50 amp to 15 amp - now I'm confused

[Gordie Allen]

I thought I knew what was going on until today. I have a 50 amp shoreline coming into a panel with two 50 amp breakers. From there the black, white, and bare (ground) go through a Multiplus inverter and then to one side of a typical 240 panel. The red wire bypasses the inverter and goes directly to the other side of the main panel, so I have two bars carrying 120v. I don't have any 240v loads. The idea was to have a second 120v for a second A/C unit and luxuries only to be used when I had access to 50 amps. It has worked fine for two years. Today I dropped the bus off at a repair shop and was going switch on my block heater which has a 15 amp breaker on the red (non-inverter) side of the main panel. I have a 50 amp to 30 to 15 adapter which I've never used. I got ready to plug it in, and thought somewhere in the 50 to 15 amp plugs the red (or black) line must be dropped and if so which side of the 50 amp plug still carried the 120v down to the 15 amp plug? Realizing I had not encountered this before, I opted to splice the single block heater cord to a standard 120v 15 amp cord and bypass everything going directly from the 15 amp shoreline service to the block heater. When going to 50 amp to 30 amp, is one hot leg of the 50 amp dropped? I didn't have a multimeter with me to see if only one bar of the main panel was carrying 120v. Breakers on both sides of the panel appeared to be dead when plugged into to 120v 15 amp outlet in the bus. I read several Archive articles and just got more confused. Now I'm afraid I need to do a complete rewire of my shoreline setup. Help!

[sparkplug188]

When going to 50 amp to 30 amp, is one hot leg of the 50 amp dropped?

All of the 30a to 50a adapters I have seen are wired like this:



The adapter sends 15a (or 30a) 120v to both legs of the 50a receptacle.  All 120v loads should work.  If you had 240v loads, they would not work with the adapter because both legs would be tied together and in phase with each other.

Breakers on both sides of the panel appeared to be dead when plugged into to 120v 15 amp outlet in the bus.

Do both sides of the panel start working when connected to standard 50a 120/240v shore power?  If everything works without the adapters, suspect a problem with the adapters or with the 15a receptacle the adapters are plugged into.

[brmax]

Here is something i found along the lines of the RV plug (tt-30R) we see a bit, hope that helps.

http://www.rvpowerprotection.com/Links_files/30-amp%20Service.pdf

[Debo]

Check the adapter with a multimeter. I bought one that is wired to only supply power to one leg of the 50 amp service. It's basically worthless for my purposes.

[bobofthenorth]

Gordie your setup sounds fine to me.  The drawings already posted match how any adapters I have ever used were wired.  Are you sure you were plugged into a good outlet?  That would be my first suspicion followed by a defective adapter.  Another possibility would be that the outlet you were using was GFI protected.  With your inverter wired in pass through it could trick the GFI into tripping before the inverter bond lifts.

[Gordie Allen]

Thanks all,
That first diagram explains everything. When I get back to the bus I'll check out the adapters. Much relieved as this is one area where everything has to be right.
Thanks again
Gordie