Permanently Mounting Hughes AutoFormer Underneath Travel Trailer

[GlowPlug]

Can the 50 amp Hughes AutoFormer be permanently mounted on the underside of travel trailer. Found a possible location at front of trailer, it's behind the rock guard panel and the unit will mount along the driver side of trailer in the corner up against rock guard panel.
As long as it's a water tight location, can the Hughes handle being mounted full time under trailer.
Can it take the bumps and jarring that comes into play while traveling down the road.


Remember, any Day on this side of the Grass is such a Great Time. And with that, Go Out and have a Good Day on purpose.
Gary

[cavie]

Originally Posted by GlowPlug

Can the 50 amp Hughes AutoFormer be permanently mounted on the underside of travel trailer. Found a possible location at front of trailer, it's behind the rock guard panel and the unit will mount along the driver side of trailer in the corner up against rock guard panel.
As long as it's a water tight location, can the Hughes handle being mounted full time under trailer.
Can it take the bumps and jarring that comes into play while traveling down the road.


Remember, any Day on this side of the Grass is such a Great Time. And with that, Go Out and have a Good Day on purpose.
Gary

I don't think it is designed for that. Also, If you are also using an EMS the autoformer needs to be in front of the EMS. Otherwise the EMS can shut off the autoformer and your electricity.

[NXR]

As long as it's a water tight location, can the Hughes handle being mounted full time under trailer.

Can it take the bumps and jarring that comes into play while traveling down the road?

Yes. Hughes makes an internal mounting kit which really is a way to have it mounted inside but able to be removed without rewiring. They provide nothing to actually mount it.

Some people have built their own kit using an electric dryer cord but those cords do not have the same gauge wire.

I have mine permanently mounted in a compartment. As long as it’s mechanically supported and protected from moisture there is no difference between mounting it and just carrying it in a box while you’re driving, right?

Ray

[cavie]

Originally Posted by NXR

Yes. Hughes makes an internal mounting kit which really is a way to have it mounted inside but able to be removed without rewiring. They provide nothing to actually mount it.

Some people have built their own kit using an electric dryer cord but those cords do not have the same gauge wire.

I have mine permanently mounted in a compartment. As long as it’s mechanically supported and protected from moisture there is no difference between mounting it and just carrying it in a box while you’re driving, right?

Ray

The Dryer cords are the exact #10 wire ga as an RV 30 amp cord. The plugs are different and will not plug in to each other.

[NXR]

Originally Posted by cavie

The Dryer cords are the exact #10 wire ga as an RV 30 amp cord. The plugs are different and will not plug in to each other.

OK but...the OP said he was using a 50-amp Autoformer, not 30. And in keeping with your tagline I wrote “cord” which means “wire”.

They’re cutting the dryer plug off and adding their own plug.

So I guess you’re actually agreeing with what I wrote?

Ray

[cavie]

OK. If someone was to rewire in that fashion Why would they not use a Range cord that has the proper 50 amp #8 ga wire in it and change those plugs??

The better question is way would someone not just buy 3' of #8/3 with ground and buy the proper plugs that fit the 50 RV service

Why would anyone put 30 amp wire on a 50 amp service

I was referring to your "Some people" post. Not the OP's 50 amp post.

[NXR]

Touché.

While I may be semi-qualified to talk on many subjects, I am in no way qualified to talk on why humans sometimes do what they do.

As painful as it was to my wallet, I paid the $90 and bought the 6-gauge pigtail from Hughes. It has a 6-gauge neutral wire, apparently unlike the dryer and range wires.

I had read that the neutral for a 240 VAC appliance is permitted to have a smaller gauge because it's not expected to carry any current normally. Is that accurate?

Ray

[DouglasReid]

Originally Posted by NXR

Touché.

While I may be semi-qualified to talk on many subjects, I am in no way qualified to talk on why humans sometimes do what they do.

As painful as it was to my wallet, I paid the $90 and bought the 6-gauge pigtail from Hughes. It has a 6-gauge neutral wire, apparently unlike the dryer and range wires.

