complaints when using a hughes autoformer
I am looking at a used hughes autoformer. I know some parks rules say they are not allowed. Some parks we have been in, I have seen voltage at @ 102 to 104 with my a/c on. I would be using a PI 3o...
Forum Discussion
A simple/short answer (sorry!). :R
The way an autoformer works is simple: power in = power out, minus autoformer internal losses. If voltage is down on the input side and voltage is up on the output side, the current on the input side HAS TO go up. Example - if voltage is boosted by 10% on the output, current draw on the input side will go up by 10%. An autoformer can't make power but it can lose a bit.
You are limited to the 30 amps at the pedestal (or 50 amps) and the breakers do not care what the voltage is. So say a 30 amp pedestal was at 100 volts, the most you can draw is 3,000 watts (down from 3600 @ 120 volts). The autoformer will be boosting the output by 10% to 110 volts but will only be able to draw max 27 amps inside the RV (not really a big deal). When an autoformer is in boost mode, you lose available capacity compared to being at 120 volts.
If you had to, I would argue with a CG that if the voltage is low, you draw less power compared to being at the normal 120 volt level so what's the problem... Have fun with that.
Voltage drop in CGs is due either to the NEC min. code requirements that were used at the time of construction or inadequate maintenance of CG wiring. It's usually the former, and older CGs are just not able to keep up with the high demands of today's RVs. Newer campgrounds are wired with loop-fed pedestals with up to 9 sites on a 200 amp feeder and are MUCH less likely to have voltage issues. Older CGs had remote panels around the property often with individual 30 amp (or 50 amp) runs to sites from a remote panel. You may be connected to a #10 wiring run to your site or be on a 200 amp run shared by other users.
In CGS that are predominantly 30 amp pedestals, many 50 amp RVs are often plugged into them and draw more load than the CG would have been designed for. Prior to 2005, only 5% of CGs had to have 50 amp pedestals, after 2005 it was changed to 20% being required. In the 2017 edition of the NEC, CGs are now required to have 40% 50 amp pedestals. This is a HUGE change from prior to 2005. Good luck on finding newly built CGs anywhere. Some owners will have voluntarily built above min. code requirements.
Another thing that comes into play is the demand calculation requirements of the NEC. One 30 amp pedestal has a demand load of 3600 watts and a 50 amp, 9600 watts (now increased to 12,000 in the 2017 NEC). One site only is calculated at 100% and the more sites there are, the lower the demand figure is up to 36 sites or more which is down to 41% total overall. So there could be a case where many newer higher demand RVs using 50/30 adapters are pushing the main service and sub-feeders to the max in an older CG
So, if a CG is maxed out on "normal" demand loads on a busy & hot summer day, the demand at the main service point or a feeder to a CG section could be near it's limit already. Theoretically, if enough sites were using autoformers, a section or entire CG could be taken down. We were in a CG once that was in that predicament and asked everyone to minimize their electrical usage, despite being very hot out. In reality though, I don't think there are really that many autoformers being used. I've only ever seen a small handful of them in our travels.
We bought a used 30 amp Hughes autoformer a few seasons ago for just over $200US after being in a few too many CGs with low voltage. One was so bad, as soon as we plugged into the 30 amp pedestal, our EMS tripped because the voltage went below 104 volts before even turning anything on. If you value voltage sensitive electrical things in your RV you can either find a better site in the CG with good voltage, find another CG or pull out your autoformer. I'd opt for an autoformer every time. If staying in an older CG especially, you can easily have low voltage. It's not a rare occurrence out there. In the beginning I was not in favor of autoformers but now have no problem with them.
I made a 6' extension cord for the autoformer so I can put it under our TT rather than have it sitting at the pedestal.
I have heard of CGs banning the use of autoformers but have never run across one. Have also heard of some CGs banning electric heaters which I don't understand because they don't restrict the use of AC units. I think some CGs have no clue about electrical stuff. Why frown on autoformers and not limit how much electrical things people use in their RVs? We rarely go over 15 amps and can't see another 10% draw from the autoformer causing anyone a problem.
Lastly, the output of resistive appliances (toasters, coffee makers, space heaters, etc.) varies as the square of the voltage. If at 100 volts for ex., the output would be .9 x .9 = 81% of the rating at the nominal 120 volts. It can take longer for toast & coffee and you may not be warm enough inside. One more reason to have good voltage.
