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Power line monitor question

I am not an electrician.  Really not an electrician in any sense of the word. 

Given that, the coach is on the driveway plugged into a 15 amp outlet.  The inverter is turned off. The powerline monitor shows voltage on line 1 & 2.  See pic.

Can someone please explain this in layman terms?  I thought I should only see voltage on one line. 
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Mark & Mary Benko
Former coach: 2005 U295 3823
Jeep Cherokee, Honda Fit

Re: Power line monitor question

Reply #1 –
It depends on how the adapter is wired. It looks like yours is wired to supply power to both lines. You are still limited to about 15 amps total among the items consuming power, but power should be available to all of them. The neutral line on your 15 amp plug connects to the neutral line at the input to your coach. The hot line on your 15 amp plug is connected to both hot lines at the input to your coach. The usual configuration from Powertech generators also hooks a common 120VAC line to both lines of the wiring in the coach.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Power line monitor question

Reply #2 –
Looks like one of the green lights on the polarity check is either our or weak or out (mine are a combination of weak and out). Both circuits should read the same.

Also looks like one of the voltage monitor readouts is slightly out of calibration, as both circuits should read the same voltage since they connect together at the adapter.  There is a slight possibility the circuits do have differing voltages, but only if there is a much greater load on one or the other.  Personally, I would unscrew the panel and check the socket the panel plugs into with a voltmeter to see what's what, and adjust the trimpots on the voltage check circuit board.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: Power line monitor question

Reply #3 –
Simple.  The single hot in your 30 amp male connects to BOTH hots to 50 amp female end.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Power line monitor question

Reply #4 –
Thank you all gentlemen.  I have a much better understanding now.

Tom - The green lights do not line up with the holes in the panel exactly and the upward angle of the pic does not help.  Before I got the coach I read and bookmarked all the foreforum posts on fixing the dim lights and on calibration.  Everyone was so interested in the posts I thought when I got a FT mine would probably have that issue as well and it does! 

Now that I've finally got the coach home after 6 months of being on the road and storage in another state I'll be able to start on the project list.

Thanks all.  Learned something new today.     
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Mark & Mary Benko
Former coach: 2005 U295 3823
Jeep Cherokee, Honda Fit

Re: Power line monitor question

Reply #5 –
Related question.  As mentioned above, when I have the coach plugged into a 15amp wall plug with an adapter to the 50 amp plug, I get both voltages.  However, if I turn the circuit breaker off for the engine block heater (breaker #9 in our coach), I get "0" in the bottom window.  Why would this be?  Thanks in advance.

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George Hatfield

  Never ever use World Line Motors of Nacogdoches for service!

Re: Power line monitor question

Reply #6 –
Quote from: George Hatfield –
Related question.  As mentioned above, when I have the coach plugged into a 15amp wall plug with an adapter to the 50 amp plug, I get both voltages.  However, if I turn the circuit breaker off for the engine block heater (breaker #9 in our coach), I get "0" in the bottom window.  Why would this be?  Thanks in advance.


George,
The the outlet for the bottom power watch is on that same breaker 9.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Power line monitor question

Reply #7 –
Quote from: George Hatfield –
Related question.  As mentioned above, when I have the coach plugged into a 15amp wall plug with an adapter to the 50 amp plug, I get both voltages.  However, if I turn the circuit breaker off for the engine block heater (breaker #9 in our coach), I get "0" in the bottom window.  Why would this be? 

The power line monitor (at least in our coach) reads off one circuit of each 50 amp "leg".  Breaker #9 in your coach is probably on the circuit used to monitor the voltage on one of the legs.

We discovered this when after driving for a while on less than smooth roads, one leg of our PLM would show "0" when we plugged in.  At first we thought it was a park power problem, then we discovered the breaker tripped.  Turns out those breakers get tired as they age and don't hold with the heat of the engine and road vibration.  We've had to replace 3 of them in the past 2-3 years (different ones each time, the last one was for the rear A/C).  They're readily available at Lowes.

Michelle
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Power line monitor question

Reply #8 –
George,

I would relocate the feed wire for that leg of the monitor to another breaker on that same leg that you always leave on.

Should be a simple 2 minute job.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Power line monitor question

Reply #9 –
I'm late to this conversation, but the only time the voltages might be different is when plugged into 50 amps as that plug has 2 hot lines.  30 amp or anything else is only a single hot line.  The dog-bone adapter is internally wired to connect that single line to both hot lines of the 50 amp plug.  So why are you getting different readings on the different lines?  There could be a load on one line that is not on the other dropping the voltage on that one line.  Also if you measured the voltage on one line with 2 different volt meters it's very likely that you will get 2 different readings as most voltmeters may have a little error of 1 or 2 %.  Anyway 2 or 3 volts is not worth worrying about, but if you see a 10 or 15 volt difference, then some investigation may be in order.  If you are not an electrician or so inclined, be careful that stuff can kill you. 
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt