volt meters

[sitelights]

Volt meters or, more specificly, multimeters have a number of functions. A meter can be used to quantify AC or DC voltage, ohms, battery condition, confirm continuity and measure resistance. In practice, the most useful information is AC voltage and the AC readout should have auto ranging and sufficient sensitivity to measure to 00.00v of a volt in the low voltage range. Continuity testing is helpful in checking a lamp that may or may not have failed and to find open circuits such as a cut or damaged cable or fixture lead wire or a bad connection.

The two volt meters on my desk are both from RadioShack (r). One is eight years old and one is one year old; they both work fine. The older meter is model 22-179A and it cost about $20.00 in 1995; the newer meter model 22-809 cost about $30.00 The 22-179A dimensions are 4 1/4" L, 2 1/4" W and 7/8" thick; it weighs about 4 ounces. It has a "clamshell" cover which opens almost flat and friction catch closure; the two small hinges are prone to damage (the hinge pins drop out). The probe lead wires (black and red) are about 18" to the tip of the probe. The probes and their lead wires store inside the lid. It is rated "max 400v" and has a four place digital LCD readout 5/8" X 1 3/8". Both units are battery powered: 2 X 1.5v DC L42 buttons or their cross-matched equivalents.

The newer 22-809 is 4 1/2" L, 3" W and 3/4" thick and weighs about 5 ounces. It has a "book" type cover and a double-acting full length "piano" hinge so it opens completely flat and has a catch so it snaps shut securely. the probes and lead wires are about 22" long total. It is rated "max 500v AC/DC". The LCD screen is 1" X 1 1/2 " and the numerals are 7/16" high rather than the smaller screen numeral size of 5/16". This unit has auto-off (after 15 minutes idle time) and an analog sweep indicator for speedometer-type readings below the digital readout on the same screen. Two small buttons: data hold and audible alert on/off are below the display.

I looked on-line and found multimeters for as low as $8.95 + shipping so the question is how little can you pay for convenience and reliability? The minimum features that I would recommend are: a digital readout with at least 5/16" high numerals of the type known as 3 1/2 i.e. it can read to 19.99v or 199.9v (the 1/2 numeral refers to the left numeral reading only a 1); auto-ranging means you don't have to switch between line and low voltage; auto off is a real battery saver for forgetful types like me; most multimeters have all the functions listed above but it was worth a few more dollars to me to get an audible continuity check (a wimpy beep) and data-hold which stores the last reading; it is also useful to have the leads store inside the lid or, as in the 22-809 in a compartment next to the selector switch and LCD.

I cross-check my meters occasionally and they are all within .05v of eachother; my original meter was bench checked by a friend and it was within .01 of the test equipment. Some will say that a tenth of a volt is sufficient but I like to know if the 11.8v is 11.81v or 11.89v.

Buy a meter and use it at minimum to record the input voltage (primary: anywhere from 115v to 125v depending on the electrical service to property) and the output voltage (secondary) at the transformer and the first and last lamp. Write these numbers on the job folder or with indelible pen inside the transformer cover for future reference or for the "next guy".

[sitelights]

While not exactly a volt meter, I couldn't resist quoting an article from the September 2002 "Lite Tips" published by and distributed to customers of California Landscape Lighting.

"The First of It's [sic] Kind We have a revolutionary new voltage meter designed for landscape lighting. The 'Volt-o-meter' is so simple to operate and read, virtually no training is required. Better yet, because there are no batteries involved, it's always ready to use. The Volt-o-meter is a small handheld tester just 3 inches long and less than 1 inch wide and tall. Two sharp prongs sit at the bottom and are used to penetrate the PVC jacket of low voltage cable. Three LED lights are found on the face that show the range of voltage at that point in the cable. If the yellow LED glows there is less than 10.8 volts and possible dim lights. If the red LED illuminates there is over 12.8 volts and expect reduced lamp life. Finally if the green LED is on the voltage is between 10.8 and 12.8 volts, indicating acceptable light output vs. lamp life conditions. With this $10.90 tester your crews can know exactly how a system will perform as they install it. Every contractor, every work truck should have one. For more information contact our sales staff."

Every sentence of this advertisement disguised as editorial copy cries out for satirical comment. I will hold my tongue except for stating that this is another "trained monkey" device like the Rockscapes LVR12-15s (the only items I ever bought from callite.com).

In another article in the same issue there is a piece announcing the LVLIA 2003 annual meeting and conference held in Key West, FL at the historic Wyndam Casa Marina Resort.

On LVLIA's web site they are announcing the 2004 meeting in Scottsdale AZ ("Lighting professionals cannot afford to miss this event.")...actually YOU cannot afford it at all. All you LVLIA members who can't afford these junkets may take some solace in knowing that your membership dues are being well used by the unelected but self-proclaimed officers of LVLIA who apparently do nothing but go to annual meetings at fancy resorts with your money. Worthless but expensive.

lvlia.com but watch out, their web site is so lame my G4 Mac crashes every time I browse their site.

[Johns930]

How is the output voltage of a 12 vdc transformer properly measured at the last light in the line? We have a similar problem as another post, where most of the lights are working, except for the last two. There appears to be voltage at the end, although I do not believe I was measuring correctly with my old Simpson.

[sitelights]

Consider that the last two lamps may be getting very low current and the glow of the filament is not detectable in strong light. Strip the ends of the wire at or beyond the last fixture and lightly strike the conductors together; if there is no spark there is no current.

When metering (and the current in a low voltage outdoor lighting system is AC voltage) the readout or needle may "hunt" resulting in spurious readings. It may sometimes be the milivolts generated by the human body that is being measured.

The post "contact" in the Cable, Wire & Connectors Forum will give the points of failure and their frequency in a low voltage lighting system. Zero current is simply a break in the cable between the transformer and the metering point.