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Old 08-13-2019, 09:43 AM   #11
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Originally Posted by Dboland9 View Post
Again, thanks to all for your thoughts. It is an RV 30amp, 30 ft, 10G cord with RV plugs. I do agree that if the electrician was thinking he put in a larger gauge from the house to the pedestal to minimize voltage drop off. I will be speaking to him to see if he has those records.

I am still insecure with running it as the voltage did drop to 109 and Dometic said that was the lowest voltage they were comfortable with.

I like the suggestion about the soft start and will embark on some research. Thanks
I really wouldn't get too worried about running it down to 104 volts. There's tens of thousands of RVs out there every day running them at those low voltages. If you look at the AC you'll most likely see that every sticker you can find says it's rated at 115 volts.

If it was a real problem Progressive and all of the other EMS manufacturers wouldn't have a low voltage cutout at 104 volts.

On hot and muggy days when the system is stressed our household voltage typically runs 112-114 volts. And I'm sure there's millions of homes out there that run at lower voltages all the time during heavy loads.

I only worry about it if starts to get down around 105-106 as it's getting close to the 104 limit of my EMS and I don't want to start having the EMS shutting power off and on to the trailer.

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Old 08-18-2019, 07:28 AM   #12
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Here's a tip... Never leave an extension cord coiled up. Completely unwind it. Heat can build up when drawing near the max Amperage of the cord and can melt the cord. It recent happened to a fellow RVer.

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Old 08-18-2019, 08:06 AM   #13
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You might want to try one of these line regulators that protects against under or over ac voltage, in effect a voltage stabilizer:
Technology Research 10176 30 Amp Voltage Regulator

I bought the 50A version for my Class A a few years back

We were staying at the only RV park up in the 1000 Islands which was anywhere near the marina where we were keeping our boat. We were there for the summer and the RV Park had serious Voltage issues. I was regularly seeing voltage on one of the 50A legs dropping to 109 and below and was worried about my A/C units on that leg. Fortunately someone suggested one of these regulators and I never had another problem. Whenever voltage would drop at the pedestal, the LED lights come on indicating the regulator, which is actually also a stabilizer, would kick in and my voltage would jump right back up to 118. Worth its weight in gold.
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Old 08-18-2019, 01:58 PM   #14
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Question: Where are you installing your EMS? If it is installed at the pedestal and then you are adding 55' of cords downstream, then you really don't know what the voltage is at the AC unit. Hopefully you have it installed downstream of your cords as close to the trailer as possible in order to get true voltage being applied to the trailer.

Most everyone will probably disagree, but if you are seeing the voltage drop to 109 at the trailer with only the AC load, that's nearly 9% drop over the "standard" of 120 and indicates to me your 30A service is significantly undersized. I wouldn't run an AC or refrigerator on this service.
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Old 08-18-2019, 02:04 PM   #15
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Originally Posted by LHaven View Post
You may want to attack this from a slightly different perspective, which is that 115v in the household sockets is marginal to begin with. Yeah, I'm old enough to remember when 110 was the standard, but it's been 120 for 50+ years now. If you can get your electric company to adjust your local transformer, you may finesse out of your RV problem.
Most utility transformers do not come with tap changers that adjust output voltage. The utilities do have the ability to adjust the primary voltage going to the transformer, but that will only happen if the primary (high voltage) circuit is lower than what it is supposed to be. We were required to maintain voltage within 5% above or below 120 volts at the main panel, which would be 127 - 113 volts, and beyond the customer panel, it is the customer's problem, which is to install large enough wire to reduce any voltage drop.
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Old 08-19-2019, 03:02 AM   #16
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Everyone is giving you great advice. Thought I would comment from an old maintenance electrician stand point. Current increases as voltage drops so...
If voltage drops the 1st thing which may happen is the circuit breaker could trip. If you trip the breaker it could just be too much voltage drop. Everyone is giving you good advice.
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Old 08-19-2019, 07:58 AM   #17
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Amperage is the "working load that produces heat" part of electrical items.

As voltage (the pressure in the hose) goes down, the current (volume in the hose) must go up to maintain the amount of "work" the appliance performs.

As an example:
1600 watts at 120 volts carries 13.3 amps through a circuit breaker
1600 watts at 104 volts carries 15.4 amps through that same breaker...

So, in this example, if you're plugged into a campground pedestal supplying 30 amps to your trailer and the voltage is 120 VAC, your air conditioner drawing 1600 watts will run "OK" with a 15 amp breaker but will "trip" the breaker if the voltage drops to 104 VAC.....

On the "other side of that equation", most air conditioners are wired to 20 amp breakers. So, it's going to be a "happy camper" buzzing along at 120 VAC while drawing 1600 watts. With that 20 amp breaker, if the voltage drops to, say 95 VAC because of heavy useage on the campground grid, that 20 amp breaker will not protect your air conditioner (designed for 13.3 amps of current) from receiving the increased current required to maintain 1600 watts to the compressor, which will be in the 16.8-17 amp range... That will produce increased heat in the compressor, probably damaging the internal components... It may "keep on running while almost smoking" that weekend. But sooner or later, the results of being overheated will take its toll and you'll be replacing the rooftop unit.

The 20 amp breaker won't "protect your air conditioner" from low voltage or high current.... That's why an EMS is so vitally important.


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