Extech Decade Boxes (380400/380405/380500)

Fits cal-lab and service-bench substitution work that needs a passive Extech decade box — resistance (380400: 1 to 11,111,110 Ω in 1 Ω steps), capacitance (380405), or inductance (380500) — not a powered calibrator.

Key advantages

Resistance decade (380400) — 1 to 11,111,110 Ω in 1 Ω steps across 7 decades; ±(1% of reading + 0.3 Ω) per Extech 380400 UM.
Family coverage — Same SKU family also includes 380405 capacitance and 380500 inductance decade boxes.
Passive output — No power supply; resistance between red/black binding posts; white post is case ground.
Resistor network — Precision resistor decades (0.3 W); internal resistance 0.3 Ω.
Bench form — Benchtop use; ambient 0 to 50 °C (32 to 122 °F), <80% RH; CE (DoC on OEM product page).

Typical applications

Manual resistance substitution on meter, bridge, and DMM check benches.
Teaching and service setups that need decade steps instead of a fixed decade resistor card.
Capacitance or inductance substitution when ordering 380405 or 380500 instead of 380400.
Passive load or reference paths where a battery-powered decade is not required.

Selection guide

Parameter — Resistance → 380400; capacitance → 380405 (100 pF–11.111 µF per model table); inductance → 380500. Confirm which box before RFQ.
Ω band — 380400 covers 1 Ω to 11,111,110 Ω in 1 Ω steps — confirm your lowest and highest setpoints sit in that span.
Accuracy class — Plan around ±(1% of reading + 0.3 Ω) and the 0.3 Ω internal resistance for low-Ω work.
Connections — Three binding posts (red/black resistance; white case ground); confirm lead style and ground need.
Environment — Benchtop only within 0–50 °C and <80% RH; not a field IP-rated calibrator.

Common mistakes

Ordering “Decade Boxes” without naming 380400 vs 380405 vs 380500 — R, C, and L are different instruments.
Treating 380400 as a powered resistance calibrator — it is a passive decade network.
Ignoring the 0.3 Ω internal resistance when setting low-ohm values.
Expecting a combined R/C/L single chassis — OEM lists separate 380400 / 380405 / 380500 models.

When to RFQ / what to tell us

Which model (380400 resistance / 380405 capacitance / 380500 inductance) and the Ω, F, or H band you need.
Accuracy expectation, lead/ground practice, and ambient limits for the bench.
Quantity, ship-to, and whether you need more than one decade type in the same order.

Request a Quote · Get selection help

Specs

Spec	Value
SKU	25033
Brand	Extech
Model	Decade Boxes (380400 / 380405 / 380500)
Product type	decade_box
Measuring range	380400 resistance: 1 to 11,111,110 Ω in 1 Ω steps (7 decades). Family also includes 380405 capacitance and 380500 inductance decade boxes
Accuracy	380400 ±(1% of reading + 0.3 Ω) per Extech 380400 UM
Output signal	Passive decade box; resistance between red/black binding posts
Supply voltage	Passive (no power supply)
Ambient temperature	0 to 50 °C (32 to 122 °F); <80% RH
Sensor / network	Precision resistor decade network (0.3 W resistors); internal resistance 0.3 Ω
Electrical connection	Three binding posts (red/black resistance; white case ground)
Mounting	Benchtop
Approvals	CE (DoC on OEM product page)
Notes	SKU is Extech Decade Boxes family; specs primarily from 380400 Resistance Decade Box OEM UM on flir.netx (combined 380400/380405/380500 DS not available via NetX API).

Documents

Extech 380400 user manual (PDF)

FAQ

Q: Is SKU 25033 one box or a family? A: Family listing — 380400 resistance, 380405 capacitance, and 380500 inductance. State the model code on the RFQ.

Q: Does 380400 need power? A: No — it is a passive resistor decade between the red/black posts; white is case ground.

Q: What should I send for a quote? A: Model (R/C/L), range band, quantity, ship-to. Compatible with systems using Extech decade boxes — we do not claim authorized-dealer status.