correct areas in your main work center/breaker box. Plenty of YouTube videos on that.

3. From your individual breakers run the appropriate gauge of wire to your outlet/appliance, connection the hot, neutral, ground to the correct tabs/connections on the switch/outlet/light/etc...

That is the real basic part of it. You will need to know load size for each run to for wire sizing, breaker size needed for the run, correct outlet amperage. For example, you don't want to use a 15 amp outlet on a run that has a 20 amp circuit breaker. The outlet will fry before the breaker can trip.

Anyone feel free to chime in and correct me if I am wrong on any of this. I am not an electrician and I am not certified to give professional advice.

[roach711]

Originally Posted by Ninjakitty

With 110/120 volt alternating current, you don't ground it to the vehicle. If your coming from shore power, it grounds to the pedestal. If your coming from a battery bank and inverter, the inverter should have its own separate ground that isn't run on the AC input/output of the inverter. There are more experienced/knowledgeable people here than me, but this is what I've learned from them and my research.

Definitely ground your AC breaker box to the bus body to avoid the "hot body" condition which can give you a nasty shock. Without that ground connection a loose hot wire touching the steel body won't trip the breaker and you'll never know you have a problem until someone touches the body and gets shocked.



The ground wire in an AC circuit doesn't normally carry any current like a DC ground wire does. It's there as a safety feature rather than a part of the circuit.



Your bus AC panel should be a "branch box" with separate ground and neutral bus bars. The ground/neutral connection should only happen at the main shore power breaker box.

[Ninjakitty]

Like I said, I'm no expert and there are people here with more knowledge than myself. My inverter has a an auto transfer switch and is grounded to the frame and my short power goes to the inverter first. It will be different for different setups and equipment

[PNW_Steve]

The ground bus in your breaker box should be grounded to the chassis. THE NEUTRAL BUS SHOULD NOT. Some panels come new with a bonding strap that needs to be removed.

Ground and neutral should be bonded at the shore power connection not in the panel on the bus.

If you run a generator it should bond ground and neutral. If it doesn't then you need a bonding plug similar to this :https://www.microair.net/products/ge...12272654155860

[Ninjakitty]

So tell me if I am understanding this correctly, in the 120 volt AC, the ground wires in the breaker box should have a grounding run to frame or chassis. This is in case a hot 120 line breaks/comes loose and hits the metal. This ground wire will keep the bus from getting "hot skin."

[PNW_Steve]

Originally Posted by Ninjakitty

So tell me if I am understanding this correctly, in the 120 volt AC, the ground wires in the breaker box should have a grounding run to frame or chassis. This is in case a hot 120 line breaks/comes loose and hits the metal. This ground wire will keep the bus from getting "hot skin."

That is correct.

Be mindful of correct neutral/ground bonding as well.

[Ninjakitty]

Thanks. I'll add some grounding runs to my breakers boxes