NamMedevac 70
Reno
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Great discussion
* This post was
edited 06/15/23 02:46pm by NamMedevac 70 *
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ScottG
Bothell Wa.
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Joined: 02/25/2005
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A simple rule to follow with 30A is to only have two heavy loads on at once. So Water heater, micro, AC, space heater, etc. Any two of those is OK but if you're going to run say the micro and AC, it's best to turn off something that might come on unexpectedly, like the WH.
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ktmrfs
Portland, Oregon
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Samsonsworld wrote:Dang, I think the microwave in my current unit is 700w. And I think my last two were 900w.
Might take 444 seconds for that meal.
and that is OUTPUT power, NOT input draw. a 900W microwave will draw around 1300VA they have terrible power factor and lots of power loss.
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ktmrfs
Portland, Oregon
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pianotuna wrote:Samsonsworld wrote:
Not everything turns on or surges at the same time. Its just not as big a deal as some make it out to be.
Mitch, 12a shocks me on the water heater. (edit: Yep, 1400w/120 = 11.6...most inefficient thing on there.)
"inefficient" resistance heat uses 99.9% of the energy.
Where one needs to worry is motor operated devices such as the horribly inefficient roof air conditioners. Below 107 volts there is ongoing cumulative permanent damage to the device.
If I'm in that situation I connect the autoformer. I've used it at an input voltage of 97 on a 15 amp circuit successfully. I did have to move the fridge to propane there were no other 120 volt loads except for the inverter charger. The house batteries were fully charged.
I do limit energy input to 24 amps using the inverter/charger and often have the load support feature active.
The largest load is the microwave at 1570 watts. I don't "cook" in it but do thaw home made meals. 222 seconds and my knife and fork are active.
RV roof ac units as you mention are not very efficient, but since they are just moving heat, even the worst one will move around 3-44BTU for every BTU of input power. The typical roof AC unit is around 13.5KBTU and the input draw is about 12A, or 1450W= 4300BTU input, 13.5KBTU out. Around the same for a heat pump ac unit, for 4000BTU in you will get around 13K BTU out. 3x that of resistance heating.
A sticks and bricks AC unit trounces that.
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Samsonsworld
West Texas
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ktmrfs wrote:Samsonsworld wrote:Dang, I think the microwave in my current unit is 700w. And I think my last two were 900w.
Might take 444 seconds for that meal.
and that is OUTPUT power, NOT input draw. a 900W microwave will draw around 1300VA they have terrible power factor and lots of power loss.[/quot
e]
Yeah, I don't know about that. A 1500 watt is about all a 16a breaker can handle. You're telling me its really over 2100w?
I tend to agree on the efficiency of an ac. That 12a (probably more like 14a) on the ac is start up surge. Probably runs at 7-8a. And cycles off to like 2a on the fan. Could be worse.
* This post was
edited 06/15/23 04:39pm by Samsonsworld *
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Boomerweps
Hills of PA
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For 30 amp service, use the rule of three, as in 3 is too much. AirCon, water heater, microwave. Use only two at a time. Often the three might play well together, but when you throw on another heating element of any kind (toaster, coffee maker, electric skillet) or the DC converter, it’ll often trip a breaker.
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cummins2014
Utah
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Samsonsworld wrote:Lantley wrote:Samsonsworld wrote:All I can say is they were all turned to electricity. Whether they were all running, I never paid much attention to. But I don't go turn one off before turning another on, and I can't recall any issues. Believe what you want.
While I can't dispute your experience. It is not the norm. Typically you cannot just let those items run together without tripping a breaker on a 30 amp circuit.
Been going to the same state park for 25 years. The spots I like are 30amp. 5 different trailers, though only the last 3 had an electric water heater. Sounds normal enough to me.
Now throw in a hair dryer.....different outcome.
Having read this thread , we too stay at that same park here in Montana every summer for the past 22 years . Although it never gets hot enough to run both air conditioners , we run one on occasion with the 30 amps . We never experience a tripped breaker only if like some say , air conditioner can be running , and water heater on electric we are okay ,but anything else like a microwave , hair blower etc will trip it . It's been pretty simple either shut off the switch for the water heater or air conditioner , and then we can do about anything we need . Not a big deal for us .
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cummins2014
Utah
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Boomerweps wrote:For 30 amp service, use the rule of three, as in 3 is too much. AirCon, water heater, microwave. Use only two at a time. Often the three might play well together, but when you throw on another heating element of any kind (toaster, coffee maker, electric skillet) or the DC converter, it’ll often trip a breaker.
Thats a great rule of thumb . Anyone doing otherwise , usually will not get away with it . As said 22 years same park ,same 30 amp service with four different RV's ,and its always been the same . run two ,can't run three usually .
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dodge guy
Bartlett IL
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When we had the TT I would run the AC, water heater and micro wave. Never had an issue that I’m aware of. Although not knowing is always better than knowing LOL. Never had any kind of EMS until now. Now that I have it I watch it.
If you switch the water heater to LP only then you should be fine. And if it’s hot out the compressor will only startup once eliminating the startup draw of the compressor.
* This post was
edited 06/21/23 01:49pm by dodge guy *
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Cptnvideo
Arizona - most of the time
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Slightly off topic, but I wanted to share.
We are boondocking at 5350' elevation in central AZ, high yesterday was 86°. We ran one A/C unit (soft start) for 6 hours. Batteries were down 597 ah this morning. (See signature for solar setup.) Fans and open windows today to allow batteries to recover. We might run A/C for a couple hours later today as we will be plugged in at Prescott tomorrow (rodeo in a few days).
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