How to wire a voltmeter?

Here is a nice unit that will notify you of polarity and grounding problems...
http://www.amazon.com/Prime-Products-12-4058-Power-Monitor/dp/B000BRFTH6/ref=pd_sim_60_4?ie=UTF8&dpID=514gFS4w61L&dpSrc=sims&preST=_AC_UL160_SR117%2C160_&refRID=0HSF9DXCVJZSZ4CJENH3

Depending on the meter it will have 2,3 or 4 leads

If 4 leads likely one pair will be red/black, the other .. Brown or some other color.

This would be an AC meter.. Designed for 120 volt

The red lead gets a positive DC voltage, may be 12, may be 5. The black lead is DC Ground. The other leads AC, that simple.

I doubt you will find a 120 volt in that style.. You might find a 12-20 volt

Use a transformer.. I can even make a DC meter work for that job but that takes me more time to type (And many published AC-lower voltage DC diagrams exist)

CJW8 wrote:


This will not monitor power. You would need a watt meter to measure power. This will measure AC volts only.

He must've misspoken. Half members here won't tell you the difference btw power, energy and potential.

Agreed with Mex - Brok is better brand. Something like This meter. They have meters for "power" i.e. watts, too.
Make sure it's not facing your bed, preferably not visible from bedroom at all. I don't have bright displays in my trailer and wouldn't want to.

downtheroad wrote:
I'm thinking of installing something similar to this to monitor the AC power in our new trailer. I don't want the 'plug in' type. Would rather have a small permanently mounted hardwired panel.

Question: How do I wire it and to what? Thanks.

This will not monitor power. You would need a watt meter to measure power. This will measure AC volts only. As several have suggested, a plug in voltmeter would be easiest. If you don't want a plug in, than you'd have run two wires from the back of desired meter and land them on an AC source which could be a spare breaker in your main panel or jumper them on to an duplex outlet somewhere. Since it is AC, polarity shouldn't matter but I'd land white on neutral and black on hot just to be sure.

My kill-a-watt meter agrees well with a Fluke. I'm good to go for 120 volt and also have a Hall Effect watt meter for monitoring all use in my Class C. 12 volt is not nearly so critical for me so I use a plug into the cigarette lighter that does xx.xx. Close enough to let me know what is what.

The only item I have that is at all hard to measure is a Nuwave 2 induction cooker. It jumps in wattage a LOT. I can't track it with the hall effect unit and the kill-a-watt can't keep up with the changes either. The only time it doesn't "hop" is I have it on the maximum setting.

Big Katuna wrote:
Not true. Copper has losses that increase with load and that drops voltage.Add in a bad connection and you can measure 120 at the pedestal and 108 at the AC compressor.Turn everything off and the voltage will rise to 120.

You're getting off track. OP is talking about a voltmeter installation inside the coach, not at the pedestal. Nor are we talking about whether it's 120..or any other specific number.

The voltage reading inside won't be exactly the same everywhere, but it's certainly close enough for any voltmeter. If the ac is on, and the voltage at the coach is 108, it will measure 108 at any outlet in the coach. That's the point I'm trying to impress to the OP...for practical purposes it doesn't really matter where he connects it.

OK?

I've got a drawer-full of "ballpark accuracy" LED and LCD meters. Wanna get one that reads 12.4 volts when voltage is really 12.75? Got one for you! Wanna get one that reads 13.08 when voltage is 12.86? Got that too!

Five meters, 110.7 VAC range from 101.2 volts to 122.4

Don't wait! Fix your voltage NOW! Too low? Gotcha covered. Too high? No problemo! What you see is what you get!

No, they don't have a pot on the back.

I've switched to DROK brand.

I did calibrate my "master" DMM on a $14,000 Tektronics Oscilloscope. So it's a decent reference for the next couple of months.

How would a person like online banking with errors like that?

$330.00 Balance.
Just kidding! You have overdrawn seven times at $35.00 a whack.

Lights go out? Too low of voltage.
Smell sulfur? Too high of voltage.

Funnier 'n a Mexican Stop Sign...

downtheroad wrote:
I already have a plug in type and it works just fine... I'm just bored and am thinking of projects while I wait for our new trailer

Don't worry, you will have SO many things to fix in your new trailer that it will keep you busy for a few seasons.

If all you want is the AC voltage - plug in type is enough.
If you want to make something nice looking, install that cheap Ebay meter flush in the wall and hard-wire to the nearest AC receptacle.

I tend to overthink and overdo my projects, that's why I wrote about poor quality of cheap meters. For DC battery volts they are - usually - worthless, not any better than LED Christmas lights on the OEM panel that reads battery 100-50%-0. For 120 VAC it will do.

2oldman wrote:

jmckelvy wrote:

2oldman wrote:
to any 120v source. Voltage is the same everywhere.

Only if everything is turned off. :)

It's the same everywhere no matter what is off or on.

Not true. Copper has losses that increase with load and that drops voltage.

Add in a bad connection and you can measure 120 at the pedestal and 108 at the AC compressor.

Turn everything off and the voltage will rise to 120.

IMMHO
Sometimes receptacles aren't located for the ideal viewing angle.
I have receptacle type AC voltmeters that not only use one receptacle they hide the other receptacle. Duh?

Any meter should have a fuse. This morning, I had a coffeemaker malfunction and FLAMES shot up from the Formica and from the plastic coffeemaker. Genuine Mexican house. A single 30amp breaker protects the entire structure. Wooden house and 30 mph wind this morning. If I hadn't been there I would have returned to a charred crater. "CLICK! CLICK! CLICK!" then smoke and flames rolled out. I now have an 18" ceramic tile paying atop the 8" circular char on the counter top.

I have seen AC meters, especially the five-and-dime variety Chinese meters flame. It's ugly. A 1-amp fuse would protect an AC meter.

DROK® meters seem to be a cut above the rest. The cheap meters not only are inaccurate they have a sampling rate that is far too slow for me. A slow sampling rate makes the LED numbers seem to jump when voltage changes. My DROK meters have a separate + and - for the LED display. This allows for dimming if needed.