In the United States, there is strict compliance for the electrical wires to use color-coding to determine the purpose of the wire. Black indicates the wire is hot or live, White indicates the wire is neutral, and Green will show the wire to be ground or earth.
On occasions, you may find yourself with two black wires, or you may not know your regional wiring color coding standard. Typically, you would use a multimeter to determine the hot wire from neutral. But what if you do not have a multimeter.
Let me share some insight into how to tell which wire is hot without a multimeter.
Always Presume Wires Are Live
The first and most important point is to always presume all wires are live. Taking this approach will mitigate some risks. Never touch a wire with your hand to test it. This can lead to serious injury or even death.
Testing Which Wire Is Hot Without a Multimeter
There are several ways to test for a live or hot wire, so let’s work through the most effective ways of doing this when you do not have a multimeter to hand.
- Regional Wire Color Coding Standards
- Using a Test Screwdriver
- Build a Voltage Tester
Know Your Regions Wire Color Coding Standards
Most regions use a color-coding standard, if you plan on working with electrical circuitry then it is essential you become familiar with wire color code basic guidelines. All wiring, AC and DC, should follow these guidelines.
In the United States of America for example a single-phase system has two wires:
- White Wire is Neutral (N = neutral)
- Black Wire is Hot (L = load)
Sometimes you will also find a bare wire or green wire, this will be the Ground Wire (PG = Ground).
But it does get slightly more complex for non-residential properties that often use a 3-phase system:
| Function | label | Color, common | Color, alternative |
| Protective ground | PG | bare, green, or green-yellow | green |
| Neutral | N | white | grey |
| Line, single phase | L | black or red (2nd hot) | |
| Line, 3-phase | L1 | black | brown |
| Line, 3-phase | L2 | red | orange |
| Line, 3-phase | L3 | blue | yellow |
An in-depth schematic of regional wiring codes can be found here.
Use a Tester Screwdriver
Tester Screwdrivers are a simple device to test a wire for current. Use the tip of the screwdriver and place it on a bare section of uninsulated wire, to see if it holds current. The screwdriver is designed to allow enough current to flow through it and light up the neon bulb contained within the handle.
If the neon bulb glows, then the wire is live. This indicated that the wire holds more than 50 volts of current.
Build Your Own Non-Contact Voltage Tester
I will preface this section with the presumption that you are not an electrical engineer otherwise you would not be reading this article…right? So do not try this at home! But just out of interest it is possible to build your own Voltage Tester.
Stay Safe Use a Voltage Meter or Multi-Meter
Multimeters are not expensive tools, so there is no excuse to try and take shortcuts. For under $10 you can protect yourself and do the job properly. Check out this short video to demonstrate just how easy they are to use.
Risks of Accidental Contact with Household Current
Working on household electric circuits presents a genuine health risk and should be treated seriously. 110V is considered low voltage within the context of 500V high voltage current and 100,000V industrial power lines. However, direct contact with 11V can lead to serious injuries and potential death.
These are some common outcomes from contact with household electrical points:
- Arc Flash: A flash injury usually occurs because of an electric arc touching the persons skin causing superficial burns. In this situation the current would be weak and would fail to penetrate the skin.
- Flame: An electrical arc may come into contact with clothes or surrounding fabrics, leading to fire and consequential personal burns to the skin
- Lightning Bolt: This is a more intense current that penetrates the skin and travels through a person body resulting in seizures and potentially life-threating changes to the hearts rhythm
- True: When a person is caught between two points and effectively joining an electrical circuit as the electricity travels through their body potentially leading to a fatal outcome.
The injury sustained will be dependent on several factors including:
- The type of contact with the electrical outlet
- The duration of the contact with the electrical current
- The intensity of the electrical current
- Environmental factors such as moisture
- The part of the body in contact with the current will also affect the outcome of the injury
Short Term Side Effects of Contact with Electric Current:
- Burns
- Irregular Heartbeat
- Muscle Seizures
- Loss of Consciousness
Finally, How To Tell Which Wire Is Hot Without A Multimeter
There are ways to tell which wire is hot without a multimeter or voltage tester. Each of them is safe if performed in the correct manner.
Remember the danger is ever-present when working with electricity. If you do not have the necessary experience or skills to carry out electrical work, then leave it to someone qualified.