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Red handheld calibration box with terminal posts and range markings

ETCR

ETCR 3900 Lightning Protection Standard Resistance 0.001O~100KO electrician tool

SKU CH-J28Q-NXEXE MPN 3900

Lightning-protection standard resistance box covering 0.001 to 100 kΩ for calibrating ground-resistance and equipotential testers using four-wire connection

  • Labor warranty1 Year
  • Product typeTest Equipment
  • Color and finishRed
  • Number of items1 pack
  • Sold asBox
  • Parts warranty3 Years
  • Calibrate grounding testers accurately using 4-wire method
  • Measure resistance from 0.001Ω to 100kΩ with one box
  • Military-grade wire-wound resistors deliver 0.05% accuracy
  • Nine precision resistors cover full calibration range instantly
  • Solid construction ensures stable performance during field tests

Lightning protection calibration resistance

The ETCR 3900 is a standard resistance box built for calibrating grounding resistance testers and equipotential testers. It covers a range of .001 to 100 kilo-ohms using nine military-grade wire-wound resistors. The unit uses a four-wire connection method so measurements can be shifted without changing test leads. It is intended for electrical engineers and lightning protection inspectors who need a stable reference.

Suited for calibration labs, not general testing

This tool serves technicians who must verify or adjust the accuracy of dedicated grounding and equipotential instruments. It does not measure unknown resistances, voltage or current, so electricians looking for a multifunction multimeter or a portable insulation tester should look elsewhere. The package excludes batteries and an English manual, which must be sourced separately.

Resistance range .001 to 100 kilo-ohms

The single specification that decides fit is the calibrated resistance span of .001 ohm to 100 kilo-ohms with a best accuracy of .05 percent. If your calibration procedure requires values outside this span or a different connection method, the 3900 will not meet the requirement.

How it compares

Measured against everything we stock in Electrical Trade Tools & Kits, at today’s prices. Recalculated every night.

Price $190.99
Pricier than about 77% of the 5,006 comparable items (median $95.99).

Specifications

Product
Brand nameETCR
Model name3900
Product typeTest Equipment
Color and finishRed
In the box
Number of items1 pack

Questions about this item

Will the internal wire-wound resistors need periodic recalibration or replacement?

The unit uses nine military-grade wire-wound resistors with 0.05% accuracy; no user-serviceable parts are listed, so any recalibration would require sending it to a qualified lab.

What is the highest resistance value the box can simulate before it stops being a valid reference?

The range tops out at 100 kO, so that is the upper limit for any calibration or verification task.

Does the instrument generate noticeable heat or fan noise during continuous calibration sessions?

It is a passive resistance decade box with no active cooling or power supply, so it produces no fan noise and negligible heat in normal use.

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