Circuit tester question

[Rich_in_Tampa]

I'd like to routinely check shore power for polarity, voltage, grounding before plugging in my coach line. I have a 120v tester which works fine in any of the coach 120 v outlets.

But I'd like to test the 50 amp outlet. So, if I plug in a 50 amp adapter cord, and use adapters to take it to 30, then to 15 or 20 amps w/ standard residential plug, will the circuit tester I have a) blow up, b) accurately reflect the voltage, grounding and polarity at the 50 amp receptacle, c) not do the job.

The 50 amp surge protector/polarity/voltage gizmos I have seen are in the $350 range. I'll spring for that if it's the only way to be safe, but I wondered if I don't already have what I need (except for surge protection of course).

And lastly, recommendations for the 50 amp all-in-one surge protectors/circuit testers are welcome, esp if they can also work with 30 amp shore power.

This stuff is confusing - be gentle with me .

[tquarles]

Both (B) AND (C).

Since the 50 amp outlet provides 50 amps at 220v or equivalently, 2 circuits with 50 amps each at 110v, your 50->30 converter only connects to one side of the original 50 amp circuit, so you're accurately testing the half of the circuit that you're connected to(voltage, polarity, and grounding). Unfortunately, you have no idea what is happening on the other side. For that, you'll either need an actual 220v tester OR another 50->30 converter that is wired to connect to the other half of the 50 amp circuit and then test that one separately. Don't know where to get such a unit, but then I'd probably make my own.

You still won't know if you have REAL 220v power or just 2 110V 50 amp circuits, but then, unless you'll be using enough power to worry about the current in the neutral wire of your power cord and the pedestal, you should be good since I don't know of anything in typical RV's that actually uses 220v.

[RustyJC]

If you purchase an inexpensive multimeter, you can check the 50 amp shore power pedestal socket as follows:

L1 to N = 120VAC

L2 to N = 120VAC

L1 to L2 = 240VAC

Whether you have any 240VAC appliances or not, it is extremely important that L1 and L2 are 180 degrees out of phase if you are going to be using both legs of the 50 amp service. This is because neutral currents are additive, so if one were drawing 50 amps on both hot legs and the legs were in phase (L1 to L2 = 0VAC), the neutral leg current would be (50 + 50) = 100 amps applied to a conductor sized for 50 amps. This can result in a meltdown and electrical fire. Conversely, if L1 and L2 are 180 degrees out of phase, the neutral leg current when both hot legs are drawing 50 amps would be (50 + (-50)) = 0 amps, and the worst case neutral leg current when one hot leg is drawing 50 amps and the other drawing 0 amps would be (50 + (-0)) = 50 amps.

On the other hand, if you're only using the 50 amp shore power socket to power 120VAC 30 amp service, then at the female (30 amp) end of your 50-to-30 dogbone you should see:

Hot (could be L1 or L2, depending on dogbone wiring) to N = 120VAC

Rusty

[Route 66]

Testing before you plug in is never a bad idea, however you are unprotected after that.

Many of us use the EMS-HW50C which provides constant protection and it will work on a 30 amp circuit.

[Rich_in_Tampa]

Thanks, Dirk. The installation page on their web site is down. I am not at all handy with electrical work - I assume it would not be too complicated?

What do you think of their portable surge protector (ems pt50c)?

[RVDude]

Both Progressive Industries and SurgeGuard (generally the 2 industry leaders) make permanent (hard wired) and portable (inline) models.
http://www.rvupgradestore.com/index....S&Category=236
is an excellent source.

[Route 66]

Quote:

Originally Posted by Rich_in_Tampa Thanks, Dirk. The installation page on their web site is down. I am not at all handy with electrical work - I assume it would not be too complicated? What do you think of their portable surge protector (ems pt50c)?

The portable unit is just as good as the hard wired unit, however some folks have concerns that it could be easily stolen, but I don't recall anyone posting of that actually happening. The metal plate on the top wire is for a cable/padlock.

The 2 advantages of the hardwired unit are;

You can't forget to use it and the indoor display.

If you aren't comfortable with hard wiring the unit then I suggest having it installed or going with the portable unit if the indoor display is not important.

[RonBoyd]

Quote:

Originally Posted by RVDude Both Progressive Industries and SurgeGuard (generally the 2 industry leaders) make permanent (hard wired) and portable (inline) models. http://www.rvupgradestore.com/index....S&Category=236 is an excellent source.

