Mike: Excellent down to earth explanation of the relationship between voltage, amperage & watts. It's a difficult subject for non-electricians to understand. However, this article reminded me of a previous posting a year or so ago, where you said you were going to do a deep dive into the Hughes Autoformers, which boost voltage & lower amperage, to determine if some claims that they rob electricity from nearby campsite pedestals is true or false. Did you ever run those tests? I've used the autoformers for years & when they are working correctly, they are a life saver in low voltage parks. However, my experience with both the 30 amp & 50 amp models over the years has been that they fail frequently. I've had to return both models many times for repair or replacement. But their customer service has been good, as they've always repaired or replaced them for free .
Electricity is often compared to water flowing in a pipe. There can be very big water pipes, but not enough pressure to give us a good shower from a large pipe, maybe just a dribble at the shower head. However, if we use a water pump, we can boost that pressure and get a great shower. Are we stealing water from someone else? Well yes and no, it depends if our pump drops pressure in the big pipe. If the pressure in the big pipe remains the same, we are not stealing water from anyone. An autoformer is like a water pump between the pipe and our RV. And we could use a volt meter to measure voltage (electrical pressure) before using our autoformer and after, if the line voltage is dropping more feeding our autoformer than by not using it, we are reducing the available current for others in the park and then they might get a dribble in the shower where our shower is now great.
Very interesting and informative article, however, why are you referencing voltage in the initial part of your answer? The question pertains to current. As I'm certain you know, RV's that are powered by a 50 amp campground pedestal are still powered inside the RV by 120VAC circuits. The 120 VAC service happens to consist of two 180 degree out of phase conductors, for which the total voltage between the two conductors is 240 VAC, however, very few RV's use the 240 VAC capability of this service. The remainder of your explanation, dealing in Watts, is very good.
Because you can’t discuss transformers without referencing voltage first. Transformers are all about changing voltage by their winding ratio, and the amount of available current is the inverse of the voltage ratio. And 50-amp RVs do indeed have a split-phase 120/240-volt service, but as you note, very few RVs utilize any 240-volt appliances. I do my best explaining it all, but this is a fairly complex subject for casual reading…😁
Is there any kind of test device (something simple) that I can just plug into a 50 amp pedestal that will show me that the pedestal is wired correctly before I hook up the coach?
Be nice also to have it show what the issue is..
If not, Mike how about You designing one, and put me on your list as your first customer…
The best two devices we have for checking a park pedestal power before plugging-in is an EMS, or surge protector with LED lights that indicate wiring faults. The monster EMS that offers the best protection to our RV’s electrical system and us inside the RV is the EMS. From my point of view, there is not one simple affordable device that can plug into the pedestal outlet and indicate all is good. Knowing the wiring is proper tells us nothing about the voltage. So, we also need to plug-in a volt meter that can measure voltage on a single 30-amp leg or double 50-amp legs. There are Bluetooth surge protectors we can read pedestal voltage with a Smartphone, however if the voltage is too high, it could possibly damage a costly Bluetooth surge protector. The EMS within limits, will cut-off when voltage goes too high or too low including checking for correct wiring. The last thing I doubt we will find in any affordable device is detecting a bad ground circuit all the way back the service entrance panel feeding all pedestals on the circuit. Mike would become quite rich designing and affordable plug-in device with that capability. So, the best we can do for now is check for a Hot RV Skin in addition to using an EMS.
Probably my all-time favorite Heinlein book
Mike: Excellent down to earth explanation of the relationship between voltage, amperage & watts. It's a difficult subject for non-electricians to understand. However, this article reminded me of a previous posting a year or so ago, where you said you were going to do a deep dive into the Hughes Autoformers, which boost voltage & lower amperage, to determine if some claims that they rob electricity from nearby campsite pedestals is true or false. Did you ever run those tests? I've used the autoformers for years & when they are working correctly, they are a life saver in low voltage parks. However, my experience with both the 30 amp & 50 amp models over the years has been that they fail frequently. I've had to return both models many times for repair or replacement. But their customer service has been good, as they've always repaired or replaced them for free .
Electricity is often compared to water flowing in a pipe. There can be very big water pipes, but not enough pressure to give us a good shower from a large pipe, maybe just a dribble at the shower head. However, if we use a water pump, we can boost that pressure and get a great shower. Are we stealing water from someone else? Well yes and no, it depends if our pump drops pressure in the big pipe. If the pressure in the big pipe remains the same, we are not stealing water from anyone. An autoformer is like a water pump between the pipe and our RV. And we could use a volt meter to measure voltage (electrical pressure) before using our autoformer and after, if the line voltage is dropping more feeding our autoformer than by not using it, we are reducing the available current for others in the park and then they might get a dribble in the shower where our shower is now great.
The actual Robert Heinlein quote is "There ain't no such thing as a free lunch" or TANSTAAFL! "The Moon is a Harsh Mistress"
Very interesting and informative article, however, why are you referencing voltage in the initial part of your answer? The question pertains to current. As I'm certain you know, RV's that are powered by a 50 amp campground pedestal are still powered inside the RV by 120VAC circuits. The 120 VAC service happens to consist of two 180 degree out of phase conductors, for which the total voltage between the two conductors is 240 VAC, however, very few RV's use the 240 VAC capability of this service. The remainder of your explanation, dealing in Watts, is very good.
Because you can’t discuss transformers without referencing voltage first. Transformers are all about changing voltage by their winding ratio, and the amount of available current is the inverse of the voltage ratio. And 50-amp RVs do indeed have a split-phase 120/240-volt service, but as you note, very few RVs utilize any 240-volt appliances. I do my best explaining it all, but this is a fairly complex subject for casual reading…😁
Mike,
Is there any kind of test device (something simple) that I can just plug into a 50 amp pedestal that will show me that the pedestal is wired correctly before I hook up the coach?
Be nice also to have it show what the issue is..
If not, Mike how about You designing one, and put me on your list as your first customer…
Jim
The best two devices we have for checking a park pedestal power before plugging-in is an EMS, or surge protector with LED lights that indicate wiring faults. The monster EMS that offers the best protection to our RV’s electrical system and us inside the RV is the EMS. From my point of view, there is not one simple affordable device that can plug into the pedestal outlet and indicate all is good. Knowing the wiring is proper tells us nothing about the voltage. So, we also need to plug-in a volt meter that can measure voltage on a single 30-amp leg or double 50-amp legs. There are Bluetooth surge protectors we can read pedestal voltage with a Smartphone, however if the voltage is too high, it could possibly damage a costly Bluetooth surge protector. The EMS within limits, will cut-off when voltage goes too high or too low including checking for correct wiring. The last thing I doubt we will find in any affordable device is detecting a bad ground circuit all the way back the service entrance panel feeding all pedestals on the circuit. Mike would become quite rich designing and affordable plug-in device with that capability. So, the best we can do for now is check for a Hot RV Skin in addition to using an EMS.