Why 30a (120v) at Home?

Bill.Satellite wrote:
Yes, 240V is available and you are right, never was not the right word. However, despite 240V being available, the plug is still wired to make 2 separate 120V circuits (the plug now....). You have to do special wiring from the breaker box to the appliance to make use of anything other than 120V.

OK. This phraseology I agree with. :B I know it is knitpicky, but imprecision in electrical work with people who don't really know what they are doing can be dangerous. My objection was that your previous phraseology made it sound like the 50a outlet was 120v, and I don't want the average homeowner who thinks "Duh, I can do that" to misunderstand.

Yes, 240V is available and you are right, never was not the right word. However, despite 240V being available, the plug is still wired to make 2 separate 120V circuits (the plug now....). You have to do special wiring from the breaker box to the appliance to make use of anything other than 120V.

Bill.Satellite wrote:

Bobbo wrote:

Bill.Satellite wrote:
If for no other reason, the 30 amp plug is a much more reliable connection than a standard wall plug. 15a, 30a, 50a is all 120V, just a matter of wiring and the cost difference between running a new 15a line or a new 30a line is minimal.

Careful here. The 50a outlet is a 240v outlet. Most RVs just use the legs separately giving them 120v on each leg. But to label it as a 120v outlet is misleading. The 50a outlet is wired EXACTLY like your 4 pin 240v dryer outlet and uses a ganged 240v breaker.

No, I don't need to be careful. The installer might want to be careful that they wire the plug properly. There is NEVER a 240V circuit available on a properly wired 50 amp RV plug.

"NEVER" is a big word. The people with a 240v dryer in their RV might beg to differ. And, yes, some folks do have a 240v dryer in their RV. But, if you take your multimeter between the two hot legs of a 50 amp outlet, I think you will find 240v, even if most RVs don't use it that way.

Learjet wrote:

BFL13 wrote:
Curious what the extra 15a is for.

We only ever need 15a at home where we park the rig and leave it on shore power all the time. 15a does battery charging and any fridge time on 120v. What else is there to run at home?

Must be some reason to do 30a, because people set up for that, but I can't figure out why. Maybe I am missing a trick?

Thanks

I'm sorry...but I didn't think and still don't think this is serious question for a member who has RV experience. :h

Nope. I just completely forgot about air conditioning. (We don't need that where we RV--been years since we ever even fired it up, when on the Mainland back when.)

It is true that we can't run the battery charger full blast and leave the fridge on 120v, but that is easily got around the few times it would count.

Once the amps taper somewhat, there is "room" for the RV fridge. However the only time the batts would be recharged at home is on return, and we are emptying the fridge to put stuff back in the house fridge, so it is just not a real "issue". Just wait till the fridge is empty, then do the battery recharge.

Yes, the house things are also on the circuit so you can pop a house CB if you try to do too much at once. Just not a problem for us, but it certainly would be elsewhere, as these replies have shown.

Using 12 wire for the extension from a 15a house/garage receptacle does help with voltage sag if say you ran the RV microwave when using it as a cottage.

However, I "get" the idea of having a real 30a RV pedestal in your yard to cover all bases, now that it has been explained so well here :)

Years ago, Monaco Hi Line units had an optional 220 dryer instead of the usual 120 Dryer and 120 Washer. The Dryer plug was special wired from the main breaker panel for the required 220 volts those dryers use. But. This is the only instance I have seen on sub million dollar motorhomes that had a 220 outlet in the RV from the factory. Doug

myredracer wrote:

What I don't understand is why the heck the NEC requires every single pedestal in an RV park to have a 15/20 amp recept. in addition to a 30 amp and/or 50 amp one. Has been like that for decades. Maybe a holdover from 5+ decades ago or for maintenance staff?

My guess is because it is the only GFCI protected source of power at the site, so people will be less likely to carry an adapter and plug their extension cord into the 30 or 50A service via the adapter leading to outdoor electrical use without GFCI protection.

BFL13 wrote:
Curious what the extra 15a is for.

We only ever need 15a at home where we park the rig and leave it on shore power all the time. 15a does battery charging and any fridge time on 120v. What else is there to run at home?

Must be some reason to do 30a, because people set up for that, but I can't figure out why. Maybe I am missing a trick?

Thanks

I'm sorry...but I didn't think and still don't think this is serious question for a member who has RV experience. :h

Lots of interesting replies about how people use their RVs etc.

No idea about codes, but our 2003 Komfort 5er (made in Oregon at the time) has two different wiring diagrams for the 7300 power centre 120v breakers in its manual.

The "US" version has all "20a" breakers, while the "Canadian" version has "15a" instead. Except for one 20a. The 15 receptacles are all straight 15 not 15/20s. The Canadian one also has the water heater and microwave sharing a 15 so you have to use one or the other. The US version has them separate.

The Canadian version 15a circuits have 14 wire and the 20a has 12 wire. I have not seen a US version to know if it has 12 wire on 15/20s for its "20s" or what. It should. I very much doubt it would use straight 20s for its receptacles.

OTOH I have seen folks here use "20a" in an arm-wavy sort of way when they mean 15 or perhaps 15/20, so you have to interpret.

After I had two cheap extension cords go up in smoke in our driveway after we got our 1st TT, I ended up installing a dedicated 30 amp recept. where we park the trailer. If plugging into a recept. at home, you should be turning off the power first because the converter has an inrush current that causes pitting on the contact surfaces, attracts dirt and leads to overheating. I installed a disconnect switch adjacent to the 30 amp recept. No more melted extension cord connectors and no adapter needed.

If installing a new dedicated recept. for an RV, I recommend installing a disconnect switch near it. I used a motor-rated disconnect switch. I doubt it would be legal to install a 30 amp recept. on 15 or 20 amp wire even if labelled with a max. draw. You may not normally need 30 amps, but sometimes the heavier ga. wire can help. We have a built-in vacuum that draws high current and an ordinary extension cord would result in high voltage drop.

If you have no choice but to use an extension cord, I'd get one that is UL/CSA listed (not all are) and use a min. #12 ga. commercial grade one with better plug & connector. A "heavy duty" label means nothing.

What I don't understand is why the heck the NEC requires every single pedestal in an RV park to have a 15/20 amp recept. in addition to a 30 amp and/or 50 amp one. Has been like that for decades. Maybe a holdover from 5+ decades ago or for maintenance staff? I almost never see them being used except in tent only areas or when an RV-er is trying to get more power into a 30 amp RV. The NEC only requires a min. #10 wire to 30 amp pedestals and does not require simultaneous demand in load calcs. In some cases, especially in older CGs, can result in excessive voltage drop.

Our Canadian Electrical Code doesn't have code requirements for RV parks or RVs like the US does.

wolfe10 wrote:
We could be getting into semantics here. I know Bill is very familiar with 120/240 VAC wiring.

He is correct that very, very few RV's use both hots to power a single appliance. Said another way, the appliances are wired to use 120 VAC= one hot, one neutral and ground.

BUT, a proper 50 amp RV outlet does have TWO hots. Between L1 and L2 (the two outer straights) DOES READ 240 VAC.

Good clarification. I only recall one poster with a 240V appliance and it was a WD.

But on another note: My rig and my 04 rig have a EMS that detects 240V or not to set load shedding to 50A or 30A. So if you like that is a 240V appliance and the associated equipment is rather common.