5th wheel living issues
We have a fifth wheel that we live in full-time (at least in the summers). We are running power to it from a shop my husband owns. I don't think the a.c. is big enough, it probably needs 2 a.c.s, but...
Forum Discussion
What is the power cord going to the shop? Is it a 4 blade 50 amp cord or a 3 blade 30 amp cord? Are there any adapters or extensions on the cord?
When the 30 amp breaker trips does the main AC continue running? If so you are probably on 50 amps.
Without having any more information I can only hazard a guess.
If the 30 amp breaker is working fine with the portable AC unit running right up until there is a second significant load on the system. A load such as the water heater (on electric) coming on. Or the Microwave turning probably trips the breaker. If this is the case then you just need to be careful of your loads. Turn off or put the water heater on propane when you're running the portable AC. Temporarily turn off the portable AC to run the microwave. You can turn it back on once the microwave finishes.
Lack of water pressure can be many things. Are you running your water off the onboard fresh water tank and pump? Or are you hooked up to water from the shop?
If it's lack of pressure and flow out of the faucets try unscrewing the aerators out of the end of the faucet. With the aerator off you'll know immediately if it was plugged up and causing the problem. If you're on shop water try putting water in the fresh tank and run off the pump. Is there a difference?
About the only way 2 AC's can be run from a 120Vac 30 amp connection is if they are both using (good) "soft starts". 120Vac 30 amps is only 3600 watts and a 15k btu roof AC will need over 2500 watts to start the compressor. That only leaves 1100 watts available, not enough to run a portable AC.
To make matters even more confusing, the 30 amp rating is the ampacity rating. This means that the actual amp rating is 24 amps or 2880 watts. The breaker will generally trip after several minutes at about 25 to 27 amps.
This is why larger RV's have 240Vac split phase 50 amp systems. These are capable of up to 12,000 watts based on 50 amps ampacity. The actual amp rating is 40 amps or 9,600 watts. This is enough to run 3 roof AC units with a small amount left over. If each AC unit draws 2000 watts while running, that is 6000 watts, leaving 3600 watts for other devices. With 3 roof AC units it is best to stagger start them so that the don't trip a breaker (or better yet use soft starts).
To make matters even more confusing, the 30 amp rating is the ampacity rating. This means that the actual amp rating is 24 amps or 2880 watts. The breaker will generally trip after several minutes at about 25 to 27 amps.
a 30 amp breaker is actually rated for 30amps continuously at 120V so 3600watts. the wire and fixtures are rated even higher but the breaker is your cut off point. for design purposes if you are going to run a load for 3 hours strait then you size it to 80% of the household circuit, that's what you might be referring to. the reason for this is eventually over time it will prematurely wear out the breaker. you see a lot of this in old houses with the 30amp breaker the stove/oven is on. newer ranges use pretty much that full capacity so if you do a lot of baking while cooking on the top eventually your breaker gets week and you start popping one leg. you can replace it with a brand new 30 amp breaker and be good for a couple years or so then replace it again, or you can pull a new 40 amp rated wire and install the 40 amp breaker and be good for the foreseeable future. if the breaker won't hold hours at a full 15 amps you have a defective or worn out breaker. but yes household design for circuits is to only load them to 80% of the capacity, but the reason is so there is room in the future to tap into runs with out having to pull new wire for the whole circuit.
AC's are not a continuous load as the compressor turns on and off as needed, only the fan is constant, so ya what could be happening is when they start up and the other one is running it is spiking over the 30 amps and tripping the breaker. then the more this happens the weaker the breaker gets and the lower and/or faster it will trip.
I have been having fun with my 1970's house and previous owners that did their own electrical with out having a clue. I think I have moved 12 circuits off the main panel onto a sub panel now and replaced 60% of the breakers. as well as replacing probably 300 feet of shoddy wiring that doesn't come close to meeting code but made it through all the inspections over the years 🤔
RV roof AC's are not very efficient and RV's are not insulated well, even "4 season" RV's. If the RV is somewhere where the ambient temp is 90+F and in direct sun it is likely that the AC compressors will run continuously for most of the day.
Ampacity is tricky. According to code it is 80% of the wire's full load capacity. Many people just look up the amp capacity and call it good, but that's not how it works. Normally the first part of the wire to fail is the insulation. The insulation will have a temperature rating and usually specify how and where it must be run. That temperature rating is based on 25C/77F ambient temperature. If the wire is in a location where the ambient temperature is higher, it's amp rating will be less than specified. Somewhere in the wire specification will be a temperature coefficient. The temperature coefficient will tell you how much to reduce the amperage per C of temperature increase above 25C.
As wires and cables tend to be in places without good airflow it is common for the ambient temperature in that location to be much higher than the ambient air temperature. This is especially true in RV's. Many RV's have most of the wire runs in the ceiling. If the air ambient temperature is 90F or 32C, those wires may be 120+F or 49C. The wire run to the air conditioner is ROMEX, which is rated for 90C/194F. An ambient temperature of 49C means that the ROMEX is derated by about 82%.
The ampacity rating has nothing to do with "so there is room in the future to tap into runs with out having to pull new wire for the whole circuit".
The ampacity rating is a safety buffer to help with wires that are not connected well, with ambient temperatures above 25C, with wires that are bent at too sharp of an angle producing localized hot spots. It's there to help prevent the wires from failing which will cause a fire. It also has nothing to do with residential, it's industry standard and national code. In the US, it's the National Electric Code or NEC.As for why the breakers trip "early", I believe that many cheaper breakers list their amp rating, not their ampacity rating. So often they trip at about 80% of the expected value. I've seen brand new 240Vac 50 amp breakers trip at about 40 amps. I haven't been to any campground that can handle the full rating for more than a couple of minutes. It doesn't matter if it's 240Vac 50 amp or 120Vac 30 amp.
I have a large solar system installed in my RV with (6) 48v 100ah batteries and I can charge them at a high rate. I've never been able to pull more than about 10,000 watts from a 240Vac 50 amp circuit, and about 3000 watts from a 120Vac 30 amp circuit. At home, I have a 240Vac 30 amp circuit breaker. It will trip at about 24 amps after about 15 minutes. If I was going to stay in the house longer, I'd replace it with a 240Vac 50 amp circuit breaker and replace the cabling to hander the higher amperage.
I can only run both my air conditioners on SOME 30A circuits.
I am thinking of getting a portable AC but I would run a heavy extension cord to an extra receptacle - not through the RV panel. Of course, her husband's shop might not have another circuit available.
My 5er is 42' and it needs THREE ACs.
I was going to say that very very very few 40 foot 5th wheels come with a single AC. Even two 15K btu AC units is tough with that large of a 5th wheel.
I have a 35.5 foot (floorplan) 5th wheel with a 15K btu and 13.5K btu AC and if I don't start them early (before the inside temp hits 70F) they will really struggle in 90F temps. I'm thinking about upgrading the 13.5K btu AC to a 15k btu.
a lot do, depends where you live. in the northwest and Canada almost all 40 and 42 foot 5th wheels have 1 ac and are prewired for a second. yes you can get them with two, but those are special ones from the factory or the dealership ordered it with two. a second or third ac is an addon and a "money maker" so usually they are not in the base. my 5th is 42 feet long (overall) and has 1 ac prewired for a second, no way to add a 3rd unless you fish new wires through the walls and celling. it was a 89K 5th wheel.
