Forum Discussion
46 Replies
- Hank_MIExplorer
happycamper002 wrote:
What Old-Biscuit is saying, is:
Even though the pedestal provides 240 volt at the 50 Amp plug, the two (240 volt) legs are not used (simultaneously) for appliances that are made for 240 volt operation (unless you are driving a huge Prevost) to run an electric range, electric dryer or huge 4 ton A/C.
As soon as the 50A power enters the RV, it is split into two branches that power two separate buses in the load center.
This is made to balance the load between the two legs when the system is loaded to full capacity.
Utility providers requires this to protect their equipment.
Which is exactly what occurs in the service panel in your house. One hot leg feeding one buss and the other hot leg feeding the other buss. If you had a gas clothes dryer and gas stove and perhaps no central AC would your house then be considered a 120v house? No it's still 240v. - Hank_MIExplorer
myredracer wrote:
There are some non-electrical professionals here making incorrect statements.
The pedestals have both 120 and 240 volts available but almost all RVs are designed to operate everything at 120 volts. FWIW it's 120 & 240 not 110 or 220 and you always want to be operating at as close to 120 volts as possible.
And the reason that 50 amp RVs normally do not have 240 volt appliances is to allow the shore power cord to be plugged into a 30 amp, 120 volt pedestal. The NEC currently only requires 20 percent of an "RV park" to have 50 amp pedestals. As of 2005, only 5 percent of an RV park was required to have 50 amp pedestals. Finding a 50 amp pedestal in a CG can be very hard in the high season. Some CGs may have exceeded code requirements, but the majority have built to min. code requirements. Old RV parks may even have NO 50 amp pedestals.
If you plug a 50 amp RV into a 30 amp pedestal using an adapter, the RV's panel and shore power cord will have both hot sides of the 120/240 volt circuit connected together inside the adapter as shown in the 1st diagram below. Although you end up having 50 amps at 120 volts available up to the point of the pedestal, the 30 amp breaker in the pedestal limits you to 30 amps. No technical reason why you couldn't use 240 volt appliances but if plugged into a 30 amp pedestal they sure wouldn't work very well at 120 volts...
IMO it's very wrong for RV manufacturers to be selling 50 amp RVs to people when they don't tell buyers idea how hard it is to find a 50 amp pedestal in a CG.Hank MI wrote:
On this comment, this is incorrect. The current on the hots in a 120/240 volt cancel out on the neutral. For ex., if one leg was drawing 40 amps and the other 20 amps, the current on the neutral would be 20 amps. If both hot legs were carrying the same 40 amps, the neutral would have zero amps flowing in it. A neutral is there to handle the highest imbalanced current in a 120/240 volt circuit and the neutral wire is normally sized to match that of the hot legs. In some cases, code allows a reduced neutral size like on a service into a building.
All I can say is WOW!
No neutral canceling can occur at your breaker panel. That means the neutral line must be capable of carrying 100 amps and need to be twice as large as the hot legs.
Circuits that are 120/240 volts are not normally referred to as having phases although the current is flowing 180 degrees apart. A 120/240 circuit is 240 volts with a center tap grounded at exactly 1/2 way as in the 2nd diagram and the current in each 240 volt leg flows in the opposite direction and alternates one way to the other at 60 times/second.
There are a few RV parks (CGs) out there that have been wired at 120/208 volts which is more often seen in industrial and commercial facilities. If did in fact have anything in your RV that is designed to operate at 240 volts (dryer for ex.) it would only produce 75 percent of it's rating but anything rated at 120 volts would be unaffected.
You misunderstood what I was saying. I said if both hot legs were in phase, meaning supplied from the same source hot leg then no neutral canceling would take place. If the 2 hot legs are 180* out of phase then neutral canceling would take place. People keep insisting the 50 amp supply is 2 120v supplies. Technically and by code it's a 240v supply as the 2 hot legs are 180* out of phase. As i said earlier it's no different than the service coming into your house. Almost everything in your house runs off 120v, one of the 2 hot legs. It's quite possible to have no 240v loads at home.
Why people keep insisting that the RV 50 amp supply is some how different is beyond me. It's a 240v 50 amp supply. How the 2 hot legs are used to supply 120v or possibly together to supply 240v is irrelevant. Same thing occurs in your home but it's still a 240v supply. - rhagfoExplorer III
allen8106 wrote:
All 50 amp feeds are two legs of 110 volts. All campers are 110 volts. No such thing as a 240 volt camper.
Not true soon to install Cheap Hat and use 240 v 30 amps for heat. The reason you only have 110 volts is the design of the breaker box. The only spot you have 240 volts is at the main. theoldwizard1 wrote:
That would be a 5-15 as the '6' would designate 240 volts without a neutral.
