Industrial electrical systems carry enough energy to cause serious injury or death, and the tools used on them are chosen with that in mind. This article describes the main kinds of tools in general terms. It is not a how-to for working on energized equipment. Electrical work should be done only by trained, qualified people, following the employer’s procedures, the equipment manufacturer’s instructions and local regulations.
Why tool choice is a safety decision
Two tools that look similar can behave very differently under fault conditions. A meter that is not suited to the electrical environment, a damaged lead, or a screwdriver without proper insulation can turn a routine task into a hazard. For this reason, electrical tools are usually selected, inspected and sometimes tested more strictly than general mechanical tools.
Ratings are key. Test instruments are typically marked with a category rating and a maximum voltage, indicating where in an electrical system they are designed to be used. Using an instrument outside its rating is a well-known risk. Always match the instrument to the system and read the manufacturer’s instructions.
Electrical test tools
Electrical test tools are the instruments that let a qualified person see what a circuit is actually doing instead of assuming.
Digital multimeter. The all-round instrument. It measures voltage, resistance and often current, and many models check continuity. It is also used to confirm that a circuit is de-energized as part of a verification routine. Leads, probes and fuses are part of the safety system, so damaged leads should never be used.
Clamp meter. A clamp meter measures current by clamping around a conductor without breaking the circuit, which is useful for checking motor loads or looking for unbalanced phases. Many also measure voltage.
Non-contact voltage detector. A pen-style detector that signals the presence of voltage near a conductor. It is a quick screening tool, but it can give false readings and is not a substitute for proper testing with a rated meter and the site’s verification procedure.
Insulation resistance tester. Sometimes called a megohmmeter, this device applies a test voltage to check the condition of insulation in motors, cables and other equipment. It is used on de-energized, isolated equipment, and its use requires training because the test voltage itself can be hazardous.
Phase rotation and other specialist testers. A phase rotation indicator checks the sequence of three-phase supplies, which matters for motors that must turn in the correct direction. Other instruments, such as ground resistance testers and power quality analyzers, are specialist items. Power quality analyzers relate to topics like power quality problems and harmonics.
Thermal imaging camera. A thermal camera shows surface temperature differences and can help spot overheating connections or components during inspections. It is generally used as a screening tool, with findings followed up by qualified personnel.
Hand tools for electrical work
Electrical hand tools share the shapes of ordinary tools, with features specific to the work.
- Insulated screwdrivers, pliers and nut drivers. Tools marked and tested for electrical work have an insulating coating meant to reduce the chance of contact with live parts. The coating is a last line of defense, not permission to work on energized equipment. Inspect it for cracks, cuts and wear, and retire any damaged tool.
- Wire strippers and cutters. Used to prepare conductors. A tool sized to the conductor makes a clean cut without nicking the strands.
- Crimping tools. Terminals and lugs need the correct crimper and die for the connector type and wire size. A poor crimp is a common source of heat and failure, so manufacturer guidance on the right tool is important.
- Torque screwdrivers and wrenches. Many terminals and lugs have specified tightening values. Loose connections run hot, and over-tightened ones can be damaged. A calibrated torque tool helps meet the stated value.
- Cable cutters and benders. Larger conductors and conduit need purpose-made tools. Details depend on the cable and conduit types, as with industrial cables in a plant.
- Fish tapes and pulling equipment. For running conductors through conduit.
Personal protective equipment goes with the tools
Tools are only one half of the picture. Qualified workers also wear appropriate protection, such as rated gloves, eye and face protection and flame-resistant clothing, selected for the hazard that has been assessed. This ties into broader electrical safety equipment requirements. Details of arc flash clothing and ratings come from a site’s hazard assessment and applicable standards, not from a general article.
Habits that apply to every electrical tool
- Inspect before each use. Look for damaged insulation, cracked cases, worn leads and bent probes.
- Check the rating. The instrument’s category and voltage rating must match the application.
- Verify the meter. Many procedures call for checking a meter on a known source before and after testing, to make sure it is working.
- Follow lockout tagout. De-energizing and locking out equipment, then verifying it is dead, comes before hands-on work in nearly all cases. The details belong to your site’s written energy control program.
- Keep tools in good order. Store meters and leads carefully, replace fuses only with the correct type, and send instruments for periodic calibration according to the manufacturer and site policy.
- Do not improvise. A tool that is not designed for the job, or a repair to a damaged lead with tape, should not be used on electrical systems.
When a test is more than a meter reading
Test readings need interpretation. A qualified electrician or technician understands what a reading means in context, whether in a panel, a motor control center or a control cabinet. For example, the tests used in panel inspection testing follow documented procedures and acceptance values, rather than rules of thumb.
If you are new to the field, the sensible path is training and supervised experience, not buying a set of instruments and starting. The tools listed here are helpful to know about, but they are only as safe as the person using them and the procedure behind the work.