Reliable Solenoid Testers

The probe may not have been defective. There may have been corrosion on the wires. I would try the tester out on every electrical connection to make sure it is working properly.

The new tester I assume is a digital unit. They draw so little current that corrosion on the terminal can stop any current flow to give a reading. The test lamp will draw higher current and break down the resistance of the corrosion.

Digital meters are a bloody menace.

"They draw so little current.. " this would cause them to be less sensitive to corrosion.

On the contrary...low voltage and low current are called 'dry circuit' and corrosion certainly has an effect on the working of the device.....

_{dry circuit}

_{A relay circuit in which open-circuit voltages are very low and closed-circuit currents extremely small, so there is no arcing to roughen the contacts.}

What happened is you were in two different locations. Your tester worked some where else but not there. The loose coupling between your body and earth differed in the two locations. These "single pole" testers depend on your body's capacitance to ground for the voltage reference. Assuming this is a neon device, there will be a metallic cap in the end of the tester. When you encounter a suspicious null voltage indication you should touch the metal cap with your finger. This changes the reference from mostly capacitive to mostly resistive. If there is voltage there it will light. If you really want to be sure touch something that is metallic and grounded with your other hand. As a precaution I would short the conductors momentarily just to be sure. No sparks, no circuit breakers tripping all good. Yeh.... Even at the location where you registered voltage during your bewilderment, you would have seen the intensity of the neon lamp increase a bit if you touched the metallic cap. These testers are very reliable, safe and robust. You should still check them every time immediately before using them. A caveat here. These single pole testing devices only work if the voltage under test is referenced to ground. In a correctly implemented, most commonly configured, and most frequently encountered installation environment this is the case. Beware in electrical environments where isolation transformers are used. A UPS can also be configured to operate as an isolated supply, ditto for rotary converters. Portable generators (and incorrectly installed fixed plant), and inverters can also energize circuits with a non ground referenced voltage. So take care in environments where you find these. Trust nothing.

If you just want to know whether a wire or circuit is live or not, it's pretty hard to beat the non-contact testers like the Fluke VoltAlert™. There are several of these available at hardware and Home Improvement centers, for around $15-25. You simply turn them on and hold the tip near a wire, and if the wire is hot, it will illuminate and/or beep. The original ones worked on anything over around 90 Volts, while some of the newer ones are much more sensitive. Many have adjustable sensitivities, which can be an advantage or a disadvantage, depending on the circumstances... You MUST test them on a known hot circuit EVERY TIME you use them, to be safe. I won't work on power circuits without one!

They do NOT measure or respond to current, only to voltage, and many of them only work on AC. They do give some rough indication of the amount of voltage present if you notice the distance at which they first illuminate. Some of them will show the presence of 480VAC from a distance of several inches, while 120VAC will only indicate at considerably smaller distance.

And hold it out the window of your truck while passing under a 500,000 volt power transmission line, and they light up! -- JHF

I think test equipment is more of a personal preference. I have a clamp on amp meter/ multimeter. This not an endorsement, but Home Depot has a pretty nice Klein 600amp, CAT-III, clamp on multimeter for $49.95, with Auto/ manual ranging, measures 200 millivolt to 600 AC/DC volts, 2 to 600 AC amps, resistance 200Ω to 20MΩ.

Here's a link to the Instruction Manual. Hell, I just might buy one for a spare The only other thing I might mention is, when working on 220 volt, always check both hot legs to ground for voltage before working on the circuit. Be Safe

Another instance where you may find a false safe indication, even with two pole metering, is a triac or scr controlled dimmer circuit which will not turn "on" without a load. Beware.

Has its fuse blown?

Correct me if I am wrong but everyone here seems NOT to like the probe type.

After my experience with a false reading I can see why. Corrosion or some build up on the probes or wire itself can make a false reading.

I will look into a clamp on type and still keep my old man's 1960-ish Light Bulb tester for a confirmation.

No, I will not be dealing with 220.... just 120v.

No, the fuse was not burnt, It just would not register a live wire until I played with it awhile . It worked fine on standard outlet receptacles....just the exposed wires were the problem.

Thank you all.

nm

On the contrary! Most of my measurement is with probes. There is no direct way to measure resistance or capacitance in circuit without probes, and accurate measurement of most voltages requires two probes. BUT, when my safety depends on knowing whether there is voltage present or not with respect to my body, I use the VoltAlert™ type. I do like Fluke, but I'm using the term VoltAlert™ like Frigidaire™, since I don't know the correct generic name for this type of indicator. Note the term indicator; its NOT a meter!

The clamp-on part of those meters that have clamp-on probes is ONLY used for measuring AC current. A hot wire that is not currently providing any current, like the black wire (USA, correctly wired 120V) leading to a light switch currently in the off position, would indicate zero with a clamp meter. You must use regular probes, either instead of or in addition to the clamp, on that type of meter, to measure voltage.

The advantage of a clamp-on meter is that it can measure current in a single wire without disconnecting it. Notice the single wire; it MUST be a single wire, not a cable. In a section of cable, like a power cord, the magnetic fields of the same current flowing in opposite directions in two wires will cancel, and the clamp-on meter will always indicate near zero, no matter how large the current.

I just now noticed the title of the posts. What does all of this have to do with testing solenoids? Everything I've said still applies if indeed you do want to test a solenoid.

The clamp-on (amprobe) won't get into tight spaces like in a receptacle box.

Sounds like corrosion. Use alligator clips when testing wires. They cut through the corrosion, and you don't need to juggle two leads and a meter.

What is a switch outlet? Is it a switch or an outlet receptacle? If a receptacle, there will be voltage at the terminals. If a switch, the voltage will be in only one wire. It would have to be read between the wire and a ground. Possibly the switch has been wired wrong (switch in common wire insteat of the hot wire).

I use the Circuit-Alert by Gardner Bender because it has a self test function built into it. They are only about 14 dollars to buy. The Fluke model I had didn't have a self test function. Check the tester on a known live circuit to verify the tester is working and as a final precaution touch the suspect wire to ground before working with it. It's a good idea to always treat wires as if they are live and that way you too will stay alive.

Elroy

Good advice!

Does the self-test do anything more than verify that the battery and LED are good?

No, as far as I am aware it is an indication that the tester if functioning, but not that it is capable of detecting voltage. The check on a known live wire will answer that question.