VOM meters

(ask me how I know)

 

OK, I'll ask.  Although I don't work on 400Hz, I can add to my store of knowledge.  The device I use does not make electrical contact.

 

Mike, I consider myself to be very expensive test eqpt, especially if I'm trying GRJ's test, whicih includes a free hair curl.

 

What happens to a test meter on 400 Hz?

 

Nothing special happens to a meter on 400hz, however some meters don't measure accurately at higher frequencies.  Most meters have a specification for AC measurement frequency ranges, though the cheaper meters may not specify it.

Subliminal message for RJR, 'TRMS meter with non contact voltage detection...' Sorry for the added temptation, but I was looking at one of these the other day and it looked like a neat gadget that we should all have (). 

 

I sure don't want to ruin your free hair curl though. Go ahead and get that first, having to pay for one of those could be more than the cost of the meter?

 

Also, I don't know about the happenings with the 400HZ, but I can tell you what happens when the maintenance man adds some 277 fluorescent fixtures to an office and switches the neutral instead of the hot and you go to add a motion sensor relay (energy saving deal) using the light switch for the breaker because no one knows where the breaker is for that room.

 

It was a truly 'enlightening' experience, similar to GRJ's holding on to the electrical box with one hand and the wire with the other to verify voltage status on the circuit.  

 

We had done a couple hundred rooms prior to that one without a problem. I started using one of those thingies that Mike CT stuck in the receptacle on each and every single wire up there right after that for the rest of the building.

Comment of rtr12's post.  Commercial installations, it is very common to have 480/277 volt and 208/120 volt circuits  mixed in the same conduits/boxes.  You can not depend on color codes for identification.  Something beyond the hair on the back side of your fingers is a huge safety factor.  Those voltages, I listed above, are a "no fun" experience.   

When in business, I would get one or two wild/weird experiences per year of this type of insanity.  Hopefully all went home that evening.  There was, and still is, a reason for safety meetings on a regular basis.

All went home safe, no one was hurt, just surprised (or would that be 'shocked')?  

 

While there are a lot of really good maintenance people out there, there are also a lot of them that should not be working on certain things, as you probably know. It's amazing that more things don't go wrong, causing injuries or even fires with some of the stuff like this that gets done in commercial buildings by people that just don't know any better. That wasn't the first thing like that we ran across in 37 years. Luckily I retired soon after that, still all in one piece.

If you work on an electrical circuit, don't rely that the licensed electrician who installed it got it right. 

 

When my sons bought new homes, I checked them out.  In one, I found Line & load on a GFI outlet near kitchen sink was reversed, so that outlet itself wasn't protected.  Another son bought an old house.  His brothers and I gutted and remodeled the kitchen.  I went nuts trying to shut off a kitchen 20-amp circuit.  Thought I was losing my mind.  I'd shut the breaker that we though controlled it, and find the circuit still live.  Never could get it off.  Then found out the problem:  it was being fed from opposite ends by 2 20-amp breakers.

I have run into some motor starters on commercial equipment that had the double feed you describe in the control circuit. Last one before retiring was in a high school on a cooling tower fan. The wiring looked like a bird's nest. It's unbelievable how some of this stuff even works, let alone not burning down the building it's in. It isn't just residential this happens to.

 

 

I just wanted to add to this thread that test leads make all the difference.  I ordered a set of Probemaster silicone leads when I ordered my new meter, and it's amazing how much more flexible they are and way less prone to kinking and tangling compared to the PVC leads that are stock with bargain to mid meters.  For about $25 I got a set (8043S) with alligator clips, spade connectors, and sprung hooks.  US manufactured, too.

well John i retired from a nuclear power plant where i was a electronic tech, and they HAVE A ACTUAL CAL LAB ON THE SIGHT THAT KEEPS ALL THE fluke and other type of electronic test equipment and keep all functions very accurate as it is required buy the federal government to insure safe and accurate calibrations of all systems that the test equipment is used on and they very rarely found any electronic test equipment out of calibration!Fluke makes excellent products usually when something is broken or out of calibration it was due to  the equipment improper use which damaged the equipment!

Alan

Here's a link to good price for Multimeter similar to the mastech:

 

http://www.mcmelectronics.com/...;utm_campaign=DD1533

 

RJJB, do these come with test leads or do I buy separately?

From the ad copy...

 

• Includes test lead and thermocouple probe

Note the MCM meter does not say RMS, or at least I didn't see it. 

 

I guess that's one interpretation of the Code stating 2- 20amp  circuits for the kitchen

 

J White

 

I doubt it's true-RMS that would be a dynamite price if it were.