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Sal

Dogbone versus flat adapter

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Hey all! I know very little about the electrical workings in my RV. In fact, we lost power the other day and after I exhausted my knowledge (checking the breakers) I was glad that the whole camp was out of power because I would have had no idea what to do next. 

Anyway, that isn't my question. We will be parking in a family's driveway for the holidays. We have a 50amp Class rig and already have a 50 to 30 adapter as well as a 30 to 15 adapter. If I want to plug in to have a little more comforts (run the tv, maybe run our space heater) will I blow everything up? (I told you I know nothing) 

I had it in my mind that a 50 to 30 amp dogbone might be safer for some reason so I thought I would ask. 

Any tips or pointers? I suppose if nothing works, we can just run an outdoor cord in through a window and move the power strip around to power different things. 

Thanks and Happy Holidays!!

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The tv should be fine.

Your space heater may or may not pop the 15 A breaker it is plugged into at your family member's home.  Even a small heater takes a LOT of juice.  Same with a microwave and sometimes a coffee maker. 

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If you are plugged into a standard 15 amp household receptacle, you will not be able to run many things in your coach.  It is safe to do with the 50 to 30 and 30 to 15 adapters you have however.  I'm not sure what type of rig you have, but there are a few things that are always drawing power when you plug into shore power.  The big ones are your converter (or the charger in your inverter if you have one of these instead), the electric side of an RV refrigerator and the electric side of an RV water heater.  All of these can be turned off so they are not drawing power, which will allow you to run other things in the coach.  Just realize, if you turn off the converter, you will not be charging your batteries while plugged in.  You could turn the converter off at the breaker panel in your RV while you are using other things (to conserve power) and then turn it back on when you go to sleep to recharge the batteries over night.  This will help you not try to draw too much power from the residential 15 amp receptacle.

If you have portable electric heaters, I would not try to run them through the RV's electrical system while plugged into a 15 am residential receptacle.  If you need heat in the RV, run the furnace instead.  It doesn't draw any 110 power and won't tax the receptacle you are plugged into at the house.

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If you need heat in the RV, run the furnace instead.  It doesn't draw any 110 power and won't tax the receptacle you are plugged into at the house.

This is only true if you have the converter/charger turned off. If the charger is on it will be trying to keep the batteries charged as the furnace fan (which draws a fair amount of 12 volt power) draws down the battery bank..

Here are some power draw examples from our coach: Electric water heater element- 13 amps, Converter - up to 5 amps, electric refrigerator element - 3 amps, 1500 watt space heater - 12.5 amps, space heater on low - 6 amps, 1000 watt microwave - 8 amps.

My suggestion is that if you can access two 15 amp house hold receptacles on different circuit breakers, use the dogbone to plug in the RV and run a heavy duty extension cord into the RV to power the space heater on low. 

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5 minutes ago, trailertraveler said:

My suggestion is that if you can access two 15 amp house hold receptacles on different circuit breakers, use the dogbone to plug in the RV and run a heavy duty extension cord into the RV to power the space heater on low. 

x2

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3 minutes ago, trailertraveler said:

This is only true if you have the converter/charger turned off. If the charger is on it will be trying to keep the batteries charged as the furnace fan (which draws a fair amount of 12 volt power) draws down the battery bank..

Here are some power draw examples from our coach: Electric water heater element- 13 amps, Converter - up to 5 amps, electric refrigerator element - 3 amps, 1500 watt space heater - 12.5 amps, space heater on low - 6 amps, 1000 watt microwave - 8 amps.

My suggestion is that if you can access two 15 amp house hold receptacles on different circuit breakers, use the dogbone to plug in the RV and run a heavy duty extension cord into the RV to power the space heater on low. 

What trailertraveler says about the converter/charger trying to keep up with 12 volt loads is true.  This is why I suggested turning the converter off when the trailer is being used for other things (like watching TV, running the microwave, etc) and then turning it back on a night while you sleep.  There shouldn't be any 120 volt electrical loads while you sleep (other than the converter and minor loads for entertainment center and microwave standby draws).  If you need to run the furnace while you sleep, the converter should be able to keep up with this battery draw with nothing else on.

His examples are good ideas on what things draw.  I also like the suggestion of using a separate extension cord into another household receptacle on a different circuit in the house to run an electric heater in the trailer.  This may be difficult to find a receptacle on a separate circuit in the house that is reachable.  The extension cord also needs to be of sufficient gauge wire to handle the load of an electric heater.

