30 amp or 50 amp

[zlamb0002]

I could possibly be running a 13" tv, a gaming system, mini fridge, 2 or 3 lights, and air conditioning at the same time. Which would fit my needs or does it matter?

One more question, how do I connect to a household plug, do I just buy an adapter?

[Johno]

20A would be fine for your listed cnfg. All of the RV electrical poles I have seen are either 30A with a separate 20A household outlet or 50A and 30A combo, but no 20A household outlet. If you cary a 30A to 15A/20A adapter (avilable everywhere for $5 to $10), you should be fine. However, do use a 10/3 extension cord to be sure it will cary the load sufficently. - John -

[starleen2]

We run about the same with a 30 amp plug - but have also ran the same with a 30 amp plug adapted to 20 amp to hook up to the house. bought the adapter at Wally world for about 5 bucks. A 30 amp plug is pretty much standard now at most RV parks and campgrounds, that why we choose a 30 amp plug

[wlooper89]

I also selected a 30A cable and power inlet on the teardrop. And I carry an adapter in case the campground only has 15-20A outlet. The things I may use could possibly add up to more than 20 amps, and if the campground has a 30A outlet I would not be limited to 20A. The 30A amp cord is heavier and has a different type of plug. I also carry a 50A adapter to my 30A cable in case the campground has 50A but not 30A outlets, but I have not encountered that situation yet. I would recommend a 30A circuit breaker in your teardrop electrical system if you ever plan to plug into 50A service with a 30A cable and adapter.

Bill

[Alphacarina]

The only RV's I'm aware of which come with a 50 amp plug are those which use two separate roof air systems - A 30 amp plug is way overkill for any teardrop

The reason for the 50 amp plug isn't so much for the extra amps - A 50 amp service contains 2 separate 120 volt lines so you can run half the RV (and presumably one of the air conditioners) on one leg and the other half on the other

Don

[wlooper89]

I am not 100 percent sure about this but believe the 50A service can also power 240 volt appliances if the RV is wired for it, using the two 120V wires. My adapter pigtail has a four pin plug on the 50A end and three on the 30A end. There is certainly no need for 50A in a teardrop. I just thought I might be at a campground that had 50A but not 30A service. So far I have not encountered that. But even if I did use a 50A outlet with the pigtail my circuit breaker in the tear would still limit me to 30A. I also carry a 20A adapter for the 30A cord in case only 20A outlet is available, but have not needed that yet either except at home.

I tend to agree that 20A would be plenty for a teardrop in most cases. For example my converter is rated at 25 amps D/C but draws 5.5 amps A/C. I was adding in things like a 1500 watt heater drawing 12 amps, a 1000 watt microwave about 8 amps, a coffee maker 8.5 amps. Granted these would probably not all be used at the same time.

So, while I decided on 30A service, I can certainly see the advantages of going with 20A. One advantage is being able to use some of the wiring items from Home Depot rather than ordering them or going to an RV store. The shore power cable, power inlet, A/C master switch and GFCI are all more expensive if rated for 30A. To find flexible 120V #10 wire I ended up ordering from a welding supply company. This photo shows my 30A cord with adapters for 20A and 50A outlets. The pigtail adapter uses just one of the two 120V pins on the 50A end.



I believe it is mostly a matter of how much one wants to use electrical things. For camping in a teardrop a lot of people would say less is better.

Bill

[TD4FREEW/CTD]

when you say 30a, are you talking about 120v or 240?

[Woody]

I would lean more towards the 30 amp service for shore power with a suitable 30 amp shore power cord. It has been my experience that most campsite shore power stations have had heavily worn 20 amp outlets and abused 20 amp breakers. The 30 amp outlets have less abuse overall than the 20 amp tent campers that plug in 50 amps worth of stuff on there sites that it damages the outlet and the circiut for others. I have seen the 20 amp outlets so worn out that the cord just falls out on it's own. I also reccomend a 90 degree adapter for plugging in (20 or 30amp) to lessen the pressure of the weight of the heavier cord from pulling out. Just because one can use 30 amp service to your main breaker on the panel doesn't that the rest of the wiring in your trailer has to be as heavy on individual breaker protected branch circuits for lights, microwaves,A/C etc. It would help if one knew the potential amp load required to power ones trailer during normal camping situations. I would include power hungray items like A/C, heaters, coffee makers, microwaves etc. I would recomend the 30 amp service to begin with

[brian_bp]

The only RV's I'm aware of which come with a 50 amp plug are those which use two separate roof air systems ...

