Klein Tools ET40 Digital AC/DC...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$78.16
$22.94
Klein Tools ET40 Digital AC/DC Voltage Tester 12 to 240V AC, 1.5 to 24V DC

Klein Tools ET40 Digital AC/DC Voltage Tester 12 to 240V AC, 1.5 to 24V DC

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Model: ET40
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In Stock (leaves warehouse same day if ordered before 3pm ET)

$78.16
$22.94
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Digital AC/DC Voltage Tester 12 to 240V AC, 1.5 to 24V DC

  • Warnings

    • Usage of this tester in any way other than that specified by the manufacturer can impair safe operation, resulting in severe injury or death.
    • Read, understand, and follow all instructions, cautions and warnings attached to and/or packed with all test and measurement devices before each use.
    • Always adhere to local and national safety codes. Use personal protective equipment to prevent shock and arc blast injury where hazardous live conductors are exposed.
    • Never use the tester on a circuit with voltages that exceed the category based rating of this tester.
    • Before each use, verify tester operation by measuring a known voltage.

  • Features

    • CATIII 250V, Class 2, Double insulation
    • Indicates polarity when measuring DC voltages
    • Built to withstand a 9.8-Foot (3 m) drop
    • Ingress protection IP41 dust and water resistant
    • Powers off automatically after approximately 2 minutes of non-use to conserve battery life
    • Built-in test lead holders on sides of tester
    • Identifies and distinguishes between AC or DC voltage
    • Bright LEDs illuminate to indicate the type and level of voltage detected
    • Uses 2 x AAA batteries (included)
    • Voltage Tester for AC voltages from 12V to 240V AC at four useful levels aligned with commonly used residential voltages
    • Low battery indicator with easily accessible battery compartment
    • Tests DC voltages from 1.5V to greater than 17 to 24V at four useful levels aligned with commonly used DC voltages
    • Pocket clip secures tester to pocket for reliable everyday carrying
    • DC Polarity Indicators for DC Positive, DC Negative, and Both Illuminated for AC. Tests Low DC Voltage to 1.5V. Built in Test Lead Holders on Sides of Tester.


ET40 - spec sheet

Manufacturer Resources

Spec Sheet

Product Specs

Accessories:
5139C, 5139PAD
Batteries:
2 x AAA
Case Included:
No
Control Type:
ON/Off Switch for Power ON/OFF
Display:
Analog LED
Drop Protection:
9.8' (3 m)
Frequency:
50/60 Hz
Ingress Protection:
IP41
Integral Lead Storage:
Yes
Interchangeable Leads:
No
Item Depth:
5.2400 in
Item Height:
1.1100 in
Item Weight:
0.2680 lbs
Item Width:
1.5200 in
Lead Length:
9" (22.9 cm)
Overall Height:
1.52" (3.9 cm)
Overall Length:
5.24" (13.3 cm)
Overall Width:
1.11" (2.8 cm)
Pollution Degree:
2
Standards:
CATIII 250V, CE
Tests Continuity:
No
Department:
Electrical
Product Group:
Test & Measurement
Product Subgroup:
Voltage Testers
Product Material:
Plastic Housing, PCB with Electronic Components
Product Weight:
2.3 oz (66 g)
Product Type:
Contact Voltage Tester
Product Width:
1.52 in
Product Depth:
5.24 in
Product Height:
1.11 in

Klein Tools ET40 – Frequently Asked Questions

1) Can the Klein Tools ET40 voltage tester be used on 480V three-phase panels?
No. The ET40 reads AC from 12V to 240V and is rated CAT III 250V, so it has no business on a 480V system. Its four AC indication levels are set for common residential voltages. For anything above 240V or beyond a CAT III 250V rating, use a tester rated for that category and voltage.
2) Does the ET40 tester tell you whether a circuit is AC or DC, and which way the polarity runs?
It does both. The ET40 identifies and distinguishes AC from DC, and when reading DC it shows polarity: separate indicators for DC positive and DC negative, with both lit at once signalling AC. Useful for sorting out low-voltage control, thermostat, and door wiring where you cannot assume what you are on.
3) Will the ET40 pick up low DC voltage like a 1.5V battery or a 12V control circuit?
Yes. DC coverage runs from 1.5V up through a greater-than-17-to-24V level, in four steps aligned with common DC voltages, so a single cell at 1.5V registers and so does a 12V or 24V control or alarm circuit.
4) How long are the leads on the ET40, and can they be replaced?
The test leads measure 9 inches (22.9 cm) and are not interchangeable, so they cannot be swapped for longer ones or replaced separately. Nine inches is short by design for a pocket tester, which matters if you are reaching deep into a panel or across a J-box.
5) Is the ET40 rated for use in a commercial panel, and what safety category does it carry?
The ET40 carries a CAT III 250V rating with CE marking, Class 2 double insulation, and Pollution Degree 2. CAT III 250V covers distribution-level work up to 250V, which includes typical 120/240V residential and light commercial panels and branch circuits. Never put it on a circuit above that category rating, and verify it against a known live voltage before each use.
6) Is the Klein ET40 a digital readout tester or an indicator-light tester?
It is an LED indicator tester, not a numeric meter. The display is analog LED: bright LEDs light to show the type of voltage and which of four levels it falls in. If you need an exact numeric value, an actual multimeter is the right tool; the ET40 tells you live/dead, AC or DC, polarity, and roughly what level.
7) Does the ET40 test continuity?
No. Continuity testing is not a function of the ET40; it is strictly an AC/DC voltage indicator. For ringing out a run or checking a fuse with no power on it, you need a continuity tester or a multimeter.
8) How tough is the Klein ET40 for daily service truck use?
Built to survive a 9.8 foot (3 m) drop and rated IP41 for dust and water resistance, with a plastic housing. It also has a pocket clip and built-in lead holders on the sides so the leads are not loose in a bag. IP41 covers dripping water, not immersion or hose-down.
9) Does the Klein ET40 come with batteries, and what does it take?
Two AAA batteries run it and they are included. There is a low battery indicator and the compartment is easy to get to for a swap. It also shuts off on its own after about two minutes of non-use, which keeps a tester left in a pouch from draining.
10) Will the ET40 tester fit in a shirt pocket or a pouch on my tool belt?
It is pocket sized: 5.24 x 1.52 x 1.11 inches and 2.3 oz (66 g), with a pocket clip. No carrying case is supplied. Klein's 5139C zipper bag and 5139PAD padded bag are listed as accessories if you want it protected in a bag.
11) Does the ET40 work on 50 Hz systems as well as 60 Hz?
Yes, the rated frequency range is 50/60 Hz, so it reads on either standard AC supply.
12) Does the Klein ET40 have to be switched on, or is it always live?
There is an ON/OFF switch for power. You turn it on to test, and if you forget, it powers down automatically after roughly two minutes of non-use.
How fast can I get the Klein Tools ET40 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Klein Tools ET40 come with a warranty?
Absolutely. The Klein Tools ET40 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Klein Tools ET40?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Klein Tools ET40 from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
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