Stupid question about power

I should add here, there are two types of breakers:

Magnetic:
Will trip almost immediately at the rated current.

Thermal:
Will carry the rated current for one minute, then trip.

Further:
It is standard practice to de-rate a circuit to allow for the inrushes caused by motor start-ups and incandescent lamp turn-ons.

One CG that we stayed at used a 100KVA transformer to feed 18 sites. That’s 100,000/(18*240) = 23A per site (or 46A at 120V). Given normal distribution of power to the sites it's very unlikely that the main transformer CB would every be tripped due to overloading.

It that case the label doesn't make much sense. I doubt that there is any CG that can supply 100% of the power to every site. Houses are basically the same. The CB panel rating is less that the total of the breakers.

However 40A is a lot of power (9,600W) for a RV to use. But if someone actually used 50A they would be fine as some other sites would be using less.

The 30 Amp GFCI is code in Illinois.

The 40 Amp "limit" is because the transformer (and main breaker) feeding 25 campsites is rated for only 1000 Amps (240,000 VA).

There is 240/120 Volts at the 50 Amp outlet.

CA Traveler wrote:
Interesting picture. 30A GFIs aren't very common. And what does 40A limit mean? 40A for the 50A plug? 40A for both the 20A and 30A plugs?

Wonder if there is 240/120V to the plugs or if it's just a upgraded 30A circuit for the 3 plugs.

That label would be a big red flag for me.

camperpaul wrote:

wa8yxm
Good post.

Interesting picture. 30A GFIs aren't very common. And what does 40A limit mean? 40A for the 50A plug? 40A for both the 20A and 30A plugs?

Wonder if there is 240/120V to the plugs or if it's just a upgraded 30A circuit for the 3 plugs.

That label would be a big red flag for me.

camperpaul wrote:

I think the warning comes from the fact that far too many members of these forums have plugged a 30 amp rig into a dryer, air compressor or welder outlet that was 240 volt... I mean some of those outlets look just like a TT-30, the TT-30 plug fits them just fine,,, but alas 240 volts lets all the magic smoke out of your expensive electronics and without that magic smoke.... they do not work.

mena661 wrote:

Dutch_12078 wrote:

Fishinghat wrote:

Don't worry. You won't find a campground with 220 volt service or 50 cycle here in the US, but those are typical in foreign countries.

If you really believe that no campground in the US has 220 volt service available, go to any properly wired 50 amp outlet and connect your volt meter to the vertical slots on each side. Make sure you have it set for at least 250 volts...

X2, "50 amp" service is 240V @ 100 amps.

Technically you're right. A 50 amp outlet has the potential for 240 volts and some high end coaches take advantage of that potential. But those coaches are very uncommon. However, in Europe 240 volt systems are the norm, and I think that's where the warning originated. My concern was that the poster understand there is little to worry about here in the US. The way most rigs are wired, they will use only the 120 volt power and won't have a problem even if plugged into a 50 amp outlet, even though that outlet does have the 240 volt potential. The object here is not to confuse a newbee or others about damaging their rigs if they plug into a campground post using an adapter purchased from an RV store or even an home improvement store. They are going to be OK.

Someone up-thread posted a photo of a standard triple park outlet box.

Parks will, depending on the prak have either boxes like that, Boxes with only the two right hand outlets or boxes with just one of the two right hand outlets.

The one on the left (has 3 flat slots and one round or "D" or "U" shaped slot) is 50 amps at 120/240 volts This is for a 50 amp rig.. More on that in a bit.

The other two are 120 volt (30 and 15/20 amp respectively.. I suspect your rig is one of those.

Plug into the outlet that matches your plug.. That simple.

I do recommend measuring voltage BEFORE you plug in (Some parks .. weird things happen)

If you have a 30 amp rig and get in a park with only 50 amp outlets.. Get a dogbone adapter (This has a 50 amp plug and a 30 amp outlet with a short cord between them) it handles everything, again MEASURE before pluging in rv though.

The major danger with 30 amp rigs is "other than RV park" 30 amp outlets. Example you hire Joe the electrician, tell him it's for your RV, he puts in the TT-30 outlet (Which is clearly marked 125 volt max) and wires it for 240 volts cause HE sees a dryer or air compressor or welder outlet, not an RV outlet like you told him.

Or pluggin in at a friend's or a shop or somewhere else wher eit's a 240 volt outlet.

If you have JOE (Generic name) install an outlet for you.. Get a 50 amp. Safer that way, less chance of a screw up.

^^^ 240v 50a, not 100a

Some call it 120v 100a but really two x50a at 120v. Can't actually run a 60 amp item.