... or are just wired to accomodate it (even though only one A/C is installed), like my fifth-wheel.

A 30 amp plug is way overkill for any teardrop

Sure, unless the tear is set up for all-electric cooking and heating. That's not common in RVs, but some travel trailers are done this way, and it needs a lot of power. For someone who always camps with power, it's an option.

The 50A service is certainly overkill for any reasonable (in my opinion) teardrop.

The reason for the 50 amp plug isn't so much for the extra amps - A 50 amp service contains 2 separate 120 volt lines so you can run half the RV (and presumably one of the air conditioners) on one leg and the other half on the other

Don

You can split the 120V stuff into as many circuits as you want, regardless of the input current capacity. 2 times 50A at 120V is a lot more power than 1 times 30A (again at 120V), and 30A can easily be not enough for even moderately sized travel trailers with a single A/C, if appliances such as microwave ovens are used. One good-sized A/C plus a common microwave can total over 30A with nothing else running.

Back in the teardrop realm, a little window A/C unit (or portable electric heater, at the other end of weather conditions) and other common 120V stuff should generally fit within 30A, and maybe 15 A, depending on the A/C unit and other details.

Never use A/C, or electric heaters, or cook electrically? Then I think 15 A should do fine.

[brian_bp]

I am not 100 percent sure about this but believe the 50A service can also power 240 volt appliances if the RV is wired for it, using the two 120V wires. My adapter pigtail has a four pin plug on the 50A end and three on the 30A end.

Yes, the 30A side has line, neutral, and ground pins; the 50 A side has two lines, neutral, and ground. In the 50A system 120V power is obtained between either line and neutral, and I assume that line-to-line should be 240V, just as in a similar residential circuit. I have not seen a 240V appliance in an RV, but perhaps someone has them.

[ninerhb]

I am not 100 percent sure about this but believe the 50A service can also power 240 volt appliances if the RV is wired for it, using the two 120V wires. My adapter pigtail has a four pin plug on the 50A end and three on the 30A end.

Yes, the 30A side as line, neutral, and ground pins; the 50 A side has two lines, neutral, and ground. In the 50A system 120V power is obtained between either line and neutral, and I assume that line-to-line should be 240V, just as in a similar residential circuit. I have not seen a 240V appliance in an RV, but perhaps someone has them.

This keeps getting repeated, but it's not quite correct. 50A and 30A just refer to the carrying capacity of the wires/plugs. Either size plug/wire can come in two configurations - 120V or 240V (30A does, I don't know about 50A). You can get twice the power using a 240V plug with only one more wire, because the two legs are out of phase and thus they can share a ground and neutral line. If RV plugs are using standard 240V twistlock (or heaven forbid, stove or dryer) outlets, then they're required to supply the proper out of phase power to the two 120v poles - if they're not, they're out of code. Of course, if you get two 120v standard outlets, there's no guarantee that they're in or out of phase, or even on different circuits.

A general sort order of power is:
50A/240 > 30A/240 > 50A/120 > 20A/240 > 30A/120 > 20A/120 > 15A/120

(There is one benefit of a 30A/120 over a 20A/240 - if you want to bring your welder along and need 25A, you can't get that from the higher-powered outlet.)

HenryB

[brian_bp]

I am not 100 percent sure about this but believe the 50A service can also power 240 volt appliances if the RV is wired for it, using the two 120V wires. My adapter pigtail has a four pin plug on the 50A end and three on the 30A end.

