Extech 380580 Battery-Powered Milliohm Meter, Four-Terminal

Extech 380580 battery-powered milliohm meter for field use

The Extech 380580 is a portable four-terminal milliohm meter that runs on eight AA batteries, so it can be carried around a plant or substation and used where no mains outlet is available. It measures from 0.1 mΩ resolution on its lowest range up to 2000 Ω, shows the result on a 2000-count LCD, and is supplied in a water-resistant case with a shoulder strap and two different test-lead sets.

Protection against over-temperature and over-voltage, invalid-test indicators that stop a wrong connection from producing a misleading number, and an auto-hold function make the 380580 forgiving for technicians who use it only occasionally.

Technical specifications of the 380580

The figures above come from the 380580 datasheet.

How the 380580 avoids measurement errors

Low-resistance readings are easy to get wrong because of poor contact. The 380580 injects the test current through one pair of terminals and measures the voltage across the part through the other pair, which removes lead and clip resistance from the result. If a clip is not making proper contact, or if the circuit is live, the invalid-test indicators warn the operator rather than displaying a number that looks plausible.

The two lead sets serve different jobs. The set with four alligator clips suits larger conductors and bolted joints where a clip can grip the metal. The set with two Kelvin alligator clips allows a four-wire connection with just two clamps, which is quicker on cable lugs and bus joints with limited access. The over-temperature protection safeguards the instrument if the test current runs for long periods on a very low resistance.

Typical field jobs for the 380580

• Joint resistance checks on busbar bolts and links during switchgear maintenance.
• Bonding and earthing continuity of pipework, vessels and cable trays.
• Contact resistance trending on breakers and isolators across shutdowns.
• Resistance of cable conductors and lug terminations after installation.
• Winding resistance of small motors and heaters on the 20 Ω and 200 Ω ranges.

If a 10 A test current or resolution down to 1 µΩ is needed, look at the Extech UM200; if a bench-top comparator is needed for sorting, look at the 380562. The 380580 remains the practical choice for general site work.

Selection checklist for the 380580

• Confirm that the resistances you measure lie between 0.1 mΩ and 2000 Ω.
• Confirm that a 100 mA maximum test current is acceptable for the object under test.
• Check that eight AA batteries are available; the instrument ships with a set.
• Decide whether spare Kelvin lead sets (380565) are required.
• Decide whether NIST-traceable calibration (the 380580-NIST version) is required.

Operation and maintenance of the 380580

Install the batteries, connect the chosen lead set, select the range and clip onto the part with the voltage clips inside the current clips. Ensure the circuit is de-energized and discharged first. Use auto-hold to freeze the reading when the display is awkward to view. The 380580 switches itself off after a period of inactivity, which preserves battery life.

Keep the clip jaws clean, wipe the case with a damp cloth, and store the instrument with the lid closed. Replace all eight batteries at the same time and remove them if the meter will not be used for months. Calibration is best handled through a qualified laboratory at the interval set by your quality system.

Applications of the 380580 in Oman and the GCC

Maintenance teams in power stations, substations, oil and gas facilities and desalination plants use battery milliohm meters on routine rounds, since many measuring points are far from sockets. The water-resistant case and strap help in dusty, hot environments, and the instrument can be used on outdoor switchyards and on platforms. In hot weather, let the instrument settle in shade before taking critical readings, and always record the ambient temperature next to the measurement for later comparison.

Information to send with an RFQ for the 380580

• Part number 380580 and the required quantity
• Resistance range and type of joint, contact or conductor under test
• Spare lead sets (380565) or NIST-traceable calibration if required
• Delivery location in Oman or the GCC and the required lead time
• Whether calibration documentation or a traceable calibration certificate is required

Storage, handling and spares for the Extech 380580

Store the Extech 380580 in its case or holster with the test leads disconnected. Remove the batteries if the meter will not be used for several weeks, because leaking cells can damage the battery contacts. In Oman and the GCC, do not leave the instrument in a parked vehicle during summer, where cabin temperature can go well above the storage limit in the user manual.

• Inspect test leads, probes and clamps before each use and replace any lead with damaged insulation or exposed metal.
• Use only leads and accessories rated for the same or a higher measurement category than the work you do.
• Keep spare fuses of the exact type given in the manual; a wrong fuse removes the protection the meter is built with.
• Plan a regular calibration interval, often twelve months, and keep the certificate with the instrument records.

If your team uses several units of the Extech 380580, it is useful to order spare test leads and batteries in the same RFQ, so that a meter is not taken out of service for a simple accessory.

Documents and quotation

A datasheet for the Extech 380580 is attached on this page. It lists the ranges, resolution and accuracy for the model.

Send us the part number 380580, the quantity and the delivery location in Oman or the GCC, and we will reply with availability and a quotation. Seven Star LLC is an independent supplier in Muscat and is not affiliated with the manufacturer.