Pulling more than 50 amps ?

cavie wrote:

fcooper wrote:
100 amps available....50 amps per leg x 2 legs...so answer is yes

100 amps available never came out of the mouth of a true electrician.

It would require a very precise balanced load. If one leg goes over 50 amps the breaker will trip. Period.

True. However, if L1 is providing 50 amps to its appliances, and L2 is providing 50 amps to its appliances, add up how many amps the appliances are using.

The 100 amps figure is an analogy to get the idea across to someone who knows nothing about electricity. No one ever claimed that it was a technical description of exactly what is going on.

As a Pharmacist, people ask me how aspirin prevents heart attacks. I tell them that some heart attacks are caused by platelets sticking together forming a clot that obstructs blood flow in the small vessels of the heart. (That is what platelets do, to clot off after a cut.) Without blood flow, the tissue dies. The aspirin greases the platelets so they can't stick together nearly as easily. That is an analogy. Aspirin does not cause grease to coat the platelets, but the patient gets the idea that the platelets don't clump up and block blood flow.

The 100 amp statement is an analogy that Joe Blow can grasp.

time2roll wrote:
Three? Each is maybe 16 max so even 4 would pull only 32 per side max.
Licensed electrician or handy man?

He is referring to total load of an RV with 3 A/C's. Not the load of 3 A/C's;)

fcooper wrote:
100 amps available....50 amps per leg x 2 legs...so answer is yes

100 amps available never came out of the mouth of a true electrician.

It would require a very precise balanced load. If one leg goes over 50 amps the breaker will trip. Period.

TechWriter wrote:
Our park electrician says that some of the big rigs with 3 ACs and electric everything can sometimes draw more than 50A from a 50A pedestal.

Truth or BS?

There are several possible responses to this.
1: Political and thus no further mention
2: YES. for a tiny fraction of a second as the A/C starts But then so do smaller units.. (The starting surge can push it over 50 amps but if it stays there for long TRIP goes the breaker)
3: YES. sort of but not really 50 amps is 50 amps at 240 volt divided. (Kitchen term)( meaning two legs of 50 amps. NOW some people think of this as "100 amps" but it's not it's 50 amps.. I do not want to get into the reason I say this before breakfast but basically if perfectly balanced every amp is used twice (The neutral wire carries the DIFFERENCE between L-1 and L-2) so no more than 50 amp flows in any wire. If you draw more than 50. CLICK goes the breaker.

4: If you draw more than 50 CLICK goes the breaker so the Park Electrician was LYING to you and that is the best and final answer.

I had that happen in one RV park the manager claimed to be an electrician and told me the problem and the reason the breaker on my site needed replacement was because of those big rigs pulling more than 30 amps.... it was the 50 amp breakers that failed.

I out rank him on electrical/electronics stuff (Certified electronics technician, even if I don't work in that field anymore)

I can easily exceed 50 amps 240 VAC with 3 A/C units, AquaHot with a 2000 watt element on each leg, microwave, fry pan, hair dryer, 240 VAC dryer, instahot, etc. I have to watch it closely when DW gets busy.

Assuming he meant 50amps @ 120v...sure.

And since it's very rare for an RV to have 240v devices, the assumption of 120v is reasonable and yes, the big units can certainly be pulling more than 50 amps:
- 3 Air/con at 15amp each is 45amp
- Fridge maybe another 4-5 amp
- Water heater another 10 amp
- Battery charger another 10amp
- TV another 1 amp
- Microwave 7-10amp
- Ceiling fan another 4 amp
- RV Dryer 15amp(?)

If you have all these going simultaneously, that's somewhere around 100amps @ 120v...in reality, he probably has a load shedding device kicking in at this point as he bumps up against the peak draw.

Electrical must always be designed for worst case.

Aside from water heater, reefer and battery recharging it is quite possible for a park power blip to knock all A/C off line. Then all of them may attempt a high head re-start. If the park is nearly full, the park becomes an involuntary appliance durability tester.

Add up all the possible loads. Neither leg will exceed 50 amps I suspect--but there are 2 legs.

In winter I can draw more than 50 amps--but it is shared over both legs.

Park electrician is correct.

Stating an amperage without specifying the voltage is really only describing part of the story. More than 50A @ 120V? Sure. More than 50A @ 240V? Sure... for a few seconds until the breaker pops.

Honestly, RV power is listed in kind of a messed up way and it rarely gets clarified. A 30A hookup is 120V. A 50A hookup is 240V. So, if you just want a linear scale for comparison sake, a 30A hookup is 30, a 50A hookup is 100.