I had read that the neutral for a 240 VAC appliance is permitted to have a smaller gauge because it's not expected to carry any current normally. Is that accurate?

Ray

The Neutral wire on the range cord s the same 6 gauge wire as the two hot leads, the Ground wire is smaller though

[NXR]

Originally Posted by DouglasReid

The Neutral wire on the range cord is the same 6 gauge wire as the two hot leads, the Ground wire is smaller though

This may be a caveat emptor subject.

https://www.homedepot.com/p/Eastman-...1246/301074794

Connects to a 4-prong receptacle
50 Amp - 125 / 250 V
2 - 6-gauge wires / 2 - 8-gauge wires
UL Listed

Ray

[TitanMike]

Originally Posted by GlowPlug

Can the 50 amp Hughes AutoFormer be permanently mounted on the underside of travel trailer. Found a possible location at front of trailer, it's behind the rock guard panel and the unit will mount along the driver side of trailer in the corner up against rock guard panel.
As long as it's a water tight location, can the Hughes handle being mounted full time under trailer.
Can it take the bumps and jarring that comes into play while traveling down the road.


Remember, any Day on this side of the Grass is such a Great Time. And with that, Go Out and have a Good Day on purpose.
Gary

To me a "water tight" compartment also means "NO VENTILATION" which could lead to an undesirable build up of heat.

In my part of the country where driving in the rain is almost more common than driving in sunshine, underneath a trailer wouldn't be my first choice.

[Larry-NC]

Originally Posted by NXR

This may be a caveat emptor subject.

https://www.homedepot.com/p/Eastman-...1246/301074794

Connects to a 4-prong receptacle
50 Amp - 125 / 250 V
2 - 6-gauge wires / 2 - 8-gauge wires
UL Listed

Ray

Ah, the so-called "split-phase connection." When you take two hot lines from a panel that have 240Vac between them, and use them as two 120Vac lines to the common neutral, current in the neutral equals the difference in the two hot lines. (Electrical engineers call this a two-phase service. Electricians have not been taught this terminology and don't like it. Some of them call it split-phase.) Because the two hot lines are 180 degrees out of phase, if:

• Both hot lines drawing 10 amps each, neutral current is 0.
• Both hot lines drawing 25 amps each, neutral current is 0.
• Both hot lines drawing 50 amps each, neutral current is 0.
• One hot line drawing 20 amps, the other drawing 10 amps, neutral current is 10.
• One hot line drawing 25 amps, the other drawing 5 amps, neutral current is 20.
• One hot line drawing 50 amps, the other drawing 0 amps, neutral current is 50. <=== This is a problem.

The cord referenced above works fine in a range or dryer, where most of the current is consumed by the 240 Vac heating elements and the only imbalance between the two hots is maybe a 120Vac light bulb or clock motor. They can safely use the undersized neutral as in the first examples quoted above.

But an RV is a different situation. The load is composed of a bunch of separately-controlled individual items. It could be possible to have a load like the last element in the list above. In that case, excessive current would be flowing through an undersized neutral, 8 gauge when it should have been 6 gauge.

One sample situation is where one side of the 50 amp cord, plug, pedestal, or breaker itself opens. All the appliances on the other side keep running and overload the undersized neutral which overheats and burns up the trailer. A good electrical installation will fail safe. This one won't.

(Always like to see Cavie's comments.)

[NXR]

I don't understand how the current in the neutral in a 50-amp RV could ever be zero because in a series circuit the current is identical in each leg.

Either end of the transformer winding to the neutral (which is just the transformer center tap) is a series circuit and those center-tapped transformers power the 240 VAC 50-amp source.

So when a 240 VAC center-tapped transformer is the source of the power, where the center tap is always the neutral, the current flowing in one end leg of the transformer must be equal to the current in the center tap (a.k.a. neutral) for all 120 VAC usage.

I get that the currents are flowing out phase but in this case:

Both hot lines drawing 50 amps each, neutral current is 0.