I bought him 2 adapters: TT-30 female to 6-15 male....- myredracerExplorer IIThere are some non-electrical professionals here making incorrect statements.
The pedestals have both 120 and 240 volts available but almost all RVs are designed to operate everything at 120 volts. FWIW it's 120 & 240 not 110 or 220 and you always want to be operating at as close to 120 volts as possible.
And the reason that 50 amp RVs normally do not have 240 volt appliances is to allow the shore power cord to be plugged into a 30 amp, 120 volt pedestal. The NEC currently only requires 20 percent of an "RV park" to have 50 amp pedestals. As of 2005, only 5 percent of an RV park was required to have 50 amp pedestals. Finding a 50 amp pedestal in a CG can be very hard in the high season. Some CGs may have exceeded code requirements, but the majority have built to min. code requirements. Old RV parks may even have NO 50 amp pedestals.
If you plug a 50 amp RV into a 30 amp pedestal using an adapter, the RV's panel and shore power cord will have both hot sides of the 120/240 volt circuit connected together inside the adapter as shown in the 1st diagram below. Although you end up having 50 amps at 120 volts available up to the point of the pedestal, the 30 amp breaker in the pedestal limits you to 30 amps. No technical reason why you couldn't use 240 volt appliances but if plugged into a 30 amp pedestal they sure wouldn't work very well at 120 volts...
IMO it's very wrong for RV manufacturers to be selling 50 amp RVs to people when they don't tell buyers idea how hard it is to find a 50 amp pedestal in a CG.Hank MI wrote:
On this comment, this is incorrect. The current on the hots in a 120/240 volt cancel out on the neutral. For ex., if one leg was drawing 40 amps and the other 20 amps, the current on the neutral would be 20 amps. If both hot legs were carrying the same 40 amps, the neutral would have zero amps flowing in it. A neutral is there to handle the highest imbalanced current in a 120/240 volt circuit and the neutral wire is normally sized to match that of the hot legs. In some cases, code allows a reduced neutral size like on a service into a building.
All I can say is WOW!
No neutral canceling can occur at your breaker panel. That means the neutral line must be capable of carrying 100 amps and need to be twice as large as the hot legs.
Circuits that are 120/240 volts are not normally referred to as having phases although the current is flowing 180 degrees apart. A 120/240 circuit is 240 volts with a center tap grounded at exactly 1/2 way as in the 2nd diagram and the current in each 240 volt leg flows in the opposite direction and alternates one way to the other at 60 times/second.
There are a few RV parks (CGs) out there that have been wired at 120/208 volts which is more often seen in industrial and commercial facilities. If did in fact have anything in your RV that is designed to operate at 240 volts (dryer for ex.) it would only produce 75 percent of it's rating but anything rated at 120 volts would be unaffected. - happycamper002ExplorerWhat Old-Biscuit is saying, is:
Even though the pedestal provides 240 volt at the 50 Amp plug, the two (240 volt) legs are not used (simultaneously) for appliances that are made for 240 volt operation (unless you are driving a huge Prevost) to run an electric range, electric dryer or huge 4 ton A/C.
As soon as the 50A power enters the RV, it is split into two branches that power two separate buses in the load center.
This is made to balance the load between the two legs when the system is loaded to full capacity.
Utility providers requires this to protect their equipment. - accsysExplorerMany of the newer large luxury MHs have the capability of using two 50 amp outlets which some of the higher end RV resort sites can furnish. Some have four air conditioners, 240V heating, 240V range top, etc. and need the 240V/100 amps to "survive"!
- theoldwizard1Explorer II
garyemunson wrote:
Well, as someone who is electrically literate, ...
That is my son-in-law, a new TT owner !
I bought him 2 adapters: TT-30 female to 6-15 male and TT-30 female to 14-50 male. I told him to use which ever one fits the cord from his trailer and the holes in the outlet on the pedestal.
He does have a Progressive Industries EMS-PT30C. - 2oldmanExplorer II
luberhill wrote:
Depends on what the socket looks like.
I see the heavy cords and plugs for the class C's so is power at campgrounds 110 or 220? - RoyBExplorer II
allen8106 wrote:
All 50 amp feeds are two legs of 110 volts. All campers are 110 volts. No such thing as a 240 volt camper.
I think you will find some of the very high-end $$$ RV Traveler Motorhomes that have built-in Washer and Dryer combos will be equipped with 240VAC circuits to operate the dryer just like in the house.
This is special wired to tap into the 240VAC HOT1 and HOT2 wire sources to do this.
almost all of the other 50AMP SERVICE RV UNITS used for RV Travelers and RV Camping only will have two legs of 50AMP 120VAC service being used from the 50AMP RV Service connection.
Roy Ken
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