50A to 30A dog bone adapter. Or build one?

[Yoda]

From my understanding a 50/30 adapter just passes one leg of the 50 amp power through. Are there any adapters with selectable legs? Reason I ask is last campground had issues with 30A service and I was thinking the 50/30 adapter might have helped, However if it was on the same power leg as the 30 it would not help. Thoughts?

Also who makes a good 50A to 30A adapter?

I had a thought I could build my own if I could find a high enough rated SPDT switch to tie the 2 hot 50A legs too. Hot in each side, but switch would only feed power from one out the middle terminal depending on the up or down switch position, then have a 50 amp plug feed it and a 30A receptacle. All in a waterproof box. 50 and 30 amp neutrals would be tied together separately. But I am probably missing something. Ground wires?

Thanks
Keith

[mpking]

How about this one?

https://amzn.to/38hwMpK

[mpking]

You could also just manually wire one "2nd Phase" and just swap them if you have a problem. That's probably the best solution. (IE, buy a 2nd adaptor, cut it in the middle and swap the hots, and then reseal the sheaf.). If you have a problem, just switch phases.

[Yoda]

How about this one?

https://amzn.to/38hwMpK

Thanks Mike - did not know that existed. The video shows they did split the power legs.

[SolitudeAtLast]

Yoda has a good idea for 30a RVs. And MPKING’s dog one looks good. One would think campground posts would be wired to alternate which leg the 30a is connected to in order to try to balance 30a loads between the 2 legs. But, who knows how the electricians actually did it.

Also, if the post breaker seems to trip too easily, it may be weak. Prior to upgrading to our 50a Solitude, we experienced a weak 30a post breaker with our previous 30a Keystone Premier, which had a power management / surge protection system installed. We had no problems Jan-Mar 2019. Returning in Nov 2019 to the same site with the same camper, we started having the post breaker pop on the 1st day. Watching our volts & amp draw on the display, it was apparent the post breaker was the problem. It was replaced the next day, with no more problems. Breakers do get old & weak. Campground tech told me he has also had brand new breakers that were weak.

I appreciate all the electrical and plumbing know-how available from the Moderators and others on this forum!

Doug

[ncitro]

Thanks Mike - did not know that existed. The video shows they did split the power legs.

I would think that would be your easiest solution. I like the switch idea, but by the time you get the parts and put it together the wye adapter will probably be cheaper.

[tgodrich]

A 30 amp post service provides one hot 115Volt connection to the RV. A 50 amp has two 115 volt connections on separate legs to the RV. Most RV's run some appliances on one leg and some on the other leg to balance the loads a bit. If you were to need 220 volt for something in the RV, the 50 amp plug should be able to supply this as that would be across the two 115V legs. That is assuming the 50 amp post actually has two different phases of the AC power, which is required to get the 220 volts. If they are the same phase, you will only get 115 volts, period. A 30 amp post can supply 30 amps total, not 30 amps to each leg. And a 30 amp post is only 115 volts.

Now on to the existing question. A dogbone, if wired as I understand it and as mine is, essentially splits the 115 volts of the 30 amp plug to both legs of the 50 amp circuit. The net is that the plug can only handle the 30 amps from ALL of your appliances. So, if you have 20 amps in one leg and perhaps 15 amps in the other leg of your 50 amp service, the 30 amp will not work. You will need to not run something to get the amperage down to 30 amps or less.

I have heard of people building switches to try to separate the 30 amp post power into each leg separately. You are still limited to 30 amps, no matter how you slice it. Knowing which appliances are on each leg will help you manage your amp load. Instead of getting switches, etc., simply do not use all your heavy current (amperage) items at the same time. Shut off the AC to run the microwave, etc., then turn the AC back on when finished. If the AC is already running, you might be able to do the microwave too as the running current in the AC is lower than the start up current.

High current items that will add up quickly are: Each AC unit. (If you have two, that is a heavy load just by itself.) A fire place, refrigerator (on AC power), hot water heater (on electric power), and a microwave. Washer and dryer will also be heavy loads. If you run portable items like a hair dryer, that will draw a lot of current too. You kind of have to manage your power, and even more so if you are using one of the 30 amp dogbones.

Remember, a 30 amp service can only supply 30 amps, even it plugged into your 50 amp trailer with a dogbone adapter.

