50 amp service conversion question

[JRBME]

Originally Posted by sdowney717

Think of it as power in wattage, 50 amps is what the panel is limited to for each leg, you dont get 100 amps out of the distribution panel on any one circuit, the max for a 50 amp panel is a 50 amp breaker.

watts = volts times amps. total power watts stays the same, if you join two legs together to double the volts, the amps do not also double. it will still be breaker limited to 50 amps. But you could draw 50 amps off on leg and 50 amps off the other leg, but you cant combine two legs to draw 100 amps at double the volts as in a 240 vac circuit to feed a single 100 amp 240 vac load. This means you can use 6 gauge wire to supply a 50 amp panel having two 50 amp supply legs, with one neutral. One neutral works if each 50 amp leg is on a different phase, as the neutral even though returning 50 amps from each hot leg, never exceeds 50 amps flowing on the neutral. The phasing is a sine wave, so as one leg drops the other builds up and the net is the same current flow.

50A service is typically two totally separated 120vac circuits. It isn't 'one' 50 A circuit. It would resemble a 240vac setup, but the two circuits(legs) don't commingle so you have two separate systems with no 240vac pitential. Usually front air conditioner on one leg and rear on the other.
Unless you rewire the RV in order to take advantage of the two 120v circuits, it won't help much.
You cannot combine the two 50A circuits....that would be 240 and uncommon in RV's. Quite often CG 50A isn't correctly phased (newer CGs are, but older CGs pull two legs from whatever is available). But it doesn't matter as RV 50A is treated as two separate circuits with all 120vac appliances divided between the two circuits. Front AC and MW. Rear AC and hot water heater.
I might be missing what you are attempting to achieve, but without major electrical modifications and expense, you cannot "add" 50A to a 30A RV. However, thats sorta what you do when using a 50 to 30A adaptor. The distribution panel becomes the weak link as the the 50A pole breaker is not correct for a 30A RV. Your only using one leg of 50A when adapting at the pole.
That said, there's no harm in increasing the shore cable capacity. Marinco offers super nice 3 wire connectors for removable shore power.
Good as it gets.
YMMV! JR

[mwdilday]

I saw a good suggestion where someone put a panel in the storage compartment for the 50 amp and then fed the 30 amp panel from that. The second A/C was wired into the new panel and nothing else had to be changed except a new plug and cord.

[SailorSam20500]

Originally Posted by JRBME

Quite often CG 50A isn't correctly phased (newer CGs are, but older CGs pull two legs from whatever is available). But it doesn't matter as RV 50A is treated as two separate circuits with all 120vac appliances divided between the two circuits.

If you run into a park that has done this - two 50 amp feeds on the same phase, they should immediately be reported to the town inspector. This WILL result in the neutral leg of your power cord being severely overloaded - potentially carrying near 100 amps. I suspect that this is one thing a good EMS checks for and will not allow a connection if it occurs.

[sdowney717]

Originally Posted by JRBME

50A service is typically two totally separated 120vac circuits. It isn't 'one' 50 A circuit. It would resemble a 240vac setup, but the two circuits(legs) don't commingle so you have two separate systems with no 240vac pitential. Usually front air conditioner on one leg and rear on the other.
Unless you rewire the RV in order to take advantage of the two 120v circuits, it won't help much.
You cannot combine the two 50A circuits....that would be 240 and uncommon in RV's. Quite often CG 50A isn't correctly phased (newer CGs are, but older CGs pull two legs from whatever is available). But it doesn't matter as RV 50A is treated as two separate circuits with all 120vac appliances divided between the two circuits. Front AC and MW. Rear AC and hot water heater.
I might be missing what you are attempting to achieve, but without major electrical modifications and expense, you cannot "add" 50A to a 30A RV. However, thats sorta what you do when using a 50 to 30A adaptor. The distribution panel becomes the weak link as the the 50A pole breaker is not correct for a 30A RV. Your only using one leg of 50A when adapting at the pole.
That said, there's no harm in increasing the shore cable capacity. Marinco offers super nice 3 wire connectors for removable shore power.
Good as it gets.
YMMV! JR

So trailer power campsites is different from marina power and house power? Most marinas with 50 amp service is setup just like your house, 2 hots and a single neutral. I thought it was the same, I mean why not? You still can not get 100 amps by combining the 2 hot legs.

[BandJCarm]

Picture.

[JRBME]

Originally Posted by BandJCarm

Picture.