Rich,

Another source is Tweety's.

http://www.tweetys.com/rv-surge-protectors.aspx

or more specifically:

http://www.tweetys.com/progressive-i...rotectors.aspx

The first "add-on" I purchased was the EMS Portable. The very first campground I stopped at had an "Open Ground" fault. In the past year, I have found three campgrounds with low voltage, one with extremely high voltage and one with the polarity reversed. (Interestingly, in each case I was told that "nobody else had complained" -- inferring, I suppose, that I was mistaken.) Consequently, I feel this was the "best money" I have ever spent -- for example, the hidden savings I will realize from not operating the AC unit with low voltage.

I purchased the "portable" unit primarily so that I could "take it with me" when a new RV is called for. I have it in-between the RV and the shore power cord -- inside a compartment in my RV. YMMV.

[wa8yxm]

The circuit tester you have will work properly but you will only be testing one side

I plan on building a "Break out box" tester that will test both lines for polarity, make sure they are indeed L-1 L-2 not L-1 L-1 (or 2/2) and provide a test point for my plug in volt-meters (Kill-a-watt) among other things.

I can tell you how to build it if you like

Two pigtails (one male, one female) a box big enough to hold all the wires, a colleciton of Neon indicator lamp assemblies a couple of fuses or breakers and some outlets.. Singles are best here.

[Rich_in_Tampa]

Wish I was as talented as you guys, electricity wise. Looks like I'll pop for the $350 device with surge protection as recommended. I haven't found much discounting.

Heck, with the amount the typical MH costs, what's another few hundred on safety items like circuit testers, tire pressure monitoring. Thanks for the tips.

[REWahoo]

Quote:

Originally Posted by Rich_in_Tampa Wish I was as talented as you guys, electricity wise. Looks like I'll pop for the $350 device with surge protection as recommended. I haven't found much discounting. Heck, with the amount the typical MH costs, what's another few hundred on safety items like circuit testers, tire pressure monitoring. Thanks for the tips.

I see you've been assimilated - resistance is futile.

The Progressive Industries unit is a good one. I opted for the hard-wired unit and found installation to be pretty straightforward. So simple a cave doctor could do it.

[Rich_in_Tampa]

Cave doctor...evokes images of a black hole, which I can see an big MH becoming very quickly .

So what's involved in installing the hard-wired one? The only advantage I can see is that it's less likely to be ripped off, though the portable one apparently has an optional hasp, too.

BTW, the DW loved the MH on our first outing. This is a big, positive change.

[wa8yxm]

Quote:

Originally Posted by Route 66 The 2 advantages of the hardwired unit are; You can't forget to use it and the indoor display. If you aren't comfortable with hard wiring the unit then I suggest having it installed or going with the portable unit if the indoor display is not important.

I will second that YOU CAN NOT FORGET TO USE IT!!!

Beyond a doubt that is the #1 reason to have a hard wired unit.. I have a Hughes Autoformer.. One park I found I really needed it.. Wind was blowing (Like 100mph, I'm not kidding here, weather service reported 90mph sustained with gusts well over 100 that evening and I did not feel like hauling it out and plugging it in... Had to use a work-around (which worked fine)

Now it's hard wired

However the portable has an advantage too.. When you trade up you just move it to the new rig

Oh, and if you choose to "install" it later. A hughes auto-former install kit works for those too

(SO you know the "kit" consists of a 50 amp plug, socket and some wire, that's all)

You don't get the indoor display (less you put it where you can see it, not easily done on my rig) but you can still pull the plugs, plug the rig into itself and put it in your new rig easily.

[REWahoo]

Quote:

Originally Posted by Rich_in_Tampa Cave doctor...evokes images of a black hole, which I can see an big MH becoming very quickly .

I'm going to rely on my 5th Amendment rights and not respond to this blatant attempt to incriminate me.

Quote:

Originally Posted by Rich_in_Tampa So what's involved in installing the hard-wired one?

Not a lot. If you've ever changed out an electrical switch in your house you have the essential skills to install one of these - very similar process on a slightly larger scale. I've seen a couple of photos on this and other RV forums walking you through the install.

Quote:

Originally Posted by Rich_in_Tampa The only advantage I can see is that it's less likely to be ripped off, though the portable one apparently has an optional hasp, too.

Wa8 gave a good response above. I'd also add having it hard-wired results in one less thing to have to fool with each time you hook up and un-hook. Not that you would ever forget anything of course....

Quote:

Originally Posted by Rich_in_Tampa BTW, the DW loved the MH on our first outing. This is a big, positive change.

Excellent! Always nice when the boss approves of your efforts.