Yes, the 30A side as line, neutral, and ground pins; the 50 A side has two lines, neutral, and ground. In the 50A system 120V power is obtained between either line and neutral, and I assume that line-to-line should be 240V, just as in a similar residential circuit. I have not seen a 240V appliance in an RV, but perhaps someone has them.

This keeps getting repeated, but it's not quite correct. 50A and 30A just refer to the carrying capacity of the wires/plugs. Either size plug/wire can come in two configurations - 120V or 240V (30A does, I don't know about 50A). You can get twice the power using a 240V plug with only one more wire, because the two legs are out of phase and thus they can share a ground and neutral line. If RV plugs are using standard 240V twistlock (or heaven forbid, stove or dryer) outlets, then they're required to supply the proper out of phase power to the two 120v poles - if they're not, they're out of code. Of course, if you get two 120v standard outlets, there's no guarantee that they're in or out of phase, or even on different circuits.

A general sort order of power is:
50A/240 > 30A/240 > 50A/120 > 20A/240 > 30A/120 > 20A/120 > 15A/120

(There is one benefit of a 30A/120 over a 20A/240 - if you want to bring your welder along and need 25A, you can't get that from the higher-powered outlet.)

HenryB

I assumed that we were talking about common RV connections, especially since we were specifically discussing an RV 50A-to-30A adapter. Maybe I should have explicitly stated that.

Yes, there are 240V-only configurations with two hot lines and no neutral, 120/240V configs with two hot lines and a neutral, and 120V-only configs with one hot line and one neutral. Any of these could be 30A, 50A, or some other current rating. Any of those many combinations might be available in twist-lock and straight pin types. For instance, I had a 50A 240V (no neutral) socket in my garage for a welder... not something that would be used with an RV.

The "standard" configurations are defined by ANSI and NEMA in a standard called WD 6 - see NEMA connector at Wikipedia for an overview. You can buy a printed copy (for $144) or download it from NEMA free of charge.

In the RV world, the post at the campsite, and thus the cord that comes with the RV, typically comes in only two configurations over 20A, which are the two styles I listed:

NEMA 14-50 - 50A @ 120/240V (I have this on my fifth-wheel trailer)
NEMA TT-30 30A @ 120V (I have this on my 17-foot travel trailer)

Often, the RV's cord is detachable from the RV (such as on my fifth-wheel), and detachable 50A cords usually use a twist-lock connector at the inlet to the RV (presumably a NEMA L14-50)... but the other end of the cord is the normal non-twist NEMA 14-50. See a typical Marinco 50A cord and inlet for an example (mine are the same, but my cord is black).

By the way, and ordinary household socket is a NEMA 5-15R.

... and everywhere I put 120V really should be 125V (the rating of the devices), although the power supplied is typically somewhere between 110V and 120V.

[wlooper89]

I am not an electrician and not very familiar with house wiring, but believe that in the RV world the only way to get 240V is with a cable that has 4 wires: ground, common and two 120V legs. For RV the cords rated for 30A or less have only three wires.

This is just an observation and 240V is not something I want or need. My only connection with this subject is having bought a 50A adapter for my 30A shore power cord in case the campground does not have 30A outlets. The adapter has four pins on the 50A end but uses just one leg of the 50A 120V wires to connect to my three-wire 30A inlet.

Bill

[BPFox]

Here's a pretty good web site that explains in pretty good detail RV electrical configurations. This includes both the 50 amp and 30 amp connections we are discussing here.

http://www.myrv.us/electric/


The RV set up should not be confused with typical residential wiring as they are not the same. For example if you have an old 30 amp 240 volt plug that only had three prongs (the old ones didn't have a ground) and you think you can plug your RV into it, you are not going to be happy with the results. The good news is, your RV plug won't plug into a 30 amp 240 volt dryer plug. There is a good reason these plugs won't go together even though they look similar. Folks get into trouble when they try and use stuff they have laying around. This attempt to save some money could really cost you in the long run.

[wlooper89]

Hello BPFox, that is a very good web site for RV wiring. It appears my power cord may be a little under sized for 30 amps and 40 feet lenght with #10 wires. Maybe just barely enough. That was very informative.

Bill