A shore powered boat using 50A is a different animal in comparison to an RV. Many larger boats are wired for 220(240) and have 220 air conditioners, 220 battery chargers, and might have a 220 fridge. "Chassis" battery volt 24 or 48vdc. And, they have 220Vac gensets. And boat wiring is everything in between too. .
RV electrical systems evolved differently. Started with 15 or 20A, (or even no amps and gas lighting) then went to 30A. The only real " house" styled 220A RVs are the race track styled Prevosts and MCIs. Most large, modern CGs can supply 220 for these units. Tom Johnson Campground (Camping World) at CMS in Concord does. However, irregardless of the 220v in the pole, pretty much all stick'n staples use two 120Vac circuits. It's the same pole, just applied differently. The differences should be clearly understood before attempting to create an electrical system from scratch.
RVIA electrical codes will offer insights. Unless one installs home style AC or heat pumps, home style range or hot water heater, 220v is useless. Notwithstanding, using these appliances will limit your camping experience. You will be limited to proper 220Vac campsights or run your 220 generator. If plugged into 30A, the 220 appliances are useless.
RVIA codes are your friend. There are so many ways to screw up an RV electrical system if not well versed on RV systems...RVs are not the same as boats or home wiring. Don't let the smoke out! ;o)
I might ask why 220?

Cheers, JR

[sdowney717]

Originally Posted by JRBME

A shore powered boat using 50A is a different animal in comparison to an RV. Many larger boats are wired for 220(240) and have 220 air conditioners, 220 battery chargers, and might have a 220 fridge. "Chassis" battery volt 24 or 48vdc. And, they have 220Vac gensets. And boat wiring is everything in between too. .
RV electrical systems evolved differently. Started with 15 or 20A, (or even no amps and gas lighting) then went to 30A. The only real " house" styled 220A RVs are the race track styled Prevosts and MCIs. Most large, modern CGs can supply 220 for these units. Tom Johnson Campground (Camping World) at CMS in Concord does. However, irregardless of the 220v in the pole, pretty much all stick'n staples use two 120Vac circuits. It's the same pole, just applied differently. The differences should be clearly understood before attempting to create an electrical system from scratch.
RVIA electrical codes will offer insights. Unless one installs home style AC or heat pumps, home style range or hot water heater, 220v is useless. Notwithstanding, using these appliances will limit your camping experience. You will be limited to proper 220Vac campsights or run your 220 generator. If plugged into 30A, the 220 appliances are useless.
RVIA codes are your friend. There are so many ways to screw up an RV electrical system if not well versed on RV systems...RVs are not the same as boats or home wiring. Don't let the smoke out! ;o)
I might ask why 220?

Cheers, JR

why 220 -240 vac? Why does Europe use it for everything? Efficiency reasons , cost of copper wiring. A much smaller wire gauge can be used with higher volts.

My boat has twin 30 amp power. I rewired completely the entire AC with new wires and boxes and relays and switches. I have a 50 amp adapter that uses 4 wires, 2 hots, a neutral, a ground. A marina will have 240 vac pedestals if its a marina for bigger boats which use more power. They split the 2 hots on different phases so they can be combined, BUT some old marinas did have single 50 amp 120 vac plugs, but that stuff is just too old. My boat has no 240vac appliances its only 37 feet.

[mwdilday]

NEVER protect a 30 amp plug/receptacle with a 50 amp breaker. If you are upgrading to 50 amps you MUST make sure that everything in the system is rated for 50 amps. Failure to do this could cause a failure and worse a fire.

[sdowney717]

Originally Posted by mwdilday

NEVER protect a 30 amp plug/receptacle with a 50 amp breaker. If you are upgrading to 50 amps you MUST make sure that everything in the system is rated for 50 amps. Failure to do this could cause a failure and worse a fire.

You can send down higher volts on a wire but not higher amps, you could have a higher voltage like 240vac instead of 120vac and the higher volts device would use 1/2 the amps compared to the lower 120vac device, that is a big advantage right there in materials cost as the wire will be smaller but can do the same work as the bigger wire. The max amp rating of the wire never changes.

[JRBME]

Originally Posted by sdowney717

You can send down higher volts on a wire but not higher amps, you could have a higher voltage like 240vac instead of 120vac and the higher volts device would use 1/2 the amps compared to the lower 120vac device, that is a big advantage right there in materials cost as the wire will be smaller but can do the same work as the bigger wire. The max amp rating of the wire never changes.

Ergo, the European 50hz service. And lots of other countries.