Stray voltage
- Thread starter Mike7744
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I think your oversimplifying the results displayed. What if it's over 1 volt and how did you arrive at that number? I agree the least significant digit of the meter is not important for this measurement but does serve a useful purpose when making other measurements. The problem is that meters are inexpensive but very few truly understand how to use them properly and how to interpret what they are reading. And the OP checked for AC leakage, what about DC?
How did I arrive at that number? I watched the video. Could be DC voltage, but I'm not going to comment on that as he didn't show us any testing of DC voltage.
The amount of times people think it's stray voltage vs the number of times where it is is nearly infinite.
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A lot to unpack here, but will try to keep it simple. You don’t “ignore” the last digit of a multimeter, you need to understand the range and accuracy and resolution specified. The last digit may be +/- 1 or some other specification, and may differ depending on scale.
0.3 Volts should not just be assumed to be 0 volts, for example. You need to read the stated accuracy to determine what it means. It could be 0 or it could be 0.2 or 0.3 or as high as 0.6
As for “stray voltage” unless you are reading 90 VAC or above, the voltage is likely induced and not a fault.
But, most people really should not be using a digital voltmeter to test for “stray voltage” in the first place. Voltage readings in this context are almost meaningless without a current reading.
Do yourself a favor and protect yourself by using GFCIs on all aquarium equipment. You don’t need a meter, if the GFCI trips, you have a fault.
0.3 Volts should not just be assumed to be 0 volts, for example. You need to read the stated accuracy to determine what it means. It could be 0 or it could be 0.2 or 0.3 or as high as 0.6
As for “stray voltage” unless you are reading 90 VAC or above, the voltage is likely induced and not a fault.
But, most people really should not be using a digital voltmeter to test for “stray voltage” in the first place. Voltage readings in this context are almost meaningless without a current reading.
Do yourself a favor and protect yourself by using GFCIs on all aquarium equipment. You don’t need a meter, if the GFCI trips, you have a fault.
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I worked in the Electronics Industry for a large Defense Contractor for 40 plus years and used every kind of Meter you can think of. Multimeters, Milliohm meters, Meggers, Hi-pot Testers, Kelvin 4 wire, Clamp Ammeters, HV Probes, etc. and what Bean is saying is spot on. There simply is no consistent universal measurement spec that can be used in this case.
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I crank the old megger up once in a while and zap myself just to see if it still works…. No hipots here, but some scary tube amps that I poke around in once in a while. Looking to build some monoblocks with 866a rectifiers and pretty blue mercury glow in the near future.
I never worked on Tubes during my career, plenty of HV Power supplies though. All of the Items we Manufactured had transitioned to the "State of the Art" at the time. Transistors and Integrated Circuits.
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Current amps I am working on are only 450-500V (VTA-120) but some designs can go to 5kV or higher. EL34s and similar are often 800V or higher plate (B+) voltages. Kinda of crazy no matter what. The one hand in the pocket rule is always important when poking around in these things.I never worked on Tubes during my career, plenty of HV Power supplies though. All of the Items we Manufactured had transitioned to the "State of the Art" at the time. Transistors and Integrated Circuits.
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