Electrical tools: names, pictures and what each one is used for

Know where the line is

This page is a reference for what the tools are, not a licence to rewire a house. In the UK, most fixed wiring work is notifiable under Part P of the Building Regulations, and in many countries it must be done or certified by a qualified electrician. Replacing a light fitting or a socket faceplate on an existing circuit is generally permitted; new circuits, consumer units and anything in a bathroom or kitchen zone generally is not.

The reason is not bureaucratic. Electricity does not give you the feedback other trades do. A badly cut mortise looks wrong immediately, whereas a loose terminal looks perfect and starts a fire eighteen months later. If you are unsure whether a job is yours to do, that uncertainty is the answer.

Proving dead is a procedure, not a tool

Every electrician learns this as a sequence, and the sequence matters more than the instrument. Isolate the circuit, lock it off so nobody can restore it, prove your voltage indicator works on a known live source or a proving unit, test the circuit, then prove the indicator still works afterwards.

That last step is the one people skip and the one that kills. A tester that failed silently between the first and second check would have told you a live circuit was dead, and you would have believed it.

A non contact pen is a hint, not a test

Useful for a quick indication, and it will happily read nothing on a live conductor behind foil backed board. Never use it as the proof that something is dead.

Use a two pole voltage indicator

Purpose built, with fixed leads and no range switch to be on the wrong setting. This is the instrument the procedure is written around.

Lock off, and keep the key

A lock off kit on the breaker with your own padlock. A note taped to the board is not isolation, because somebody will move it.

Prove the tester before and after

With a proving unit or a known live supply. Both times, every time.

What the ratings on the tools mean

Electrical tools carry markings that are easy to ignore and are the entire reason they cost more than the equivalent from a general toolbox.

VDE and 1000V mean tested insulation

Each tool is individually tested to a far higher voltage than it is rated for. An ordinary screwdriver with a plastic handle has been tested to nothing.

CAT ratings describe where a meter can be used

CAT II for appliances and socket circuits, CAT III for distribution boards and fixed installation, CAT IV for the supply intake. It describes the size of transient the meter can survive, and using an underrated meter at the intake is how they explode.

The rating is on the tool, not the box

Look for the double triangle mark and the voltage on the tool itself. Sets are sometimes advertised as insulated when only some pieces are.

Inspect insulation before use

A nick in a screwdriver's coating makes it an uninsulated screwdriver. Damaged tools get binned, not taped.

Fused leads on a meter

Test leads should be fused and CAT rated to match the meter. Cheap unfused leads are the weak point in an otherwise safe setup.

What to buy first, in order

Stage one: testing and isolation

A two pole voltage indicator and a proving unit, a lock off kit, a socket tester, and a multimeter rated at least CAT III. Then a set of VDE insulated screwdrivers. Buy the testing before the fitting tools, because that is what keeps the rest of the list survivable.

Stage two: cutting, stripping and terminating

VDE combination pliers, long nose pliers and side cutters. Cable cutters for anything thicker than flex. Wire strippers, a cable knife, and a crimping tool with a ratchet. A terminal screwdriver with a fine flat tip.

Stage three: installation and diagnosis

Cable rods and fish tape for pulling through voids. An SDS drill and hole saws for chasing and boxing. A clamp meter for measuring load without breaking a circuit. A conduit bender if you work in metal conduit.

Mistakes that cost money, or worse

Using a non contact pen as proof

It can miss a live conductor entirely depending on shielding, insulation and how you hold it. It indicates presence, it does not prove absence.

An uninsulated screwdriver near a board

One slip bridging a terminal to an earthed enclosure. This is the most common cause of arc flash injuries in domestic work.

Overtightening or undertightening terminals

Both cause heat. Undertightened arcs, overtightened crushes strands and thins the conductor. A torque screwdriver removes the guesswork on anything critical.

