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⚡ Power up your safety game with precision testing!
The Klein Tools RT250 is a professional-grade GFCI outlet tester featuring a large backlit LCD that displays voltage, wiring faults, and GFCI trip times. Designed for standard 3-wire 120V outlets, it includes innovative open neutral and ground fault detection, an auto-hold function for convenience, and comes with batteries included. Trusted by pros and DIYers alike, it delivers fast, accurate, and easy-to-read diagnostics to ensure electrical safety and compliance.


















| ASIN | B08QW7K1JJ |
| Best Sellers Rank | #698 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #1 in Voltage Testers |
| Brand | KLEIN TOOLS |
| Brand Name | KLEIN TOOLS |
| Color | Multi |
| Customer Reviews | 4.8 out of 5 stars 11,461 Reviews |
| Global Trade Identification Number | 00092644693212 |
| Included Components | 2 x 1.5V AAA Alkaline Batteries and Manual |
| Item Dimensions | 4.53 x 1.16 x 2 inches |
| Item Type Name | Klein Tools RT250 GFCI Receptacle Tester with LCD Display, for Standard 3-Wire 120V Electrical Outlets |
| Item Weight | 4.16 ounces |
| Item dimensions L x W x H | 4.53 x 1.16 x 2 inches |
| Manufacturer | Klein Tools |
| Maximum Operating Voltage | 120 volts |
| Measurement Type | Voltmeter |
| Minimum Operating Voltage | 120 volts_of_alternating_current |
| Model | RT250 |
| Number of Items | 1 |
| Part Number | RT250 |
| Power Source | Corded Electric |
| Specification Met | CSA |
| Style | Receptacle Tester |
| Style Name | Receptacle Tester |
| UPC | 092644693212 |
| Unit Count | 1 Count |
| Upper Temperature Rating | 60 °C |
| Warranty Description | See Manufacturer Website |
D**N
Simple and easy to use yet Amazing precision!!!
I picked up the Klein Tools RT250 GFCI Outlet Tester to help check a few outlets around my house, and I’m honestly impressed. This thing is super straightforward, just plug it in, the lights pop on, and you instantly know what’s going on with the wiring. No guesswork, no complicated setup, just clear results. The display is bright and easy to read, and the built-in GFCI test button is a lifesaver when checking bathroom and kitchen outlets. It helped me identify a miswired outlet in an older part of my house that I never would’ve caught otherwise. For something at this price, it feels durable and professional like something an electrician would actually use. If you’re a homeowner, DIYer, or just want peace of mind about the electrical safety in your place, this is a solid buy. Fast, accurate, and super easy to use. Highly recommend!
S**N
A little more expensive than the simple testers but worth it
I have one of those 3 LED testers already, the ones with the 2 yellow and one red light... and has a legend on it so that you can tell what is what. Works great... only issue is that when I was working outdoors or in a brightly lit room, it wasn't so obvious which LED were lit. So I bought the Klein as it wasn't a bad price and had the built in GFCI too. My old set, I had a separate GFCI tester which also worked great but just meant I had 2 separate testers. I played with the Klein soon as I got it having installed the batteries (Klein supplied I might add!!!!). You need to hold the power button down a couple of seconds and then the LCD comes alive. I tried it in various outlets around the house and found it to be a really effective device. The unit has only 2 LED's and there's no mistaking when they light up, both bright... A green one which clearly means OK and a red one meaning a fault in the wiring has been detected. I already had a purpose made miswired test lead I used for verifying the fault detection capability. Works great. I also like that it provides a reading of the actual voltage detected. It's not just a passive device. I have only one minor concern... When I put this in my toolbox I'm worried about something resting on the power switch and running the batteries down, so for now, having already carefully cut around the edge of the packaging, I'm keeping it in the packaged plastic. Might be overkill and maybe I'll buy a protective case for it if I feel inclined but for now, perfectly happy with the device and definitely recommend over the typical passive receptacle testers, even though they may be half the price.
B**K
Clear, accurate, and incredibly helpful
This Klein Tools RT250 Outlet Tester is a significant step up from the basic three-light testers. The LCD display is bright and easy to read, giving you actual voltage numbers and clear text for any wiring faults. It takes all the guesswork out of troubleshooting, and the GFCI trip testing function works perfectly every time. It’s a rugged, well-built tool that feels like it will last for years. Highly recommend it for both professionals and home DIYers!
F**C
This item works well and gives you a good reading on a possible problem.
This is a great tool for testing a GFCI if you are having problems with one in your home. I found out that mine was bad using this tester.
T**N
Good
Works well
J**N
Essential Tool for Electricians and DIY Pros
As an electrician or serious DIY-er who cares about doing things right, this tester has quickly become one of my favorite go-to tools. The RT250 is packed with features and built to handle real-world job-site demands. What stands out: The large back-lit LCD display clearly shows voltage, wiring condition, and the time it takes a GFCI to trip—making testing thorough and faster. It automatically detects open neutral, open ground, and other common wiring faults—no more guesswork. The built-in GFCI test button trips the device and the timer measures how long it takes—great for verifying that the GFCI meets spec. Rugged build: rated for a 6.6-foot (2 m) drop and meets CAT II 135 V safety rating—solid for a busy job site. It’s compact and lightweight (just 4.8 oz) but feels tough—durable housing and robust plug make it practical for everyday use. My experience on the job: I’ve used this tester across new installs, upgrades, and troubleshooting older receptacles. It quickly flags incorrect wiring (open ground, reverse hot/neutral, etc.), and the extra info like voltage readout and trip time saves me from coming back later for retests. Switching between circuits is fast, the screen holds readings with Auto-Hold (perfect for hard-to-reach outlets), and the indicator LEDs still give quick visual cues when I want them. Final verdict: If you’re working with North American 3-wire 120 V outlets (especially ones with GFCI protection), this tester hits all the right notes: precision diagnostics, rugged build, and efficient troubleshooting. It’s built like a pro tool—and priced so that it’s worth having in your bag every day. I highly recommend it.
L**M
Easy to read and use for proper outlet installation
An excellent product that takes the guess work out of electrical outlet installation. The display is easy to read and lets you know definitively if you are wired correctly or not. The red and green lights are nice as well as the LED voltage readout. Very accurate and a good value. Also great for checking GFI circuits.
A**O
Great comprehensive outlet tester
This tester provides reliable information about outlet wiring status for normal and GFCI outlets. The display is clear and results are easy to interpret. The only drawbacks is that requires batteries to operate.
F**S
Handy Tool
This tester could save your life. Used in an RV with no issues - the tester showed all was well. Using the same tester in a house, it gave an indication of potential wiring issue, as the voltage showed 30VAC on first check and 123V on a subsequent check. It will also indicate ground issue, reverse polarity. Glad to have bought.
Á**O
Probador Eléctrico.
Probador muy bueno y excelente y exacto buena marca se los recomiendo muy bien como herramienta los vá a sacar de apuros.
E**J
Quality
Works perfectly, if only I could find we're I misplaced it.
P**A
Buen probador
Excelente herramienta para medir voltajes
J**Z
Buena compra
Muy fácil de utilizar, de gran utilidad para la lectura de tomas de corriente.
Trustpilot
3 weeks ago
1 day ago