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5 hours ago, Sal said:

I had it in my mind that a 50 to 30 amp dogbone might be safer for some reason so I thought I would ask. 

This is generally true because the adapters that just fit on the power plug are nearly always very cheaply made and could overheat and cause a new set of problems. 

5 hours ago, Sal said:

If I want to plug in to have a little more comforts (run the tv, maybe run our space heater) will I blow everything up?

There are several things which could happen or perhaps nothing at all. The key thing to remember is that you will be limited to less than 15a of total power. I would not turn off the converter to the battery as it should be able to keep up with the load from the furnace blower as I have done that many times of the years we have been RV owners. The converter will draw somewhere around 5a of 120V power to keep the furnace blower happy and the batteries charged. You can probably also use the TV but no way the microwave and no electric heater. That heater alone will draw about 13a or if on low power perhaps 8a.  The idea of using a separate extension cord to power an electric heater from a separate outlet that is on a different circuit from the one your RV is plugged into would work if you can find a way to run that cord inside of the RV without losing too much heat through the opening for the cord. It will be important to make sure that the two cords are supplied by different house circuit breakers. 

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That extension cord should be at least 12 gauge wire if you want to run the heater on high.  Even then it may get a little warm.

Lenp

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Thanks everyone! Tons of great info here. 

We always run our electric heater on low so that part shouldn't be a problem. 

It seems unanimous that I need the dogbone. We shouldn't need our microwave for anything. Just outlets, tv and the possibility of heat so we don't freeze! 

Thanks all!

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We have had times where we were plugged into a relative's 15 amp outlet while in their driveway in the winter, and were able to use all our 12 volt systems.  We turned the fridge and water heater to gas only, did not use the microwave or any other high load 120 volt circuits.  We were able to use our 120 volt TV, and never had a problem with maintaining our batteries with the converter.  Just make sure any adapters you use are in excellent condition, check occasionally that they are not getting hot, and you will be OK.

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Thought I would update the thread.

I ended up getting the 50-15 dogbone. We've been very careful about our energy consumption but so far so good. The moment we pulled in I unplugged the microwave and coffee maker so we wouldn't even be tempted. We've been going pretty well operating on the rule of one thing at a time. If we have dehumidifier plugged in we'll unplug the heater etc. 

I just got brave enough to use the airfryer, but I turned everything else off first. 

So, while it isn't the best (a little cold) it isn't undoable. Though, I knew we didn't need much, just an occasional plug for a laptop and a heater now and then. 

Thanks all for the help!!

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11 hours ago, Sal said:

So, while it isn't the best (a little cold) it isn't undoable.

It is a learning process and even in cases like this, the actual result will depend partly on the people who occupy the RV. If you should trip a circuit breaker, that isn't a disaster unless it is the middle of the night and you can't find the breaker. Just carefully note what was in use at the time the breaker opens and you will soon figure it out. With heating, the key is just how much heat you need. 

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7 hours ago, NoDirectionHome said:

Does your family's home have a 30A/230V dryer plug you could tap into?

That would be a good way to create an electrical disaster if they don't know what they are doing. 

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34 minutes ago, Kirk Wood said:

That would be a good way to create an electrical disaster if they don't know what they are doing. 

Kirk, I know you're pretty electrically astute, but how would that be any different than plugging into the power pole at a campground?

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39 minutes ago, NoDirectionHome said:

Kirk, I know you're pretty electrically astute, but how would that be any different than plugging into the power pole at a campground?

First of all, no RV has a plug that will fit into the 3 pin style of 240V outlet, if that is what you are thinking of and which is the typical 30a/240V outlet.  The power plug in the campground is 30a/120V and while it may look similar it is not the same. The first picture is on the typical RV power panel.

industrial-switches-and-outlets.jpgimages?q=tbn:ANd9GcS2Q3cqW5nMA-o_MyfITU-

The second picture is a dryer outlet. The dryer outlet supplies 30a but at 240V which means twice as much power as the RV outlet that is 30a/120v. If you look at the pictures, the ground pins are not the same and they are designed that way to prevent what you want to do because it is not safe. 

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aaaah, i figured I must have been missing something.  Thanks for clearing that up guys. 
Electricity would be so much easier if you could see it!

2 hours ago, Kirk Wood said:

That would be a good way to create an electrical disaster if they don't know what they are doing. 

