does this actually place a load on the circuit for for voltage drop?

It simulates a 12,15, and 20 amp load and displays the percentage drop, according to the operating instructions.

Will this indicate open neutral or open ground when circuit is not energized?

Way late on answer this. If you’re talking about (Klein Tools RT210 Outlet Tester) then no, it has to have power on the circuit as this is not battery powered to show the tester how it’s wired.

Does this simulate and test both serial and parallel arc fault conditions?

This tester plugs into an outlet on the circuit under test, so it seems to me that automatically makes it a parallel device. Therefore it can only simulate an arc fault such as might occur in a parallel device, i.e. what you normally plug into an outlet. (A typical faulty item being be a lamp with a frayed power cord.) I believe the tester would have to be wired into the circuit in series to simulate a serial arc fault. I don't know the nature of the tester's design but it may be that tripping an AFCI unit (an AFCI outlet, for instance) with a parallel fault simulation may also prove the AFCI's ability to respond to a serial arc fault, at least in part. Disclaimer: I'm not an electrician or EE so you may want to dig farther on this subject, but I believe I have the basics right.

Does this protect trip a gfci protected receptacle with an open ground?

No it will not. No tester will trip a GFCI with open ground. You have to use the button on the receptacle/breaker in that case. Make sure the outlet is labeled with "no equipment ground."

Klein Tools RT390 Circuit Analyzer with Large LCD, Identifies Wiring Faults, GFCI and AFCI Tester, Voltage Drop, Displays Trip Time, Orange

Klein Tools RT390 Circuit Analyzer with Large LCD, Identifies Wiring Faults, GFCI and AFCI Tester, Voltage Drop, Displays Trip Time, Orange

Product ID: 513814177

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Details

Brand
KLEIN TOOLS
Colour
Orange
Item weight
222 g
Power source
Battery
Style
Receptacle

⚡Tests AFCI & GFCI with trip time & current

📺Large color LCD for clear results

🔋Voltage drop measurement at 12A, 15A, 20A loads

Description

⚡ Power up your inspections with the RT390 — the ultimate circuit analyzer for pros who demand precision.

TRUSTED LEGACY - From a family-owned brand since 1857, engineered for pros who refuse to compromise on quality.
BUILT TO ENDURE - Rugged design and premium components ensure this tool stands up to daily jobsite demands.
CRYSTAL CLEAR DIAGNOSTICS - Large color LCD delivers instant, easy-to-read wiring fault results—no guesswork.
NEXT LEVEL SAFETY TESTING - Detects both AFCI and GFCI faults with precise trip time and current data to prevent electrical hazards.
LOAD ACCURATE VOLTAGE DROP - Measures voltage drop under real-world 12A, 15A, and 20A loads for professional-grade accuracy.

The Klein Tools RT390 Circuit Analyzer is a professional-grade electrical tester featuring a large color LCD for easy diagnostics, comprehensive AFCI and GFCI testing with trip time and current display, and voltage drop measurement at multiple load levels. Designed for North American 120V AC outlets, it offers rugged durability and advanced fault detection, making it an essential tool for electricians, inspectors, and serious DIYers committed to safety and accuracy.

Specifications

ASIN	B0BT87LJRL
Brand	KLEIN TOOLS
Colour	Orange
Customer Reviews	4.8 out of 5 stars 252 Reviews
Global Trade Identification Number	00092644693632
Included Components	3 x AAA Batteries, Instructions, and Pouch
Item Dimensions	18 x 6.9 x 3.8 centimetres
Item Type Name	Circuit Analyzer
Item Weight	0.49 Pounds
Item dimensions L x W x H	18 x 6.9 x 3.8 centimetres
Item weight	0.49 Pounds
Manufacturer	Klein Tools
Maximum Operating Voltage	120 Volts
Measurement Type	Voltmeter, Ammeter, Ohmmeter, Time-based
Minimum Operating Voltage	135 Volts (AC)
Model Number	RT390
Power Source	Battery Powered
Power source	Battery Powered
Specification Met	Cat Iii 135v, Afci, Gfci, Ul, Fcc
Style	Receptacle Tester w/Voltage Drop
Style Name	Receptacle Tester w/Voltage Drop
UPC	092644693632
Unit Count	1.0 Count
Upper Temperature Rating	55 Degrees Celsius

Reviews

M**T

Standalone best wiring integrity tester!

6.01.2026

E**A

Muy bueno pero las baterías que trae son basura

Lo único vamos del producto es que las baterías se dañan muy rápido, hablo que una semana después de ponerlas se vaciaron :( así que recomiendo quitarlas cada que no lo usen o ponerle desde el principio unas de buena calidad

4.08.2024

L**Y

A unique tool. Expensive

30.12.2024

A**R

Great product

31.03.2024

J**.

Great for checking receptacles for more than just correct wiring

2.06.2025

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