That's the same as an open neutral, right? If there is no current flow then the wire does not need to be there because there also is no potential difference.

2-phase power used two phases 90 degrees apart or so I was taught. That was a very early AC generation system.

Ray

[Dirt Sifter]

gawd, I love this site.

[GlowPlug]

OK guys here is my issue on mounting the 50 amp Hughes AutoFormer.
The only outside storage compartment I have on trailer is located under the mattress platform in bedroom and the bedroom has a slide out. Just noway to make that outside compartment work.

Inside trailer I have a interior cabinet that is perfect for the Hughes unit. Right below cabinet is the breaker box and to left of that is the fireplace.
I pulled fireplace and Hardwired the PI EMS 50 amp unit behind fireplace. I can wire in the Hughes AutoFormer by drilling two holes in the side of cabinet that I would like to use and running the input and output wiring down behind to the breaker panel below and then the Hughes will be hardwired inline first followed by the PI Ems that I already have wired in.

This is my concern, Should I be worried about the Hughes blowing up in the middle of night and catching the inside of trailer on fire. Can the Hughes unit Blow Up after a lighting strike. Will it send smoke all over inside of trailer.

Understand when the Hughes unit is having to work that it emits lots of Heat.How will I deal with that heat being inside trailer. This is all located in the center of kitchen and living area and the middle of trailer.
How would that work inside trailer using that inside cabinet. This cabinet that the Hughes unit would be mounted in is about 24 inches wide by about 48" tall and like I said it's located right above breaker panel and to the left of the fireplace.

That's the reason I wanted to mount the Hughes unit outside to stay away from a fire and smoke hazard.

Thanks for the help in advance.
Gary

[B and B]

Considering the most recent National Electrical Code rules state that Autotransformer are not to used any longer. Illegal.

Mike Sokol thread on Facebook discusses it all.


https://www.facebook.com/groups/rvel...epa=SEARCH_BOX

[Larry-NC]

Ray, you're missing a couple of points here. Let's go paragraph by paragraph.

Originally Posted by NXR

2-phase power used two phases 90 degrees apart or so I was taught. That was a very early AC generation system.

No. The two phases are 180 degrees apart.

In a two-phase circuit, the two phases are offset by 180 degrees, not 90. That means that just as one phase peaks at positive 170 volts, the other peaks at negative 170 volts. If you drew graphs (or oscilloscope) of the two points with respect to the center tap, they would be mirror images of each other. (120 volts is the average over a cycle, equivalent to 120 volts DC, but 170 is the peak.)

Originally Posted by NXR

I don't understand how the current in the neutral in a 50-amp RV could ever be zero because in a series circuit the current is identical in each leg.

This is not A series circuit. It is actually TWO series circuits.

Originally Posted by NXR

I don't understand how the current in the neutral in a 50-amp RV could ever be zero because in a series circuit the current is identical in each leg.

So if you look at what's going on in the center-tapped winding, current is going into one end of the transformer and going out of the other--just as you said. Now, let's look at what happens when we connect two separate loads to the center tap of the transformer at the instant when the ends are at their peaks. One load is across the center tap and one end tap. The other load is across the center tap and the other end tap.

Maybe visualize the winding vertically. The bottom end is at -170 v. The center tap is at 0. The top end is at +170. For now, assume the loads are equal. We will use the convention that current in a load flows from the more-positive terminal to the less-positive terminal (the same convention Benjamin Franklin used).

Load 1(bottom)
Current flows out of the center tap (0 v) through the load to the bottom tap (-170v).
Load 1(top)
Current flows out of the top tap (+170 v) through the load into the center tap (0v).

Did you get that? Since the loads are equal, the currents are equal. And we have equal current going into and out of the center tap. That adds to zero current.

And now, by simple extension, if we change the loads so one draws a little more current than the other, then the only current flowing in the center tap is the difference.

Originally Posted by NXR

Either end of the transformer winding to the neutral (which is just the transformer center tap) is a series circuit and those center-tapped transformers power the 240 VAC 50-amp source.