Also note... I have used a 50' extension cord to run my AC in the trailer. Of concern here is voltage drop through the cord. A good 12 gauge cord would be best, but these are expensive. 14 gauge would probably work too, but as your gauge gets smaller (higher number is smaller wire) you will begin to have more voltage drop, and the cord will likely get warm as well. This can present a fire hazard. I generally will not try running the AC through 20 amp or 15 amp extension cords. I do have a dogbone that is 20 amp to my trailer 50 amp, but this is just to allow me to suppy shore power to the trailer for lights, and other low current (low amp) items and to keep the batteries charged.

Popping (tripping) the 30 amp post circuit breaker can occur if the post voltage is reduced (like when everyone in the RV park has their AC on), OR running too many appliances at once, OR a faulty post breaker. As the circuit breakers wear out, they can tend to trip more often. You kind of have to diagnose the problem a bit. Some of the surge / voltage protectors (the more expensive ones usually) allow you to monitor the post voltage and some even allow you to monitor the current load you have. A good investment in my opinion.

Hope this helps a bit.

[ncitro]

A 30 amp post service provides one hot 115Volt connection to the RV. A 50 amp has two 115 volt connections on separate legs to the RV. Most RV's run some appliances on one leg and some on the other leg to balance the loads a bit. If you were to need 220 volt for something in the RV, the 50 amp plug should be able to supply this as that would be across the two 115V legs. That is assuming the 50 amp post actually has two different phases of the AC power, which is required to get the 220 volts. If they are the same phase, you will only get 115 volts, period. A 30 amp post can supply 30 amps total, not 30 amps to each leg. And a 30 amp post is only 115 volts.

Now on to the existing question. A dogbone, if wired as I understand it and as mine is, essentially splits the 115 volts of the 30 amp plug to both legs of the 50 amp circuit. The net is that the plug can only handle the 30 amps from ALL of your appliances. So, if you have 20 amps in one leg and perhaps 15 amps in the other leg of your 50 amp service, the 30 amp will not work. You will need to not run something to get the amperage down to 30 amps or less.

I have heard of people building switches to try to separate the 30 amp post power into each leg separately. You are still limited to 30 amps, no matter how you slice it. Knowing which appliances are on each leg will help you manage your amp load. Instead of getting switches, etc., simply do not use all your heavy current (amperage) items at the same time. Shut off the AC to run the microwave, etc., then turn the AC back on when finished. If the AC is already running, you might be able to do the microwave too as the running current in the AC is lower than the start up current.

High current items that will add up quickly are: Each AC unit. (If you have two, that is a heavy load just by itself.) A fire place, refrigerator (on AC power), hot water heater (on electric power), and a microwave. Washer and dryer will also be heavy loads. If you run portable items like a hair dryer, that will draw a lot of current too. You kind of have to manage your power, and even more so if you are using one of the 30 amp dogbones.

Remember, a 30 amp service can only supply 30 amps, even it plugged into your 50 amp trailer with a dogbone adapter.

Also note... I have used a 50' extension cord to run my AC in the trailer. Of concern here is voltage drop through the cord. A good 12 gauge cord would be best, but these are expensive. 14 gauge would probably work too, but as your gauge gets smaller (higher number is smaller wire) you will begin to have more voltage drop, and the cord will likely get warm as well. This can present a fire hazard. I generally will not try running the AC through 20 amp or 15 amp extension cords. I do have a dogbone that is 20 amp to my trailer 50 amp, but this is just to allow me to suppy shore power to the trailer for lights, and other low current (low amp) items and to keep the batteries charged.

Popping (tripping) the 30 amp post circuit breaker can occur if the post voltage is reduced (like when everyone in the RV park has their AC on), OR running too many appliances at once, OR a faulty post breaker. As the circuit breakers wear out, they can tend to trip more often. You kind of have to diagnose the problem a bit. Some of the surge / voltage protectors (the more expensive ones usually) allow you to monitor the post voltage and some even allow you to monitor the current load you have. A good investment in my opinion.

Hope this helps a bit.

Yeah I think the problem Yoda had was low voltage in the park, but it was better on one phase than the other. Since his rig is only 30 amps, he would like a 50 amp to 30 amp dog bone that allows him to select which of the two phases is used to feed the 30A "outlet" of the dog bone. The one with two 30A outlets would accomplish this as he could plug into one outlet, check the voltage, unplug and plug into the other and take whichever has better voltage.

[tgodrich]

That makes sense. I have not dealt with 30 amp trailers since my toy hauler. Never drew enough current to worry about which leg to use on a 50 amp post with that trailer.

