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Topic: What is 100 Amp Service?

Posted By: SCVJeff on 12/09/09 10:49pm

rolnhome wrote:

SCVJeff wrote:

The service could just as easily be 120V single phase/100A and 99.9% of the coaches wouldn't know the difference. This is exactly the same as using a 30A dogbone sans the current.

My coach would reconize a 120v service. But it also assumes a 30 amp 240v is a 50 amp 240v because of the EMS and the way it reads incomming power. The EMS only knows between 30amp 120v and 50 amp 240v and only reads used amperage from 120v. To pull 100 amps total the coach needs the 240v power; otherwise it assumes 30 amp 120 and pulling more than 30 amps at 120v it starts shuting down. I believe most coaches these days are set up this way.
Kind of.. Because the EMS sees "in-phase" power it assumes that it's on a 20A or 30A (user specified in my case) service and starts throttling back the appliances. It has no other way to even guess at the rating of the service on the pedistal. But that doesn't mean that the coach won't run on single phase 120V service. It has no idea that you just fed it from one side of your residential 240V/ 100A service.

My SurgeGuard will read current from both incoming legs, and I need to add them up to decide what my true draw on the single phase service really is, but will assume it's nothing exceeding [email protected] 1P

Jeff - WA6EQU
'06 Itasca Meridian 34H, CAT C7/350

Posted By: time2roll on 12/09/09 11:00pm

westernrvparkowner wrote:

-Gramps- wrote:

djevans wrote:

I don't think there's a specific "plug type" - I'd say, although not absolutely sure, they're simply referring to peds like this that are 100 amp capable

They may indeed though, be capable of 100 amp total power

Exactly. I have 100 amp service to the rv lot I own at Deer Creek Motorcoach Resort in Galax Va. The ped looks just like the one in the picture.
Unfortunately, what the "100 amp" reference on this pedestal is referring to is the rating of the meter that is supplied, not the actual rating of the pedestal. A one hundred amp meter means that the meter is capable of supply 100 amps of service thru each 120 volt leg. If the pedestal is properly wired, one leg of the service will serve 1/2 of the 50 amp plug and the 30 amp plug while the other leg will serve the other half of the 50 amp plug and the 20 amp plug. This will help balance the load.

By the description it says other connector configuarations are available. I assume you could have them supply two 50 amp connectors for RV 100 amp service.

2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675w Solar pictures back up

Posted By: Tinstar on 12/09/09 11:59pm

Uh, I forgot the question.

">Never pass up a chance to go somewhere">

Posted By: randco on 12/10/09 03:31am

Badeye wrote:

Not to sound sarcastic, but please be careful in offering advice and comments about something as dangerous as the electrical systems in our coaches unless you know absolutely for sure that you know what you are saying is factual. We do not want to get someone injured or killed. I personally have not seen any of the new 100 and 200 amp services being offered by some of the upscale parks so I will not offer a comment. I am sure that the new all electric coaches with house type appliances require more than what we know as "50 amp" service. It is interesting though that the Onan 7500 Quiet Diesel generator that many of us have in our motorhomes has two circuit breakers, one 30 amp and one 20 amp and they are both the same phase of 120 volt AC. This is a single phase generator.


The Onan 7500 generator has the potential to produce 7.5 kW. One kW or kilowatt = 1,000 watts. So the Onan 7500 has the potential to produce 7,500 watts maximum which is 62.5 Amps at 120 volts. Your Onan 7.5 kW generator has breakers for a total of 50 amps which is about 80% of the generators potential capacity.

Posted By: randco on 12/10/09 04:25am

Acampingwewillgo wrote:

Im sorry but a 50 amp RV outlet does indeed provide 100 amps...I dont care where your degree came from. In a typical house you have many three wire circuits....meaning you have a 3 wire romex supplying two separate 20 amp circuits sharing the neutral wire, in this configeration, you are getting 20 amps on each circuit. This is precisely what you get on a 3 wire RV outlet(the ground wire being the forth wire) two separate hot leads sharing a like sized neutral wire. Would you not agree that if you took two separate single pull 30 amp 110 volt breakers, a single hot wire to each and a like sized single neutral(plus ground) you would in fact have 60 amps of 110 volt power. Just because you are using a 50 amp two pull breaker doesnt change the fact that the two hot leads are on separate legs of the panel. Of course this is all IMHO! I certainly know I pull more than 50 amps when I have the airs running, the battery charger on, the microwave on, the water heater on, the fridge on, the freezer on...well you get the picture.