So when a 240 VAC center-tapped transformer is the source of the power, where the center tap is always the neutral, the current flowing in one end leg of the transformer must be equal to the current in the center tap (a.k.a. neutral) for all 120 VAC usage.

You're deceiving yourself by thinking of this as a 240v circuit. It's easier to understand this by thinking of it as two 120v circuits. In fact, within a trailer there are generally NO 240v appliances. (The exception is the dryer in a few high-end models.)

Originally Posted by NXR

I get that the currents are flowing out phase but in this case:

Both hot lines drawing 50 amps each, neutral current is 0.

But the currents into the center tap (neutral) are going in opposite directions because the center tap is positive with respect to the bottom tap, but negative with respect to the top tap. Equal currents in opposite direction add to zero current.

Originally Posted by NXR

That's the same as an open neutral, right? If there is no current flow then the wire does not need to be there because there also is no potential difference.

If the loads on each of the two separate individual circuits were exactly equal, there would be no current in the neutral. That's the case in an residential air conditioner or range where (most of) the loads are across 240 volts. But in a trailer, the 120v microwave on one circuit doesn't match the 120v water heater on the other circuit, for example. The neutral does carry current (the difference) and does need to be there.

What if you walked into the trailer with everything off and turned on only one air conditioner? You would have 14-15 amps through one end tap and the neutral and nothing through the other one.

Ray, I', caregiving DW tonight and don't have time to draw pictures now. If this isn't clear, I'll try to draw some later this week.

Larry
BSEE University of Illinois, 1968
MSEE New Mexico State University, 1973
MSCS North Carolina State University, 1995

[NXR]

Do you have the Autoformer yet?

They do not emit a lot of heat but they cannot be closed up inside a small compartment. In fact, their metal case is completely riveted shut without ventilation slots. That's why they are water-resistant but not waterproof. I think their maximum rated loss is 1 amp so at most they would generate two or three hundred watts of heat. Definitely not insignificant but obviously that heat can be carried away by convection and forced air ventilation is not needed.

https://hughesautoformers.com/autofo...-does-it-work/

"An Autoformer running at full output (50amps) will use 1 amp, but will cause appliances to cycle more often and run cooler."


https://hughesautoformers.com/autofo...on-procedures/

"Although not preferred, you can lay the Autoformer on its side to place into a well- ventilated compartment."

"The small holes below the cord and plug are for condensation drainage. Please ensure that these remain open and are not blocked in any way."

"Do not set upside down or use it for any purpose other than intended. Do not seal holes or edges with silicone or any other material."


If the Autoformer catches fire internally it will be self-contained inside the metal box. I have never heard or ever read of that happening. The only way the fire could escape the metal box is if it ignited the wiring or got the metal box so hot that it ignited the surrounding cabinet. There is not a lot of oxygen inside that metal box to support sustained combustion.

You already have a PI EMS with surge protection and it's in a plastic case. If the Autoformer was not there then the PI EMS would take the hit from a surge or lightning strike. Any fire danger would be a lot worse from a plastic-cased device.

While the older Autoformers always provided a slight boost, 2% I think, the current production units do not, so they do nothing until needed.

All surge protection units are simply an electronic component called a metal oxide varistor or MOV. The MOV internally, rapidly, and momentarily short circuits the surge voltage and then resets. It's a solid state device so there are no moving parts.

Each MOV is rated at XX joules. If you want 3 XX joules of surge protection you just connect up three MOVs. Easy peasy.

Manufacturers add surge protection to their EMS, their auto transfer switch, their Autoformer, whatever, simply by adding some MOV devices inside.


So if your cabinet is ventilated somehow since it is 48" tall it should be fine. If nothing else, consider adding a grill to the bottom of the cabinet and to the top to let cooler floor air draw in at the bottom and vent heat out the top. I don't know your layout but you just want a way for heat to not build up in the cabinet.

Plus with the obvious caveat of not piling clothes or anything else on or around the Autoformer that could insulate it and cause it to heat up. If that is a possibility go buy some perforated metal and build a small cage around it to assure it always has free air space.