Kirk, I know you're pretty electrically astute, but how would that be any different than plugging into the power pole at a campground?

 

 

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I'm with Kirk on this one. If I remember correctly the Dryer outlet had a ground but no neutral. That is a recipe  for disaster.  I know  the ground conductor and the neutral conductor are both at the same potential, but I think it is against code to use the ground as a neutral.

For those not experienced in electrical terminology the neutral is used to get 120 volt from a 240 volt circuit.

(hot{120 v}-Neutral-hot{120 v} volt) .

Ground is the connection to the metal frame of an appliance ( dryer )

Pat

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12 hours ago, jpatrickc said:

I'm with Kirk on this one. If I remember correctly the Dryer outlet had a ground but no neutral. That is a recipe  for disaster.  I know  the ground conductor and the neutral conductor are both at the same potential, but I think it is against code to use the ground as a neutral.

For those not experienced in electrical terminology the neutral is used to get 120 volt from a 240 volt circuit.

(hot{120 v}-Neutral-hot{120 v} volt) .

Ground is the connection to the metal frame of an appliance ( dryer )

Pat

I have always wondered why it is OK (within code) to NOT have the dryer with a third wire ground and then say it is a disaster to run that same setup to the RV, and have the ground and neutral tied together at the dryer outlet.  I do agree it is better, and probably safer if the 3 wire dryer outlet is not used.  However that doesn't change the fact that there are millions of dryers in this country which are operated w/o the third wire ground.

It is also good to note that new installations have 4 wire outlets for dryers, not the old 3 wire outlets.  I think that is why clothes dryers are sold w/o connectors.  You have to buy the connector which matches your outlet.

Keep in mind I am referring to wiring a plug to only bring 120V at 30amp to the RV, not to bring 240V to the RV.  That is done by buying a 30amp clothes dryer plug and wiring just one hot wire to the RV and tying the ground and neutral together at the dryer connection.   Technically you would not have a separate ground and neutral, back at the dryer outlet, but you would have the separate ground and neutral at the RV.  Just like the dryer doesn't have a separate ground and neutral when wired to the old 3 wire outlet.  Neutral and ground are tied together at the distribution box so in affect you are just extending the neutral and ground bond out to the dryer plug.

Again this is not code but it does work.

Edited by Al F

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12 minutes ago, Al F said:

However that doesn't change the fact that there are millions of dryers in this country which are operated w/o the third wire ground

While that is still true, the electrical codes have changed and no require a 4 wire supply with 4 pin plug. I don't know of anywhere you will find a new house today that has the old style of 3 pin dryer outlet. 

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2 minutes ago, Kirk Wood said:

While that is still true, the electrical codes have changed and no require a 4 wire supply with 4 pin plug. I don't know of anywhere you will find a new house today that has the old style of 3 pin dryer outlet. 

I figured that building codes now require 4 wire dryer outlets. 

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12 hours ago, jpatrickc said:

I'm with Kirk on this one. If I remember correctly the Dryer outlet had a ground but no neutral.

While that is true, it isn't the main problem with connecting an RV to it. The problem is that doing so applies twice the designed voltage to the RV's 120V circuits. Preventing people from doing this is the reason that the ground pin on the dryer plugs is shaped differently than that of the 120V, 30a plug. If you don't tinker with things you can't connect the RV to a 3 pin dryer plug or the 3 pin dryer cord into the 120V/30a power outlet for the RV. Look at the pictures that I posted. It was an attempt to keep people from making that mistake. 

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I'll be honest, the whole dryer convo went over my head. 

I did have one more question. I thought I remembered some of you saying the furnace would draw less power than an electric heater. My heater has a low and a high setting. The low setting draws around 6amps. I looked up online and it looked like a furnace draws around an average of 10 amps? Or am I looking at the wrong thing? 

Thank you again!

 

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6 hours ago, Sal said:

The low setting draws around 6amps. I looked up online and it looked like a furnace draws around an average of 10 amps? Or am I looking at the wrong thing? 

You are not looking at the wrong thing but you are comparing apples to oranges. The furnace will draw close to 10a of 12V power which is ( amps X volts = power) 120 watts. Your electric heater will draw only 6a but at 120V which is 720 watts if power. If your converter is drawing 120V shore power to supply the 12V/10a for the blower in the furnace, that means only about 1a from your 120v shore power since the converter is there to convert 120V-ac power into 12V-dc power like your batteries provide. 

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