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Klein Tools

Klein Tools ET350

Klein Tools ET350 4-in-1 circuit breaker finder, receiver and docked transmitter, front view on a white background

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Klein Tools ET350

Type:
Electronic tester; circuit breaker finder with outlet diagnostics, GFCI test, non-contact voltage detection and work light
Operating voltage:
85 to 135V AC, 50/60Hz; GFCI test 102 to 135V AC (instruction manual)
Designed for:
120V AC electrical systems, indoor use only

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Package details

Model: ET350

Condition:
Confirm new or reconditioned on the listing
Quantity:
Confirm package quantity on the listing
Included essentials:
Transmitter, receiver, case, batteries

Important limit: Strictly a 120V AC tester: Klein forbids connecting it to higher-voltage supplies, and it is indoor-only

Confirm condition, quantity and included accessories on the retailer’s listing.

Specifications checked November 5, 2026. Full product details

Size and package

Size and placement

Size (transmitter docked in receiver)
12 x 2 x 1.36 in (305 x 51 x 35 mm)
Weight
7.2 oz (204 g) with transmitter, receiver and batteries

In the box

Transmitter, receiver, case, batteries

Manufacturer specifications

Klein Tools ET350 4-in-1 Digital Circuit Breaker Finder

A plug-in digital circuit breaker finder that also diagnoses outlet wiring, tests GFCI devices, detects voltage without contact and carries a built-in LED work light.

Why people pick it

  • Four tools in one: breaker finder, outlet wiring diagnostics, GFCI test and non-contact voltage detection, per Klein's page
  • Shows the wiring condition on an LCD and flags out-of-range voltage (30-85V or 135-150V AC) with a red indicator
  • GFCI test reports the time to trip, per the manual
  • Rated for a 2 m drop and IP40, with a transmitter that docks inside the receiver for storage

Know before you buy

  • Strictly a 120V AC tester: Klein forbids connecting it to higher-voltage supplies, and it is indoor-only
  • Klein states it will not indicate ground quality, two hot wires, multiple combined wiring faults, or reversed ground and neutral
  • Batteries (4 x AAA) power the receiver and transmitter, unlike self-powered outlet testers

Full specifications

TypeElectronic tester; circuit breaker finder with outlet diagnostics, GFCI test, non-contact voltage detection and work light
Operating voltage85 to 135V AC, 50/60Hz; GFCI test 102 to 135V AC (instruction manual)
Designed for120V AC electrical systems, indoor use only
Breaker findingLearn and Locate modes: scan the panel in Learn Mode, then in Locate Mode to find the correct breaker; visual and audible indication
Outlet diagnosticsDetects open ground, open neutral, open hot, dual open (neutral and ground), reversed hot/ground, reversed hot/neutral; red indicator flags low (30-85V AC) or high (135-150V AC) detected voltage
GFCI testCreates a 6 to 9mA ground fault and shows time to trip; not designed for 30mA ground-fault devices
Non-contact voltageBlinking or steady LED in the tip plus audible beeps when voltage is present
Auto power offReceiver and transmitter after 3 minutes of inactivity (disabled on the transmitter when connected to a live outlet)
Batteries4 x AAA alkaline (transmitter and receiver, 2 each, included)
Drop protection6.5 ft (2 m)
Ingress protectionIP40 dust resistant
Size (transmitter docked in receiver)12 x 2 x 1.36 in (305 x 51 x 35 mm)
Weight7.2 oz (204 g) with transmitter, receiver and batteries
StandardsConforms to UL STD 1436; certified to CSA STD C22.2 No. 160
IncludedTransmitter, receiver, case, batteries

From manufacturer documentation, checked November 5, 2026. Spotted an error? Tell us.

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