Alfa Gold 38 - 50A Shore Power

[Epukerob]

Can anyone share/post a photo of the electrical panel - cover removed exposing the wiring?  I am trying to identify correct breaker circuits and positions inside the panel.  If anyone has a wiring diagram/schematic??  This system has 2 "hot" legs, each 110V, with 220V leg-to-leg, feeding the panel from the 50A shore connection.  There is a "Site Selector" switch inside the cabin - I am not sure how this functions ... or how it is wired.  Any knowledgeable Alfa brothers out there?

Best, Rob

 

[Gary RV_Wizard]

I think you now have the site selector answer, and the 50A service is pretty much RV standard 50A, which is also just like residential 240v power.  There will be an auto transfer switch that shifts the source between shore and genset automatically when the genset starts.

 

[Alfa38User]

I think you now have the site selector answer, and the 50A service is pretty much RV standard 50A, which is also just like residential 240v power.  There will be an auto transfer switch that shifts the source between shore and genset automatically when the genset starts.

No genset in an Alfa 5th wheel (at least a standard one) and thus no auto transfer switch!!!

There are actually 2 50 amps circuits available(120V each) for a total of 100 amps.  The 2 ( L1, L2) 120V legs each power 1 side (left and right side of the panel, lining up under the two 50 amp breakers, again 1 for each side) There is no wiring that connects both sides at once so they all remain 120V. You will note that for the AC, each compressor c/b appear separately, one on each side of the panel. Some c/b are not labeled nicely such as the washer-drier and microwave (at least on mine). There is a selector switch next to the microwave to allow you to select one OR the other using only one of the breaker positions, another concession to 50/30 amp potential dilemma. Since the AC compressors are controlled by the AC itself, the 30/50 amps site switch acts as the protection on that circuit against blowing the 30 amp campground supply c/b's.

Using a 30-50a dogbone adapter on a 30 amp site will allow both sides of the c/b panel to be powered so these protections against overuse of the available 30 amp campground power are required. NOTE that only 30 amps will be available under these conditions  compared to 100 amps on a "50 amp" site...

 

[Epukerob]

Hey Alfa - can you send/post up a photo of your panel (cover removed)?  Trying to figger out which breakers/circuits go where.

 

[Alfa38User]

Sorry, don't have one but check your email!!! I am presently 1800 miles away from it!! All the wire dives down under the floor behind it on the left as viewed from the front, except that used for the two fridge outlets directly behind them. AFIK.


You may have one breaker with a test button on it, that is a ground fault+breaker. It serves the outlets on the bathroom counter (2), kitchen counter(3), patio outlet and probably the microwave (outlet in the cupboard above it). Should you encounter no 120V power at any/all of those locations, simply reset the breaker and see what happens.

 

[NY_Dutch]

There's always the old school way of sorting it out. Flip off a breaker and see what quits working...

 

[SeilerBird]

There's always the old school way of sorting it out. Flip off a breaker and see what quits working...

That is a much better way. The wiring will not be necessarily the same from unit to unit.

 

[grashley]

Stu gave a good explanation of the 120V electric.  There is absolutely no standard for which circuit is wired to which breaker.  Even identical models may not be the same.  A picture of my panel will show how mine is wired and labeled.

As suggested above, turn off one breaker and see what does NOT work, then label it.

On my FW, I have separate breakers for:
Inverter
GFCI receptacles
Bedroom A/C
General - Cent Vac, LR TV, receptacles, Fridge AC, Bedroom AC
Living Room A/C
Main breaker (IN)
Main Breaker (IN)
Fireplace
Washer / Dryer
Water Heater
Microwave
Open slot

Maybe the list will help.

 

[Gary RV_Wizard]

Did he ever say it was a 5W vs motorhome?  Alfa made both...

 

[Epukerob]

Many
thanks to Stu, Dutch, Grashley, Gary, et. al.!  Just to clarify, it is
indeed a 5th wheel and not a motorhome.  So ... the breaker position in
the box can be important if the system is wired for 50A shore (220V = 2x
110V "hot" legs) or 30A @ 110V.  With adapters, one can connect to
both, BUT, if connected to 30A - 110V service, one of the "hot" legs is
dropped.  As a result, some breakers will go cold, depending on position
inside the box.  This is the purpose of the jumper inside the breaker
box.  I would surmise that most would never mess w/it ... can certainly
be dangerous!  In any event, I think I'm well on my way now thanks to
Stu and others here!  I wish everyone safe and rewarding travels!

 

[Lou Schneider]

With adapters, one can connect to both, BUT, if connected to 30A - 110V service, one of the "hot" legs is dropped.  As a result, some breakers will go cold, depending on position inside the box. 

It depends on the adapter.  The ones I've seen send the 30 amp hot lead to both hot pins on the 50 amp socket, so all of the rig's breakers are powered.

Of course, you're still limited to drawing a maximum of 30 amps total.

 

[NY_Dutch]

It depends on the adapter.  The ones I've seen send the 30 amp hot lead to both hot pins on the 50 amp socket, so all of the rig's breakers are powered.

Of course, you're still limited to drawing a maximum of 30 amps total.

Exactly... The only time I've seen a 30/50 adapter that only powered one leg was a homemade setup that came with the used motorhome. The fellow asked me to troubleshoot why so many outlets and appliances didn't work on 30 amps. A few minutes and a couple inches of wire fixed it...

 

[Gary RV_Wizard]

BUT, if connected to 30A - 110V service, one of the "hot" legs is
dropped.  As a result, some breakers will go cold, depending on position inside the box.

Not on any commercially made 50/30 adapter I've even encountered. They all split the single 30A hot to feed both 50A legs.  Powering only one leg borders on asinine - there is no guessing what functions might be lost with that approach.

The only reason to provide a 50/30 selector in the RV is to better manage when on 30A, e.g. disabling one a/c compressor as someone mentioned. Many RVs do that automatically based on the voltage between L1 & L2, but that has some shortcomings when connected to non-standard 50A sources.  For example, inverter generators often produce two hot legs that are in-phase, so no 240v even though they may have 35-50 amps per leg.  And I've been in campgrounds that provided twin-30A or twin 40A service on their "50A" sites

 

[grashley]

My FW is plugged into a 50A plug -->50A --> 30A adapter --> 30A cord -->  30A to 50A adapter -->50A cord --> camper right now.  All circuits are hot.  I am limited to 30 A, though.

 

[Epukerob]

Greetings All!  Ok, that is all great information ... and makes sense!  I get it now!  Have my 50A (220VAC) shore power drop cord in-bound now ... will keep all posted on developments.  I again thank you all for your invaluable contributions!!

Rob