On edit....a typical power cord for an RV is #6 x4 because it is a portable cord set.

"Im sorry but a 50 amp RV outlet does indeed provide 100 amps"

If the outlet is breakered with a dual pole 50 amp breaker the maximum amperage draw would be 50 amps. 6,000 watts per leg at 120 volts or 12,000 watts or 240 volts.

"In a typical house you have many three wire circuits....meaning you have a 3 wire romex supplying two separate 20 amp circuits sharing the neutral wire, in this configeration, you are getting 20 amps on each circuit."

Yes, and if each was loaded to it's potential you could have a 40 amp load at the main breaker panel. However, that doesn't mean that you could have 30 amps on one circuit and 10 on the other. You can only have a maximum of 20 amps per circuit. If you have fifteen 20 Amp circuits on a 120/240 volt 200 Amp electrical panel do you have 300 amps? No, the maximum you can have is 20 amps per circuit and the total circuitry can not exceed a total 200 amps.

Posted By: Bumpyroad on 12/10/09 04:39am

westernrvparkowner wrote:

Sorry to disappoint all you experts, but I have seen the beast and it has two 50 amp cords. It was a 2008 Newell, all electic, and I do mean all electric. Things like 4 ac units, 240 volt clothes dryer, 240 volt aqua hot, 240 volt full size convection oven and who knows what else. I have no idea how the energy management system worked, but I assume there are two separate panel inside the coach, each supplied by a 50 service cord. The guy plugged each cord into a standard 50 amp pedestal and was happy as a clam. He carried a 50 foot 50 amp extension cord and told me he just rented two 50 amp sites side by side if the park couldn't accomodate two connections at one site. He did show me the battery bank of 12 6 volt gel mat batteries and he told me he could run the entire coach off the inverters for several hours if necessary. I don't care how you actually count the amperage, but in common usage, two 50 amp plugs equals 100 amp service to me.

OK as far as I am concerned, this is the "winner". 100 amp RV service appears to be dual 50 amp service (which is really dual 100 amp service).

Posted By: randco on 12/10/09 05:19am

I sort of agree with you Bumpy. But without knowing what the campground is actually advertising it's difficult to say. Yes it could be a power pedestal with two 50 amp receptacles or it could be a pedestal that has the proper wire size run to it for the possibility of a vehicle or park model that has a main breaker in excess of the standard 50 amp and less than or equal to 100 amp.

Posted By: Bumpyroad on 12/10/09 06:11am

If dual 50 service is standard for these "monsters" I would think that a RV park would wire to suit them, instead of park models which would be more likely in a mobile home park.

Posted By: randco on 12/10/09 07:20am

Yahooligan wrote:

NitroShark wrote:

pretty simple.

It's called Ohm's law.

The mathematical equation that describes this relationship is ..

amps= Volts/Ohms


Ohm's law is for determining current based on voltage and resistance as you say, but that doesn't apply here. We are not talking about pulling 100A of 110v power to supply a single load that would only take 50A at 240v. Folks are claiming, incorrectly, that you can get 100A of 120v power out of a 50A 240v outlet when in fact you can get two 120v 50A sources out of a 240v 50A outlet.

Tell me what would happen if you fed two 120v 50A legs into a single wire. Anyone? Anyone know what would happen[emoticon]

If the 120/240 V 50 amp service is wired correctly, snap crackle and pop and one or both circuit breakers would have tripped.

If it's a "fake" 50 Amp service, connecting the 50 amp legs into a single wire will do nothing. The voltage will be ~120 when tested to Neutral or Ground.

Posted By: randco on 12/10/09 07:37am

ChaosAgent wrote:

Just to jump back in here...

If, as some here say, I can't pull 50 amps from each side of 50 amp service, for a total of 100 amps, then why does my breaker on the pedestal consist of two 50 amp breakers linked together, and also, to repeat what I posted a little earlier, why does my EMS at times, show me pulling as much as 70 amps total on both lines coming in?

The 50 amp service is really known as 120/240 Volt - 50 Amp split phase. The breakers are tied together to provide a maximum of 12,000 watts at ~240 Volts. If either leg of the service exceeds 50 amps it will trip both breakers because 50 amps at ~120 Volts or 6,000 watts is the maximum load the individual breaker can handle.

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