Community Forums

abarkl · 11-16-2005, 05:19 AM

I'm trying to get AC power to my rig in a family member's driveway. I've connected my 50 to 30 to 15/20 amp extension cords, but no go. I've checked and found one leg of the 50 amp cord hot coming into the rig, but I don't get any AC inside or at the EMS. If I crank up the genset everything's good, and I had it plugged in to shore power just last week.
If there wasn't enough amperage or voltage at the family member's outlet I just wonder if my transfer switch or EMS would shutdown?

abarkl · 11-16-2005, 05:19 AM

I'm trying to get AC power to my rig in a family member's driveway. I've connected my 50 to 30 to 15/20 amp extension cords, but no go. I've checked and found one leg of the 50 amp cord hot coming into the rig, but I don't get any AC inside or at the EMS. If I crank up the genset everything's good, and I had it plugged in to shore power just last week.
If there wasn't enough amperage or voltage at the family member's outlet I just wonder if my transfer switch or EMS would shutdown?

Richard and Babs and a Bob Tail Cat · 11-16-2005, 05:33 AM

Could be a bad adaptor. We go 50 to 30 to 20 at my brothers house. We then keep the frig on gas and turn off the batery charger and can run one AC off of a 20 amp service. Try another plug also as the one you are plugging into may be wired incorrectly.

If you are on a 15 amp breaker you may not be able to run your AC unit with the other loads. You also cannot plug into a GFI.

Dsouthw524 · 11-16-2005, 05:54 AM

Just a warning that your unit may trip a GFI at the house where you are connected. Some of the power units will cause this.

RustyJC · 11-16-2005, 06:16 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by abarkl:
I've checked and found one leg of the 50 amp cord hot coming into the rig.... </div></BLOCKQUOTE>If that's the case, then something's wrong with your adapter setup or 50 amp power cord. 50 amp service provides 2 hot legs that are 180 degrees out of phase. Each of these hot legs powers a separate bus in the 50 amp RV's power distribution panel. The 50-to-30 adapter should connect the 2 50 amp legs on the RV side to the single hot leg on the 30 amp side. This jumpers the 2 each 50 amp buses in the RV power distribution box together so that all loads will have access to power. If only 1 leg is hot coming into the RV, then whatever is on the dead bus in the 50 amp RV's power distribution panel isn't going to work.

Rusty

Tom N · 11-16-2005, 02:14 PM

Check for reversed polarity at the outlet on your friends home.

abarkl · 11-16-2005, 04:05 PM

It must have been an issue with GFI or polarity. I'm plugged into another outlet and pulling 13-15 amps with a space heater and 12V charger.
Thanks for the help!

Gary RVRoamer · 11-16-2005, 04:37 PM

RustyJC has hit the nail on the head - the adapter isn't power BOTH legs of the 50A power cable. And with only one leg powered, a lot of circuits in the Rv aren't going to work.

If you can flip the 15A adapter over, it will swap which of the two bus bars in the coach are powered and chances are most of the interior circuits will work then. In some Rvs only the rear air and maybe 1-2 other things are on one bus and most everything else is on the other.

AS Tom N. says, the house circuit may have polarity reversed - that's not unusual. But that affects only which 50A keg is powered and the 50/30 adapter should be powering BOTH of them. Since changing to another outlet enabled different circuits in the RV, polarity is definitely what changed. But that does not fix the problem with your 50/30 adapter.

abarkl · 11-17-2005, 06:00 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Since changing to another outlet enabled different circuits in the RV, polarity is definitely what changed. But that does not fix the problem with your 50/30 adapter. </div></BLOCKQUOTE>

Does anyone know how to test one using an ohm meter?

RustyJC · 11-18-2005, 03:29 AM

Disconnect your adapter setup from AC power. Take the 50 to 30 adapter and place one probe of the ohmmeter on the male hot leg terminal of the 30 amp side of the adapter. Placing the other probe of the ohmmeter into either of the 2 female hot leg terminals on the 50 amp side of the adapter should show continuity (0 ohms). All other terminals on the 50 amp side (neutral and ground) should show infinite resistance.

Rusty

Stretch · 11-18-2005, 05:11 PM

well everybody has a diagnosis for this problem. So here goes my idea. Make up an adapter consisting of a 50 amp female plug and two 20 amp male plugs. Connect each 20 amp plug with a three conductor cord to each hot side of the 50 amp female receptical. Then plug each of the two twenty amp plugs into a different 20 amp female plug (that is on a different circuit breaker)in the house or garage or wherever there is power.
This method will work well because most motor homes do not have a typical 50 amp 220 volt system. What the normal coach has is 2 seperate 115 volt circuits. These circuits never are used together like in a 240 volt oven or A/c unt or a motor. So you really do not have to be concerned that you are really using the same 120 volt leg of the house current. Anybody disagree?

RV Wizard · 11-19-2005, 12:27 AM

All 50 amp serviced coaches are feed from shore power with a 120/240 single phase 60 Hz current. Most do not use 240 volt apparatuses and therefore do not need double pole breakers. There are some that are using a 120/240 volt dryer and those units will use the double pole breaker. Your adapter made with 2 20 amp plugs will work on all coaches not needing 240 volts. It will even provide 240 volts if the two 20 amp circuits you are pluged into are on opposing legs of the house wiring you are plugged into.