When I connect my trailer now (50 amp) quite a few of the parks only have 30 amp available. So I have a really heavy duty 8 gauge 30 amp extension cord I use to connect the trailer. I put the dog bone adapter on the trailer that converts from 30 amp to the 50 amp plug GD uses. I have the cheaper surge protector (a gift) that is sacrificial, and does not indicate voltage or current, so I measure post voltage with my DVM before I hook up. If this surge protector gets blown, the whole thing has to be replaced. At that point, I will upgrade to one that monitors both voltage and current on both legs.

[Scott'n'Wendy]

I'm thinking you will be preparing for a very rare condition. Like, you will probably not see it again. I never have in the last 25 years.
But, if you like to be prepared for anything...

[ncitro]

I'm thinking you will be preparing for a very rare condition. Like, you will probably not see it again. I never have in the last 25 years.
But, if you like to be prepared for anything...

I know when I see low voltage on a pedestal its frequently significantly lower on one phase. I have always assumed these parks did a poor job of balancing their 30 amp circuits and put them consistently on the same phase when wiring the pedestals. I definitely could see the benefit of this.

Another option Yoda is to set your power assist lower than 30 amps at say 15 or 20, so the inverter goes into power assist sooner and helps eat up some of the load. Obviously if you do that you would need to watch your batteries.

[Yoda]

I know when I see low voltage on a pedestal its frequently significantly lower on one phase. I have always assumed these parks did a poor job of balancing their 30 amp circuits and put them consistently on the same phase when wiring the pedestals. I definitely could see the benefit of this.

Another option Yoda is to set your power assist lower than 30 amps at say 15 or 20, so the inverter goes into power assist sooner and helps eat up some of the load. Obviously if you do that you would need to watch your batteries.

Thanks Neil

I have some long eithernet extension cords ordered to tie to the trailer so I can reprogram (roughly 200' ) From my desktop.. Originally I did not want the power assist. Now thinking that with a soft start set up it might be a good idea..My Progressive industries surge protector did its job shutting down due to low voltage .Pedistal breaker never tripped..

I just need to get the system stable and reliable for now. A bit of tweaking. This was the real first shake down trip for the trailer. Some issues I will post about later, but overall OK.

I am re-thinking my decision on the Crowns before the Alaska trip, but need to keep SWMBO happy. If I can get the low voltage inverter problem solved and tweak the charge profile I should be OK, but right now system is dropping to 90% SOC before the MPPT's kick in fully. They tend to stay at float/storage.

I am in the process of ordering a new truck with her permission and blessing. I am considering the max alternator possible ( is dual the best option) so will be researching the DC to DC system. All in progress. Good thing I have friends like you to keep me from the dark side.

Someday I hope we meet up
Keith

[ncitro]

Thanks Neil

I have some long eithernet extension cords ordered to tie to the trailer so I can reprogram (roughly 200' ) From my desktop.. Originally I did not want the power assist. Now thinking that with a soft start set up it might be a good idea..My Progressive industries surge protector did its job shutting down due to low voltage .Pedistal breaker never tripped..

I just need to get the system stable and reliable for now. A bit of tweaking. This was the real first shake down trip for the trailer. Some issues I will post about later, but overall OK.

I am re-thinking my decision on the Crowns before the Alaska trip, but need to keep SWMBO happy. If I can get the low voltage inverter problem solved and tweak the charge profile I should be OK, but right now system is dropping to 90% SOC before the MPPT's kick in fully. They tend to stay at float/storage.

I am in the process of ordering a new truck with her permission and blessing. I am considering the max alternator possible ( is dual the best option) so will be researching the DC to DC system. All in progress. Good thing I have friends like you to keep me from the dark side.

Someday I hope we meet up
Keith

No problem at all. On the Ford side I'm pretty sure the biggest option is dual. I know mine spins up my 40 amp DC to DC charger with no problem. It's a great addition particularly on rainy travel days, allows us a couple Walmart days in a row with no issue.

Power assist has been great for me but I'm not sure it would have helped in your case. It's more meant for running the rig on a circuit that's less than an ideal breaker, say 30 (in my case) or 15 (for you). If you wanted to run your ac and water heater on electric, it would pick up the difference if both were on at once, and recharge when they cycled off (or make it up with solar).

Low voltage is a serious problem (particularly in hot weather when you need ac) and the only solutions are either a autoformer, or trying the other phase as you suggested.