Nicking the conductor when stripping

A nicked strand breaks later, inside the insulation, where nothing will show it. Strip with a stripper set to the right gauge rather than a knife.

Cheap unfused test leads

The fuse in the lead is what stops a fault becoming an explosion at your hand. Saving money here defeats a properly rated meter.

Working live because it is quicker

It is quicker, right up until it is not. There is no domestic job that justifies it.

Looking after test gear

Check leads for damage every time

Flex cracks where it enters the probe. That is the point where a lead becomes a bare conductor in your hand.

Calibrate meters used for certification

Anything whose readings go on a certificate needs periodic calibration. A drifting insulation tester passes circuits it should fail.

Replace fuses with the correct type

A general purpose fuse in a meter is not a substitute for the specified high rupture capacity one, whatever fits physically.

Keep insulated tools out of the bottom of a bag

The insulation is the tool. Rattling loose against masonry bits is how it gets nicked.

Store batteries out of meters left unused

A leaked cell destroys the instrument it was protecting your life with.

Frequently asked questions

What electrical tools do I need to start?

Testing first: a two pole voltage indicator, a proving unit, a lock off kit and a socket tester, plus a multimeter rated CAT III or better. Then VDE insulated screwdrivers and pliers. Buy the testing kit before the fitting tools, because that is what makes the rest safe to use.

What does VDE mean on electrical tools?

It means each tool has been individually tested to withstand a high voltage, typically 10,000V, and is rated for working up to 1000V. An ordinary screwdriver with a plastic handle has been tested to nothing, whatever it looks like.

What do CAT ratings on a multimeter mean?

They describe where the meter can safely be used. CAT II is appliances and socket outlets, CAT III is distribution boards and fixed wiring, CAT IV is the supply intake. It reflects the size of voltage transient the meter can survive, which is why an underrated meter can fail violently.

Is a non contact voltage tester enough to prove a circuit is dead?

No, and this is the most dangerous misunderstanding in the trade. It indicates that voltage is probably present, but it can miss a live conductor depending on shielding and insulation. Proving dead needs a two pole voltage indicator and a proving unit, checked before and after.

What is a proving unit for?

It generates a known voltage so you can confirm your voltage indicator actually works, immediately before and immediately after testing a circuit. Without the second check, a tester that failed silently would have told you a live circuit was dead.

What is the difference between a multimeter and a clamp meter?

A multimeter measures voltage, resistance and continuity through its probes, and measuring current means breaking into the circuit. A clamp meter reads current by clamping around a conductor without disconnecting anything, which is why it is the diagnostic tool of choice for load problems.

Can I do my own electrical work?

Some of it. Replacing a faceplate or a light fitting on an existing circuit is generally permitted. New circuits, consumer unit work and anything in bathroom or kitchen zones is usually notifiable and in many places must be done or certified by a qualified electrician. If you are unsure, that uncertainty is your answer.

What is the best way to strip cable without damaging it?

Use an adjustable stripper set to the conductor size, or a proper cable knife for the outer sheath only. A nicked strand is the failure you cannot see, because it breaks later inside the insulation where nothing shows it.

Why do crimps need a ratchet tool?

A ratchet crimper will not release until it has applied the full specified pressure, so every crimp is identical and properly formed. Pliers style crimpers depend on how hard you squeeze, and an undercrimped joint heats up under load.

What is a fish tape used for?

Pulling cable through a wall cavity, conduit or floor void where you cannot reach. You push the tape through, hook the cable on, and pull it back. Cable rods do the same job over longer, straighter runs.

Do I need a torque screwdriver for terminals?

For consumer unit and distribution work, yes, since terminals have specified torques and both overtightening and undertightening cause heat. For a socket faceplate, firm and checked by hand is normally accepted, though the specification still exists.

What is an insulation resistance tester for?

It applies a high test voltage to confirm the insulation between conductors, and between conductors and earth, is intact. It finds damage a continuity test would pass, which is why it forms part of certification rather than casual testing.