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[Peter Kowalczyk]

I'm looking to get a DVM + current probe for on-site use.  My goal is to measure my real world current draw to better balance and distrubute loads across the few circuits that may be available in smaller rooms, as well as recepticle voltage confirmation.  The combo clamp / DVM types look like the right tool.   Any particular units you'd recommend?  other approaches better?

thanks!

[Stephen Swaffer]

I have been partial to Fluke meters for years, but the Klein CL series of clamp meters offers a lot of bang for the buck.  I have a CL2000.  Not only do you get a DVM and clamp current probe, but also a built in NCVT.

[Jonathan Johnson]

I'm looking to get a DVM + current probe for on-site use.  My goal is to measure my real world current draw to better balance and distrubute loads across the few circuits that may be available in smaller rooms, as well as recepticle voltage confirmation.  The combo clamp / DVM types look like the right tool.   Any particular units you'd recommend?  other approaches better?

Note that you cannot just clamp a meter around a typical line cord and get a reading -- the opposing current in the two supply conductors (hot-neutral) cancel each other out. You have to be able to put the meter around the individual conductors. Usually, this requires either accessing the inside of a panel, or interrupting the circuit to insert a metering loop such as the Extech AC Line Splitter.

You don't want to unplug your power amp in the middle of a set just to see what the current draw is -- you have to plan ahead, and if you have only one metering loop/line splitter, it will take a very long time to get a set of readings from each device.

[Mike Sokol]

You don't want to unplug your power amp in the middle of a set just to see what the current draw is -- you have to plan ahead, and if you have only one metering loop/line splitter, it will take a very long time to get a set of readings from each device.

If you're on camlocks, it's really simple. Just clamp around each cable and you can easily find how well the system is balanced. However, it sounds like you're inside on Edison outlets trying get as much as possible out of each 20-amp circuit without tripping the breaker. I've got one of these Kill-A-Watt type meters in my demonstration kit, but I've never tried them on an amplifier. Might be worth a $15 per outlet experiment to give it a try for monitoring receptacle amperage in small venues.

[Peter Kowalczyk]

Note that you cannot just clamp a meter around a typical line cord and get a reading -- the opposing current in the two supply conductors (hot-neutral) cancel each other out.

Thanks Jonathan; my ignorance is showing.  That makes perfect sense, of course, so glad I asked!  (Pretty comfortable with the venerable Fluke 87 in a Lab setting, but I've not had the opportunity to use a clamp meter yet...) 

Mike - yes, mostly indoors on edisons.  The rig is all self-powered Class-D Speakers and LED lights.  I've yet to trip a breaker in the room I've been working lately, but I'd love to get a better idea how much power 'headroom' I've got.

What would you bring as power test equipment to a small (<250 ppl / 1500 square-foot) indoor gig?  Short of flipping breakers while a buddy watches a cube outlet tester / lamp / etc., do you have a procedure for determining what receptacles are on different circuits?

thx...

[Stephen Kirby]

I have a device called a Killawatt that looks similar to the thing Mike posted.  I has modes for line voltage (so you can watch for gross voltage drop), amps and watts.  I also have one of the Extech splitters and a Fluke clamp meter which is more accurate.  The Extech has a X10 loop for lower current measurements where the clamp drifts around.  The clamp also works when I'm using the tail adapter for my CA distro where I've cut back the jacket so I can hook it to a disconnect, range plug or whatever.

[Mike Sokol]

What would you bring as power test equipment to a small (<250 ppl / 1500 square-foot) indoor gig?  Short of flipping breakers while a buddy watches a cube outlet tester / lamp / etc., do you have a procedure for determining what receptacles are on different circuits?

I've got one of these in my road kit. You have to understand how to calibrate it for each panel, so read the directions. But it works pretty well most of the time.

[Jonathan Johnson]

I've got one of these in my road kit. You have to understand how to calibrate it for each panel, so read the directions. But it works pretty well most of the time.

Klein markets the exact same thing, in orange. Available from Home Depot.

It's useful for helping to identify a breaker, but it is not accurate enough for the results to be considered reliable. The circuit in question should be verified by other means. The plug-in module does have an indicator lamp, so when you turn off the breaker you can verify that the lamp goes out. Using a voltmeter to verify that a circuit is de-energized is ALWAYS a good idea.

[Peter Kowalczyk]

Thanks for your input, folks.  I purchased two Extech Line Splitters and a Fluke 323 clamp meter (also partial to Fluke, though I've always thought the name is ironic for a test equip. mfg!) and did a bit of testing during last night's show.

I placed the two line-splitters on one side of the PA - one for the sub (Meyer 700-HP) and one for the top (Meyer CQ-1). I didn't record my measurements, but I was surprised to see that even with the band rocking full-tilt boogie, current draw wasn't even twice the idle current.  Combined, one side of the PA was <3A burst max (at least during my short measurement session), which makes me feel a bit better about placing them both on a single 120V / 20A circuit.  Bigger band onstage tonight, and I've got an assistant who can help free up some of my time to get some more detailed measurements... 

[TJ (Tom) Cornish]

Thanks for your input, folks.  I purchased two Extech Line Splitters and a Fluke 323 clamp meter (also partial to Fluke, though I've always thought the name is ironic for a test equip. mfg!) and did a bit of testing during last night's show.

I placed the two line-splitters on one side of the PA - one for the sub (Meyer 700-HP) and one for the top (Meyer CQ-1). I didn't record my measurements, but I was surprised to see that even with the band rocking full-tilt boogie, current draw wasn't even twice the idle current.  Combined, one side of the PA was <3A burst max (at least during my short measurement session), which makes me feel a bit better about placing them both on a single 120V / 20A circuit.  Bigger band onstage tonight, and I've got an assistant who can help free up some of my time to get some more detailed measurements...

Yes, audio can end up being surprisingly power efficient.  Beware current transients though - depending on the speed of your meter, you may be missing some of the peak draw of things like kick hits.  The peak hits may be short enough in duration to not significantly contribute towards breaker heating and may be integrated to some degree by your tester anyway, but you'll still want to leave a little headroom.

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