My 50-amp Autoformer has been powered up for five weeks and the two air conditioners and/or their fans run 24x7. It is warm to the touch in the outside compartment but the converter, PI EMS, inverter and transfer switch are all in the same compartment. The 70-amp converter is the big heat generator and it warms up the other stuff in that compartment. The power here is very good and stable so I think the Autoformer has just been idling all the time. When we have been at a campground with low voltage, that condition has never been present more than an hour or so.

HTH,

Ray

[Larry-NC]

Originally Posted by GlowPlug

OK guys here is my issue on mounting the 50 amp Hughes AutoFormer.
The only outside storage compartment I have on trailer is located under the mattress platform in bedroom and the bedroom has a slide out. Just noway to make that outside compartment work.

Inside trailer I have a interior cabinet that is perfect for the Hughes unit. Right below cabinet is the breaker box and to left of that is the fireplace.
I pulled fireplace and Hardwired the PI EMS 50 amp unit behind fireplace. I can wire in the Hughes AutoFormer by drilling two holes in the side of cabinet that I would like to use and running the input and output wiring down behind to the breaker panel below and then the Hughes will be hardwired inline first followed by the PI Ems that I already have wired in.

This is my concern, Should I be worried about the Hughes blowing up in the middle of night and catching the inside of trailer on fire. Can the Hughes unit Blow Up after a lighting strike. Will it send smoke all over inside of trailer.

Understand when the Hughes unit is having to work that it emits lots of Heat.How will I deal with that heat being inside trailer. This is all located in the center of kitchen and living area and the middle of trailer.
How would that work inside trailer using that inside cabinet. This cabinet that the Hughes unit would be mounted in is about 24 inches wide by about 48" tall and like I said it's located right above breaker panel and to the left of the fireplace.

That's the reason I wanted to mount the Hughes unit outside to stay away from a fire and smoke hazard.

Thanks for the help in advance.
Gary

Locating the autoformer under the trailer is no less a fire hazard than locating it inside the trailer. The bottom side of the plywood floor is no more fire-resistant than the top side.

Underneath is even worse if you have one of those sandwich floors with styrofoam in the middle. The fumes of burning styrofoam are toxic.

[NXR]

Originally Posted by B and B

Considering the most recent National Electrical Code rules state that Autotransformer are not to used any longer. Illegal.

Mike Sokol thread on Facebook discusses it all.

https://www.facebook.com/groups/rvel...epa=SEARCH_BOX

That absolutely is not correct.

First off, the National Electrical Code is neither "national" nor a "code" (law). It is a recommendation by the National Fire Protection Association with a catchy name. That being said, it is followed in full or in part by most jurisdictions somehow.

For the NEC revisions to become law, the jurisdiction having authority must legislatively adopt them. Many jurisdictions (cities, counties, townships, whatever) make a conscious decision to stay one revision back because they simply do not have the manpower in their building departments to rapidly review all changes and to create an impact analysis on their area. And because most changes are essentially fine-tuning nowadays, not brand new concepts.

Secondly, the jurisdiction having authority has the full right to adopt any part of the NEC, modify any part of the NEC, disregard any part of the NEC or totally and completely ignore the NEC in order to better suit their local needs.

The first paragraph of this article may help people understand this: https://en.wikipedia.org/wiki/National_Electrical_Code

The article does gloss over the legal tenet of sovereign immunity when discussing civil lawsuits so take that part with a grain of salt.

Ray

[cavie]

Originally Posted by NXR

Touché.

While I may be semi-qualified to talk on many subjects, I am in no way qualified to talk on why humans sometimes do what they do.

As painful as it was to my wallet, I paid the $90 and bought the 6-gauge pigtail from Hughes. It has a 6-gauge neutral wire, apparently unlike the dryer and range wires.

I had read that the neutral for a 240 VAC appliance is permitted to have a smaller gauge because it's not expected to carry any current normally. Is that accurate?

Ray

Yes this is true. but it is expected to carry current. Just not All of it.