Extech EX840A 1000 A True RMS AC/DC Clamp Meter with IR

Extech EX840A 1000 A true RMS AC/DC clamp meter with IR thermometer

The Extech EX840A is a CAT IV 600 V clamp meter with a 43 mm (1.7 in) jaw that measures true RMS AC and DC current up to 1000 A, adds a built-in non-contact infrared thermometer with a laser pointer, and includes LoZ mode, a low-pass filter, peak hold and an inrush function. The IR thermometer reads -50 to 270 °C at an 8:1 distance-to-spot ratio, so an engineer can scan motors, terminals and bearings for hot spots without touching them.

The EX840A is the AC/DC version of the EX8xxA series; the EX820A is AC only. A 6000-count backlit display, an ergonomic double-molded housing for one-hand use, an 8-piece industrial test lead kit, a Type K bead-wire probe and a 9 V battery come in the kit.

Technical specifications of the EX840A

The figures above come from the EX8xxA series datasheet.

How the EX840A finds electrical problems faster

Heat is the earliest visible sign of a loose termination, an overloaded phase or a failing bearing. With the IR thermometer, the technician points the EX840A at a lug, a contactor pole or a motor end shield and sees the surface temperature without contact; the laser pointer marks the spot being measured. Because the spot size grows with distance (8:1 ratio), the instrument must be close enough for the target to fill the spot.

Combined with the 1000 A current range and the inrush function, the same instrument shows whether a hot terminal is carrying more current than expected, and captures the start-up current of a motor, which is often the cause of terminal heating in the first place. The low-impedance mode avoids ghost-voltage misreadings when checking isolation.

Where the EX840A fits among Extech clamp meters

The EX840A is the top 1000 A clamp with IR: for a lighter 400 A clamp see the MA443 series; for the highest current and 40,000 counts see the MA1500; for power measurement see the 380976-K. Choose the EX840A when DC current, high current and temperature scanning belong in the same instrument.

• Switchgear and MCC thermal checks with current in the same visit.
• Battery and DC supply current checks up to 1000 A.
• Motor start-up current with the inrush feature.
• Noisy drive outputs with the low-pass filter.

Selection checklist for the EX840A

• Confirm the maximum current is within 1000 A and the cable fits a 43 mm jaw.
• Decide whether DC current is required (EX840A) or AC only (EX820A).
• Check the IR spot ratio of 8:1 against the distance you will measure from.
• Confirm that CAT IV 600 V meets the installation category.
• Decide whether the NIST-calibrated version is required.

Safety and care of the EX840A

Never point the laser at eyes. Use the supplied leads for voltage measurements, keep fingers behind the guards, and remove the leads when measuring current with the jaw. IR readings depend on surface emissivity, so shiny metal reads low; use a patch of tape or paint on the target for comparison. Keep the lens clean, replace the 9 V battery when the indicator shows and store the EX840A in its case.

Applications of the EX840A in Oman and the GCC

In hot climates, loose terminations in switchrooms heat up faster, so a quick IR scan with a current reading is a practical routine for electrical maintenance in power plants, oil and gas facilities, desalination plants and commercial buildings. The laser pointer and the clear display make it simple to log temperature and current during preventive maintenance rounds.

Getting good IR readings with the EX840A

Infrared thermometers measure the radiation from a surface, and the result depends on how well that surface radiates. Painted or oxidized surfaces and electrical insulation read close to their true temperature, while bare copper and polished aluminium read low because they reflect their surroundings. For a fair comparison, scan three identical connections under the same load and compare them with each other instead of relying on absolute numbers; a lug that is clearly hotter than its neighbours is the one to inspect. Stay within a distance where the target fills the 8:1 spot, and record the load current beside each temperature so that the finding can be judged.

Take the readings with the equipment under normal load, since a connection that is fine at 20% load can run hot at full load, and repeat the scan after any repair to confirm the improvement.

Information to send with an RFQ for the EX840A

• Part number EX840A and the required quantity
• Maximum current and cable size
• Whether the EX820A (AC only) or the NIST version is preferred
• Delivery location in Oman or the GCC and the required lead time
• Whether calibration documentation or a traceable calibration certificate is required

Documents and quotation

A datasheet for the Extech EX840A is attached on this page. It covers the EX820A and EX840A models.

Send us the part number EX840A, 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.