The way an autoformer works is simple: power in = power out, minus autoformer internal losses. If voltage is down on the input side and voltage is up on the output side, the current on the input side HAS TO go up. Example - if voltage is boosted by 10% on the output, current draw on the input side will go up by 10%. An autoformer can't make power but it can lose a bit.
You are limited to the 30 amps at the pedestal (or 50 amps) and the breakers do not care what the voltage is. So say a 30 amp pedestal was at 100 volts, the most you can draw is 3,000 watts (down from 3600 @ 120 volts). The autoformer will be boosting the output by 10% to 110 volts but will only be able to draw max 27 amps inside the RV (not really a big deal). When an autoformer is in boost mode, you lose available capacity compared to being at 120 volts.
If you had to, I would argue with a CG that if the voltage is low, you draw less power compared to being at the normal 120 volt level so what's the problem... Have fun with that.
Voltage drop in CGs is due either to the NEC min. code requirements that were used at the time of construction or inadequate maintenance of CG wiring. It's usually the former, and older CGs are just not able to keep up with the high demands of today's RVs. Newer campgrounds are wired with loop-fed pedestals with up to 9 sites on a 200 amp feeder and are MUCH less likely to have voltage issues. Older CGs had remote panels around the property often with individual 30 amp (or 50 amp) runs to sites from a remote panel. You may be connected to a #10 wiring run to your site or be on a 200 amp run shared by other users.
In CGS that are predominantly 30 amp pedestals, many 50 amp RVs are often plugged into them and draw more load than the CG would have been designed for. Prior to 2005, only 5% of CGs had to have 50 amp pedestals, after 2005 it was changed to 20% being required. In the 2017 edition of the NEC, CGs are now required to have 40% 50 amp pedestals. This is a HUGE change from prior to 2005. Good luck on finding newly built CGs anywhere. Some owners will have voluntarily built above min. code requirements.
Another thing that comes into play is the demand calculation requirements of the NEC. One 30 amp pedestal has a demand load of 3600 watts and a 50 amp, 9600 watts (now increased to 12,000 in the 2017 NEC). One site only is calculated at 100% and the more sites there are, the lower the demand figure is up to 36 sites or more which is down to 41% total overall. So there could be a case where many newer higher demand RVs using 50/30 adapters are pushing the main service and sub-feeders to the max in an older CG
So, if a CG is maxed out on "normal" demand loads on a busy & hot summer day, the demand at the main service point or a feeder to a CG section could be near it's limit already. Theoretically, if enough sites were using autoformers, a section or entire CG could be taken down. We were in a CG once that was in that predicament and asked everyone to minimize their electrical usage, despite being very hot out. In reality though, I don't think there are really that many autoformers being used. I've only ever seen a small handful of them in our travels.
We bought a used 30 amp Hughes autoformer a few seasons ago for just over $200US after being in a few too many CGs with low voltage. One was so bad, as soon as we plugged into the 30 amp pedestal, our EMS tripped because the voltage went below 104 volts before even turning anything on. If you value voltage sensitive electrical things in your RV you can either find a better site in the CG with good voltage, find another CG or pull out your autoformer. I'd opt for an autoformer every time. If staying in an older CG especially, you can easily have low voltage. It's not a rare occurrence out there. In the beginning I was not in favor of autoformers but now have no problem with them.
I made a 6' extension cord for the autoformer so I can put it under our TT rather than have it sitting at the pedestal.
I have heard of CGs banning the use of autoformers but have never run across one. Have also heard of some CGs banning electric heaters which I don't understand because they don't restrict the use of AC units. I think some CGs have no clue about electrical stuff. Why frown on autoformers and not limit how much electrical things people use in their RVs? We rarely go over 15 amps and can't see another 10% draw from the autoformer causing anyone a problem.
Lastly, the output of resistive appliances (toasters, coffee makers, space heaters, etc.) varies as the square of the voltage. If at 100 volts for ex., the output would be .9 x .9 = 81% of the rating at the nominal 120 volts. It can take longer for toast & coffee and you may not be warm enough inside. One more reason to have good voltage.
