50 amp service problem

[ShapeShifter]

Originally Posted by Alan_Hepburn

Even if we try to make contact with all 4 prongs at once it almost never happens. With that in mind, if the outlet is "live" when you're plugging in (or unplugging) bad things WILL happen. That is why you ALWAYS make sure the breaker in the pedestal is OFF before you plug in, or unplug.

That's good advice. A properly installed EMS can help with that. The normal state is to have the power going to the coach disconnected. Then when you plug in, only the EMS is exposed to the pedestal problems, and its designed to handle most issues. It will validate the power, and will only connect power to the coach if its good for 15 seconds (or 2 minutes, depending on settings.) So the coach appliances won't see the effects of a momentary open neutral while plugging.

It's always safest to switch off the breaker, but the EMS will cover your back if you forget.

[flaggship1]

Originally Posted by "007"

Get some good instructions on how to correctly use all that you have showing, a simple job is now a project in the making.
If you get into trouble try this link and maybe it will help to get out of trouble.
The Amish install is the best thing you have going for you.

A very informative and useful collection of links to all sort of technical information. Thanks for sharing! If I didn't have to go to work now, I could read for hours.
Thanks, Steve

["007"]

A

little extra help for piece of mine and a happy camper.

[Dr4Film]

Originally Posted by Happy Prospector

As a Troubleman for a Electric Utility for over 15 years, using a voltmeter and checking for a open or compromised neutral without putting a load on the circuit doesn't always work.

When we would check a voltage complaint at a customers house we ALWAYS put a load on the service before checking voltage. I have seen too many people check voltage on a circuit with no load on it and it looks good, add a load to it and the voltage would change.

Do it right the first time and save yourself some grief.

I am no professional electrician and I know enough about this stuff to be VERY dangerous to myself but I don't see how by putting a LOAD onto the incoming 100 amp service, 50 amps each leg, will determine whether you have no neutral or no ground. I can understand where having a load will effect your voltage levels but when you do your initial test, either you have a good neutral and ground or you don't.

Where the Progressive Industries EMS HW-50C device shines and does it job correctly is when either the neutral or ground is temporarily lost AFTER plugging the RV into the pedestal. It will sever the shore power in about 18 ms if I remember that number correctly.

I have had that happen at a RV Park and didn't know it until I looked at the display sometime later where it will list any PE codes which stands for Prior Error codes. I have had them for various things including lost grounds and neutrals. Having a lost ground is not too serious unless you are standing on wet ground and then touch a metal portion of the RV, HOWEVER losing the neutral will destroy many electrical devices QUICKLY as they cannot handle 240 VAC going through them.

I think the portable device I had referenced earlier to check the pedestal for all facets of the power, open neutral, open ground, voltage levels, fake 50 amp legs, etc. is a great device to quickly check the pedestal. If the voltage is too low because I haven't put a load on it, well that's why I have my PowerMaster VC-50, it will boost the low voltage to acceptable levels.

Just my opinion.

Dr4Film ----- Richard

[ShapeShifter]

Originally Posted by Dr4Film

I am no professional electrician and I know enough about this stuff to be VERY dangerous to myself but I don't see how by putting a LOAD onto the incoming 100 amp service, 50 amps each leg, will determine whether you have no neutral or no ground. I can understand where having a load will effect your voltage levels but when you do your initial test, either you have a good neutral and ground or you don't.

I am also not a professional electrician, but I am an engineer. There is indeed a gray area between having a good neutral or not: you can have a corroded or loose connection. That can manifest itself a few ways:

• It could have some resistance to it, which generates a voltage proportional to current. With no load, there is no current, and therefore no voltage drop - so all of the voltages read correctly. But when you put a load on it, the resistance generates a voltage drop - if it's on the hot lead you could get reduced voltage to your rig, if it's on the neutral lead it could affect the balance of voltage between the two legs.
• It could manifest as an intermittent connection that opens up when it heats up. If that happens on a hot leg, you lose that leg, but if it happens on the neutral you could lose the appliances in your rig.

I'm sure there could be other failure modes, as well.

[Route 66]

With no load the RV service will measure 240v from L1 to L2 and 120v from L1 to ground or neutral and 120v from L2 to ground or neutral.

In RV service with a bad or compromised neutral, the neutral is unable to carry any or little current. With a bad neutral, a load on L1 or L2 will cause a voltage drop on the side with the load and a voltage increase on the side with no load.

The two sides or lines will always add up to 240v. If a load on L1 with a bad neutral causes a 50v voltage drop (not unreasonable) from 120v to 70v, then L2 will measure 170v.

