Surge Protector - Progressive, or something better?

pianotuna wrote:
According to Dometic, amp rating on a 13500 btu unit is 13.4 amps. Locked rotor amps are 63. They don't list the name plate voltage. The do want #12 wire for runs under 24 feet. More than that and they suggest checking the national electric code.

Dometic air conditioner

If we assume 115 volts then wattage is 1541. I know I've seen as low slightly under 1200 and as high as 1900. At 1900 and 106 volts that's over 17 amps flowing through the motor. I can't imagine this is good for it, as a 10% tolerance would be about 14.75 amps.

I don't doubt your figures, Don, but I think the AC motor may be more rugged than you suggest . . .

I just base that on the over 10-year-old residential fridge in my park model. The campground voltage can sag to 102V each summer, and there has been NO autoformer hooked up to that park model.

The fridge is still working just fine.

I don't suggest that low voltages are a good thing (since I use an autoformer), but I think many of the motors RVers use are pretty forgiving.

According to Dometic, amp rating on a 13500 btu unit is 13.4 amps. Locked rotor amps are 63. They don't list the name plate voltage. The do want #12 wire for runs under 24 feet. More than that and they suggest checking the national electric code.

Dometic air conditioner

If we assume 115 volts then wattage is 1541. I know I've seen as low slightly under 1200 and as high as 1900. At 1900 and 106 volts that's over 17 amps flowing through the motor. I can't imagine this is good for it, as a 10% tolerance would be about 14.75 amps.

TechWriter wrote:

CA Traveler wrote:
And I've emailed about specs and price.

I suspect that these are very expensive units and they are certainly rather large in size.

Did they ever get back to you? They haven't answered my request for specs yet.

Not yet.

115V is the Dometic spec in the manual and hence there is no information on high/low limits. We don't often see voltages below 108V but good to know that the PI will shut down at 104V.

Last summer when it was hot I had my first low voltage on 50A. The park was full with lots of ACs running and it was an older park so age might be a factor.

Hi,

Tolerance is often (but not always) 10% so 115 name plate suggests that 103.5 is the lower limit. With 120 volt that becomes 108 volts.

I'll stick with 108 myself for the lower limit.

I do know that last year at a campground on a hot sunny day I had to turn off everything except for the air conditioner. This summer if it is hot, I'll spend the money for a 50 amp site (if available).

The air conditioner was drawing over 1900 watts. That is a sure indication that voltage was too low for my comfort zone.

The thirty amp pedestal breaker blew twice with just the air conditioner running. I suspect old tired breakers and minimal wire size in the RV park.

There is an autoformer in my future.

CA Traveler wrote:
OK But what is the lowest voltage for the motor? My Dometic says 115V period. So do I turn it off at 114V or at 107V or whatever?

And your motor may be different and it may not be 108-132?

Just raising what-ifs?

Gjac wrote:
I primarily dry camp so I don't worry about this much, but if I used electrical sites I would not feel comfortable with a Surge guard allowing the AC's to run at 104 volts for hrs on end. I posted a while back about these Klixon switches that can shut the power of at selected voltages, many on the forum were not familiar with these. I am not an electrical person but I would think some kind of switch that cost $10 and would shut the power off at 108v would be safer than some type of $400 surge protection that does not cut off until 103v. Am I missing something?

You should actually read the specification of your AC unit. That will tell you the range, in volts, that your AC will safely run without damage. It's purely a motor concern so that the windings do not heat up and cause damage.

-paul

CA Traveler wrote:
And I've emailed about specs and price.

I suspect that these are very expensive units and they are certainly rather large in size.

Did they ever get back to you? They haven't answered my request for specs yet.

I run an autoformer down stream of the surge guard. So, if the voltage sags but is still higher than 103, the surge guard will let it go through but the autoformer will boost it before letting it go into the rig. But, if the voltage sags below 103, the surge guard will cut power off completely, which is OK with me, since that's too low to deal with anyway.

I primarily dry camp so I don't worry about this much, but if I used electrical sites I would not feel comfortable with a Surge guard allowing the AC's to run at 104 volts for hrs on end. I posted a while back about these Klixon switches that can shut the power of at selected voltages, many on the forum were not familiar with these. I am not an electrical person but I would think some kind of switch that cost $10 and would shut the power off at 108v would be safer than some type of $400 surge protection that does not cut off until 103v. Am I missing something?

115V is nameplate rating.