How to Safely Check If a Wire is Live

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How to Safely Check If a Wire is Live (or Hot)

There are many ways to determine if an electrical cable is live. You may need to do so if you are renovating, experiencing an electrical fault, or installing a new light switch. Regardless, you must carry out the task with utmost care and attention-to-detail.

When you are dealing with electricity it is important to stay safe. Even a minor lapse in judgement can put you at risk of serious injury or death. Especially if you are confused by the layout of your wiring or the wiring is disorganised due to the poor workmanship work of a previous electrician. 

For this reason, if you are not absolutely confident in your ability to handle an electrical system, hire an electrician who will do the job right. If you wish to proceed then here is everything you need to know.

Types of Voltage Testers

The safest way to check if a wire is live is to purchase a voltage tester. Of which there are many types to choose from. They will help you determine whether there is current flowing through a wire. These inexpensive devices are readily available to buy online and at your local hardware store.

Here are the most common types of voltage testers and how to use them.

Non-contact voltage tester

This voltage tester is the safest way to test if a wire is live. The device itself is similar in shape and size to a sharpie. Also, it is lightweight and made of durable plastic resin construction, making it easy and safe to use.

The main benefit of this voltage tester is that the first step does not require you to touch any wires. Instead, you simply turn off the power and insert the device into the narrow slot of an electrical outlet, which will then cause the device to light up and chirp continuously if there is still power.

From there, if you need to investigate a particular wire in a power outlet or anywhere else, you can again place the device near the wire then wait for the device to light up and chirp again.

Perhaps the only downside to this voltage tester is that it cannot test wires covered by metal sheathing or conduit. They also typically run on batteries so make sure you have a spare pair on hand.

Digital Multimeter

A multimeter is an electronic tool used to measure voltage, resistance, and amps. You can alternate between different electrical units on the fly by simply turning the knob. For the sake of this test have the device set to measure AC voltage.

To test a wire or other piece of electrical equipment, you use the two probes attached to the device: one red (positive) and the other black (negative). Before you check whether a cable is live switch the power off first. Whatever reading the device picks up is conveniently displayed on the LCD screen for you. 

When would you need to use a multimeter over a non-contact voltage tester? 

These devices are particularly useful if you work or live in an older premise, and you want to know if an equipment ground wire is actually connected to the grounds within the system. You can also use the non-contact voltage tester first as a means to test an electrical outlet before you investigate the wires.

How to Safely Check If a Wire is Live

Every residential, commercial, and industrial premise in Australia must be compliant with the current Wiring Rules AS/NZS 3000. 

While these standards cover a broad range of minimum requirements which involve safety, adapting to new technology, and improved installation methods, for you it means that your electrical wiring – from the layout to the individual colour codes – should be consistent across the board.

The colour scheme of your wiring system is determined by whether the system is single phase or multiphase. Most domestic homes have a single phase system (where the electricity is connected at 230 to 240 volts) while most industrial sites and large commercial premises have multi-phase (where electricity is connected at 400 to 415 volts).

Below is a single breakdown of the colour codes for single phase and multiphase:

Current Australian colour code for single phase  

  1. Active – Red
  2. Neutral – Black
  3. Earth – Green/Yellow

Current Australian colour code for multiphase

  1. Phase 1 – Red
  2. Phase 2 – White
  3. Phase 3 – Dark Blue
  4. Earth – Green/Yellow

If you plan to examine the wiring of your residential or commercial premise then you must be familiar with the colour code for your premise. 

Whichever device you use to test an electrical cable, make sure the Earth wire is always connected correctly during the job. The purpose of this cable is to save your life in the event of a surge or short. 

For DIY testing you should only test the Active (Red) wire to find out if it is live (or hot).

Talk to the Experts

If your electrical system is a multiphase setup, or you suspect that your electrical issue could be serious, enlist the help of a fully licensed electrician. 

By using the latest technology and following safe industry practices, they can quickly determine the cause of the fault and provide a solution for you.

Sydney Electrical Service are experts in fault finding and electrical cable testing. To request a FREE quote call (02) 8755 2621. Alternatively, fill out the online form. And one of our friendly electricians will get straight back to you.

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Rami Alcheikh
Rami Alcheikh

In Sydney Electrical Service, Rami works on the content team. He is passionate about sharing tips that can help make your electrical projects easier.

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