With a bad neutral, the voltages will fluctuate from high to low depending on the loads on each leg of the circuit at any given time.

Testing before plugging is better than nothing, but is of no help during the course of your stay as other campers plug in and loads change. Most electrical service problems occur after you are connected.

A device like the Progressive EMS constantly monitors the service and will disconnect if voltages are too high or too low.

Originally Posted by Dr4Film

I am no professional electrician and I know enough about this stuff to be VERY dangerous to myself but I don't see how by putting a LOAD onto the incoming 100 amp service, 50 amps each leg, will determine whether you have no neutral or no ground.
Dr4Film ----- Richard

[Dr4Film]

Originally Posted by ShapeShifter

I am also not a professional electrician, but I am an engineer. There is indeed a gray area between having a good neutral or not: you can have a corroded or loose connection. That can manifest itself a few ways:

• It could have some resistance to it, which generates a voltage proportional to current. With no load, there is no current, and therefore no voltage drop - so all of the voltages read correctly. But when you put a load on it, the resistance generates a voltage drop - if it's on the hot lead you could get reduced voltage to your rig, if it's on the neutral lead it could affect the balance of voltage between the two legs.
• It could manifest as an intermittent connection that opens up when it heats up. If that happens on a hot leg, you lose that leg, but if it happens on the neutral you could lose the appliances in your rig.

I'm sure there could be other failure modes, as well.

Originally Posted by Route 66

With no load the RV service will measure 240v from L1 to L2 and 120v from L1 to ground or neutral and 120v from L2 to ground or neutral.

In RV service with a bad or compromised neutral, the neutral is unable to carry any or little current. With a bad neutral, a load on L1 or L2 will cause a voltage drop on the side with the load and a voltage increase on the side with no load.

The two sides or lines will always add up to 240v. If a load on L1 with a bad neutral causes a 50v voltage drop (not unreasonable) from 120v to 70v, then L2 will measure 170v.

With a bad neutral, the voltages will fluctuate from high to low depending on the loads on each leg of the circuit at any given time.

Testing before plugging is better than nothing, but is of no help during the course of your stay as other campers plug in and loads change. Most electrical service problems occur after you are connected.

A device like the Progressive EMS constantly monitors the service and will disconnect if voltages are too high or too low.

Thanks Guys for the explanations. I am now a little smarter and even MORE dangerous than before.

This information is even more justification for everyone to have the Progressive Industries EMS unit to protect their RV's.

As for the homemade device used to plug into the pedestal to perform an initial check of the pedestal power, that would certainly be a time saver if something was seriously wrong with the power from the get go. Saves having to pickup and move to another site or sometimes even a different RV Park.

Dr4Film ----- Richard

[ShapeShifter]

Originally Posted by Dr4Film

I am now a little smarter and even MORE dangerous than before.

ROFL! Thanks, you made my day with that!

Originally Posted by Dr4Film

As for the homemade device used to plug into the pedestal to perform an initial check of the pedestal power, that would certainly be a time saver if something was seriously wrong with the power from the get go. Saves having to pickup and move to another site or sometimes even a different RV Park.

I suppose. But that's just one more thing to carry and maintain. Maybe I'm just lucky, but I haven't run into enough power problems to make it worthwhile. I can usually plug in early enough in the setup process that it's just as easy to plug in and check the EMS display (I have dual displays, one next to the shore cord reel, one inside.)

The biggest problem I've found is a dead outlet - not at a campground, but when setting up at a dog show where the power can be quite iffy - I usually have to spend some time looking for a breaker, and rarely have to get a maintenance guy to work on it. I think I've only ever wanted to move once because of power problems, but that didn't really help since the fluctuating low voltages were all over the campground.

I think checking the pedestal before plugging in is better than doing nothing, but the real value in the EMS is the continuous protection. Other than the occasional dead socket or minor issue when plugging in, all of the times that the EMS has tripped off on me has been due to problems that developed well AFTER I was plugged in. Almost always this is low or high voltage - it was good when I plugged in, but dropped later in the day. I was even at one place where it would soar to more than 140 volts in the middle of the night! I feel sorry for folks that didn't have something to automatically cut off the power, because even if they had a plug-in voltage meter, I'm sure they weren't watching it a two in the morning!

-- SS

[IMDSailor]

Originally Posted by Dr4Film

50-amp Tester

Dr4Film ----- Richard

Going to Home Depot get the parts for this today.

Thanks again for posting the link, and of course thanks to the guy who thought it up in the first place.

Stewart