Klein Tools RT250 GFCI Outlet Tester with LCD Display, Electric Voltage Tester for Standard 3-Wire 120V Electrical Receptacles,Green/Red

Klein Tools RT250 GFCI Outlet Tester with LCD Display, Electric Voltage Tester for Standard 3-Wire 120V Electrical Receptacles,Green/Red

Q: Is it ok to use this tester for the 20a power outlet (not gfci)?

A Very good question, since the device name starts with GFCI. Answer is YES, because despite the name, the device is mainly a regular outlet tester, checking cross wiring, missing wiring, and reporting voltages, all worthwhile tests for non-GFCI outlet. Also works with 15amp & 30amp with adapter. Thanks for the question.

Q: Most of the outlets in the basement where i'm living say >6.00 when i test them. are they wired wrong? is it safe to use the outlets?

It is not safe to use those outlets. If an outlet is good, the green light on the tester should illuminate, and the display should register a voltage close to 120 volts.

Q: Is this accurate enough to measure with some confidence which is the most upstream receptacle in a circuit for choosing gfci location?

Resolution accuracy inadequate for that task. Displayed digits determines resolution. In this case, meter accuracy will not be and can not be better than +/- 1 volt because digital resolution is always +/- 1 in the least significant digit. Example: If measuring a true, standardised 120 volts, meter might display 119V (-1), 120V or 121V (+1) if calibrated/adjusted correctly. You've got the right idea, but this meter displays only 2-1/2 digits (120V). You will need a meter with 3-1/2 (120.0V) digits displayed. Worst case resolution at 120 volts will then be ~0.1V (100 mV). You need to see those millivolts differences. Get one with stated accuracy and preferably calibrated. Cheers!

Q: What will happen if you press the gfci test on a non gfci? will it do nothing. or will it trip the breaker in the panel, and i have to flip the switch

The amber lights on the tester will blink, nothing will trip.

Product ID: 557085750

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Details

Brand
KLEIN TOOLS
Power Source
Corded
Style
Receptacle
Colour
Multi
Item Weight
0.26 Pounds

📊Clear LCD readout

⏱️Precise GFCI trip time

🛠️Patent-pending fault detection

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Description

⚡ Test smarter, work safer — the pro’s choice for flawless wiring!

VISUAL CONFIDENCE - Bright green/red LEDs give you immediate wiring status at a glance.
SPEEDY SAFETY CHECK - Trip time display lets you troubleshoot GFCI devices with professional precision.
HANDS FREE CONVENIENCE - Auto-Hold feature locks readings for those hard-to-reach outlets—work smarter, not harder.
INSTANT VOLTAGE CLARITY - Large backlit LCD ensures you never miss a detail, even in dim spaces.
NEXT LEVEL FAULT DETECTION - Patent-pending tech spots open neutral and ground faults others miss.

The Klein Tools RT250 is a professional-grade GFCI outlet tester designed for North American 120V 3-wire receptacles. Featuring a large backlit LCD, it provides clear voltage readings, identifies common wiring faults including open neutral and ground with patent-pending technology, and displays GFCI trip times for precise troubleshooting. Its Auto-Hold function and bright LED indicators enhance usability and safety, all backed by Klein’s 160+ years of trusted craftsmanship.

Specifications

Brand	KLEIN TOOLS
Power Source	Corded Electric
Style	Receptacle Tester
Colour	Multi
Item Weight	0.26 Pounds
Item dimensions L x W x H	11.5 x 2.9 x 5.1 Centimeters
Min. Operating Voltage	120 Volts
Specification Met	CSA
Upper Temperature Rating	60 Degrees Celsius
Measurement Type	Voltage Tester
Maximum Operating Voltage	120 Volts
UPC	092644693212
Manufacturer	Klein Tools
Global Trade Identification Number	00092644693212
Country of Origin	USA
Model number	RT250
Number of Memory Sticks	1
Special Feature	Large LCD Display; Patent Pending Detection of Open Neutral Open Ground Wiring Fault; Shows Amount of Time it Takes to Trip GFCI
Item Weight	118 g
Product Dimensions	11.51 x 2.95 x 5.08 cm; 117.93 g
Batteries	2 AAAA batteries required. (included)
Item model number	RT250
Item Height	2 Inches
Item Width	1.16 Inches
Included Components	2 x 1.5V AAA Alkaline Batteries and Manual
Are batteries included?	Yes

Have a Question? See What Others Asked

Is it ok to use this tester for the 20a power outlet (not gfci)?

Most of the outlets in the basement where i'm living say >6.00 when i test them. are they wired wrong? is it safe to use the outlets?

Is this accurate enough to measure with some confidence which is the most upstream receptacle in a circuit for choosing gfci location?

What will happen if you press the gfci test on a non gfci? will it do nothing. or will it trip the breaker in the panel, and i have to flip the switch

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