Multi-Meters ??

The other day I was checking out one of our generators here at the house. It's been giving me issues and I was trying to figure out what the issue is. In the process I did a couple checks with my multi-meter and got some weird readings. Not believing the readings I got initially I grabbed my amprobe which also has a multimeter built into it and did the same checks. Got different readings with this meter, and these readings seemed more in line with what I was expecting.

I wanted to check the frequency of the generator, but my amprobe meter doesn't have a frequency option like my other meter does. Suspecting a meter issue I brought my Fluke meter from work home to see what's going on. My Fluke and my amprobe meter agree with each other on all the tests I ran, but my home multi-meter is reading off on both voltage and resistance (and possibly capacitance too). I thought it might be a bad battery so I replaced the battery, same result.

In DC voltage I'm reading .5-.7 volts low (from the other two meters) on a 9 volt source, and about 6-7 volts low on an AC reading. Then I went and checked it on a 24 volt power supply (DC), and it's reading like 1-2 volts low. What's really strange is the meter is reading high on impedance compared to the other meters. So when checking a known resistance value I'm getting anywhere from .1 ohms high (which is a LOT) different from the other two meters.

My work Fluke has a frequency counter so I checked the generator and sure enough it's not generating 60 Hz consistently, sometimes dropping down to as low as 50 Hz when it takes a load (but it doesn't recover). Anyway, the point isn't about the generator, I know I've got work to do there. The question here is...why would a meter be reading different like this?

It's a trusty old meter that I've had for a long time. All indications are I should replace it, but it's like parting with an old and worn Carhartt jacket. I know I shouldn't let sentimental value get in the way of electricity, but I thought I'd check here and see if anyone has any thoughts?

Also, any thoughts on a new meter? I'm thinking maybe the Fluke 117 or the Fluke 87V Max (although that'll make me about $380 bucks lighter). I'm tempted to maybe get the Klein MM600, but it's gotten some mixed reviews. Any thoughts?

Why don't you send your old meter for recalibration.
Most can be fixed not sure yours can.
a reply to: Flyingclaydisk

a reply to: bluesman462002

That's a good idea, but the company has since gone out of business. If it was a bench meter, I probably would, but I imagine having a 3rd party recalibrate this thing would cost more than a new one.

Good suggestion though.

You could be right about cost but look for a local lab that does government recalabration.
Theres a small business close to me that does such and they always give me a very good price for the work.
May be one in your area and by the way i love my old test equipment.
Much better than some of the newer stuff.

a reply to: Flyingclaydisk

Why don't you send your old meter for recalibration.

Google up what you are looking for. We buy a lot of used calibrated equipment online with a warranty for half price.

a reply to: ShadowChatter

Very interesting!!

I just pulled mine apart and it has (3) of those variable resistors. I'll have to spend some time figuring out which one does what, but I honestly had no idea it was that simple! Makes complete sense now that I think about it though!

The meter i use is for automotive work, but is a Fluke. I will get some wonky readings when the battery is starting to go.
I know, simple but as with anything eliminate the most obvious first.

I have the Fluke 117 and it hasn't done me wrong. Really can't go wrong with Fluke...just pick the model that does what you need.

a reply to: Flyingclaydisk

All of our guys carry Fluke multimeters. We get very good service out of them.
In the old days I carried a Simpson 260 meter ( I am feeling like a dinosaur).
Simpson 260

Now tell us about you generator setup!!

LOL count me in i used a simpson 260 many times.
great meter
Still have that old dinosaur and works like new.
reply to: butcherguy

I almost forgot... Years ago, I bought an off brand multimeter that ended up blowing up about two feet in front of my face. I was checking for 480 supply voltage and the second that I touched my second probe, it blew up. It sounded like a shotgun blast. I blew the front cover off the meter, but I didn't get hit by anything. I had the meter dial selector set properly and the specs of the meter said that it was good for 750 volts.
I never bought a cheap meter again.

originally posted by: mikell

Now tell us about you generator setup!!

Which one? We have (3). The generator in question is a spare, and it's just a small one (7 kW). We use it for kind of a portable genset for various things.

I think you're probably more interested in how our bigger (35 kW) genset is set up, correct?

originally posted by: butcherguy
I almost forgot... Years ago, I bought an off brand multimeter that ended up blowing up about two feet in front of my face. I was checking for 480 supply voltage and the second that I touched my second probe, it blew up. It sounded like a shotgun blast. I blew the front cover off the meter, but I didn't get hit by anything. I had the meter dial selector set properly and the specs of the meter said that it was good for 750 volts.
I never bought a cheap meter again.

Wow! That's pretty crazy! Yeah, it's not worth it to buy el-cheapo meters, not when you're dealing with stuff that can kill ya!

I was talking with a guy just the other day who was telling me about some tweezer multimeter he bought on the cheap and he went to meter a 220 volt circuit and the thing exploded in his hand. It too was rated for 750 volts. He took it apart and found it was circuited wrong internally! One of the connections inside went straight to ground. BAM!

Worst I've ever had happen to me was I blew a fuse in a meter one time, but it was totally my fault. For some dumb reason I had left the meter to mA instead of A (plus the lead). Total brain fart on my part, I'd been working on low voltage stuff all day and just didn't switch it and replug the lead. Zap!

I know another guy who got bit in a 480 panel when he dropped one of the probes and tried to catch it (bad plan!).

FCD, make sure the meters you use have true RMS on the AC side. You'll get erratic readings especially on 3 phase circuits on the AC side of the meter if they're not true RMS. I used a Fluke 376 at work. It has an AC/DC clamp on ammeter as well as a load of other settings that come in handy whether fixing a 48 VDC lift truck or troubleshooting diodes on a circuit board to 480 VAC distribution panels. It would work well with GenSet troubleshooting.
I own an old Fluke 77 and a newer 177. Both still work and both are very accurate. Both are true RMS, also.

The newest multimeter I bought is a piece of junk, and it is already maybe twelve years old and it looks like new because I grab the old meter with the needle gauge on it all the time because it is accurate. The new meter gives inconsistant results. Sometimes it is right but it can vary a lot from one probe to another. I need to go out and buy a good old fashioned meter from somewhere, if the leads were not messed up, I would never have bought a new expensive one.

It isn't hard to figure out why the new meters are junk, the old one I have cost ninety bucks and the new improved one cost thirty eight or thirty nine bucks. But I wanted to buy the same brand and type of meter as I had before and they were the same as the new one I bought and the same price from the wholesale electrical parts store where I have had an account for thirty years, being I had a master electrician working for me and I was working on my journeymans license, I was able to get an account there for my business, which was really handy to have. I also have an account at a furnace and heating wholesale place, where I can get just about anything furnace related with my account other than the furnaces themselves because of agreements with furnace contractors in the area. I still know a couple of furnace contractors so I can buy a furnace from one of them at their cost...Oh wait, only one now, the other guy retired last year.

If you find a good and reliable multimeter FCD, let me know what the brand and model number is so I don't have to go through all of the bs trying to find one myself. I like learning from others misfortunes if possible.

originally posted by: Flyingclaydisk






My old meter was taking low readings. Automotive oil had soaked into the insulation of one of the probe wires

If it hasn’t been mentioned try checking the probe wire conductivity.

T5-^00 simple and cheap for everyday use then A 28 for more detailed stuff.

That's what's in my bag.

Cant go wrong with a Fluke 789.

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