By Brett Miller, NWFA Vice President Technical Standards, Training & Certification
Electrical hazards can be found on nearly every jobsite. Whether the hazard is posed by damaged or worn power tools or cords, improperly grounded tools, or the power sources themselves, it is critical to understand the potential electrical dangers on the jobsite.
Here are seven common items that must be checked and followed while on the jobsite for electrical safety.
The most-often overlooked electrical safety precaution is knowing what the power requirements are for each piece of equipment on the jobsite. It is important to read the operations manual for all equipment and understand what the electrical requirements are for each individual power tool.
Circuit Breaker Panel
The circuit breaker panel should be the first electrical item assessed on the jobsite and should be completed before any work is done. Here you should be able to determine whether proper power is available for the equipment you will be using on the job. To make this assessment, a basic understanding of how a circuit breaker panel works is needed.
- Neutral and hot wires: Current flows from the panel toward the load along the hot wires and returns along the neutral wires. The copper tip of each hot wire connects to its control switch at the circuit breaker, and each neutral wire connects to a common terminal.
- Main breaker: This is the on/off switch to the entire breaker panel. A 200-amp breaker is common for a home of 2,000 square feet. Smaller buildings may use 150-amp or 100-amp; small homes and subpanels can use as little as 50-amp.
- Double-pole breaker: Uses the entire 240 volts available to the panel. The 15-amp breakers often handle baseboard heaters, 30-amp serve water heaters and electric dryers, 40-and 50-amp are for electric ranges, and the 70-amp could serve a large air conditioner or a subpanel.
- Single-pole breaker: The 15-amp and 20-amp are all-purpose breakers, running everything from lights and outlets to the garage-door openers.
- 15-amp AFI breaker: Arc-fault-circuit-interrupter breakers can prevent fires caused by accidental electrical discharge.
- Ground wires: Grounding prevents a conductor not meant to carry current (such as the metal side of a clothes dryer) from causing injury if it’s energized by a frayed hot wire. In a properly grounded system, appliances and metal boxes connect back to the grounding bus of the breaker panel. From there, the system is grounded to the earth via buried ground rods.
If after evaluating the circuit breaker panel you are still unsure of power capabilities, you should hire a licensed electrician to set up electrical connections.
A multimeter, also known as a VOM (Volt-Ohm-Milliammeter), typically measures voltage, current, and resistance. Always keep a multimeter on hand to test for proper voltage at power sources and through cords. Ensure power at the jobsite is sufficient for the equipment being used. If insufficient power is detected, the use of a power booster can help deliver adequate power to the tools being used.
Under-powered or overpowered power situations will cause wear and tear on any piece of equipment, reducing its life span. A power booster is an inexpensive insurance policy for ensuring the equipment being used is being run properly. It will help monitor and deliver adequate power to the tools being used. Power boosters usually include volt meters, multiple setting voltage adjustments, circuit breakers, and both 220 and 110 outlets for flooring equipment.
You should know the basics of the different types of power available at any jobsite. In the United States, 15- or 20-amp breakers are common. These are all-purpose power sources that run lighting and outlets. 30-, 40-, and 50-amp breakers are common power sources for electric dryers, electric ranges, or other large appliances. The type of plug in the wall will be dictated by its use. Have adapters made prior to arriving at the jobsite to be able to connect to each type of outlet. Also, consider the type of power you are attempting to plug into in relation to the equipment you will be using. Note: Power sources and requirements will differ in other countries.
The quality of cords can be easily overlooked, which can cause serious repercussions if not addressed. Check cords regularly for damage or deterioration. Are they cut or cracked? Do they have broken insulation? Check and tighten connections on the plugs and connectors regularly.
There are safety regulations you must follow on the jobsite in relation to extension cords. One cannot just use any extension cords lying around on the jobsite. OSHA requires three-wire extension cords at all jobsites. These three-wire extension cords are designed for hard or extra-hard usage.
Ground-fault circuit interrupters (GFCIs) must be used on all projects for 120-volt, single-phase 15-, and 20-amp services. When using a generator or temporary pole, a GFCI is required, or a portable unit must be used.
When the grounding pin on a plug of a power tool is missing, repair or replace it before using the cord. Using a tool with a missing grounding pin can be extremely dangerous for the user. If a short were to develop in the tool, the user may become the ground in the system and the electricity may travel through him or her.
Wire gauge is a measurement of how large a wire is, either in diameter or a cross sectional area. This determines the amount of electric current a wire or extension cord can carry safely as well as the electrical resistance and weight per unit per length.
Select the proper gauge cords for the machinery you will be using. Longer distances will require heavier gauge cords and/or use of a booster. When improper gauge cords are used, plugs, wires, and equipment motors can overheat, causing permanent damage. The size of the wire in an extension cord set must be enough to handle the amperage that will be drawn by the tools connected.
Never place any cord around your neck or over your shoulders. It is unsafe, and if the cord has a nick or cut in the insulation, it could get wet from sweat and short out. It also can cause body fatigue and muscle fatigue. Our body is a DC current and the power source is an AC current, meaning it will interrupt the flow of current in our body. This causes muscle fatigue.
It is important to disconnect all power when leaving the jobsite. The cord itself should never be pulled to disconnect it from the power source; instead, remove it by the plug.
If these seven items are not checked and followed while on the jobsite, electrical fires could be the result. Class C electrical fires are caused by faulty cords, loose connections, breaker box fires, bad switches, faulty equipment, or improper cord selection.
The National Wood Flooring Association has detailed information about safety on the flooring jobsite available through NWFA University, a convenient and affordable online training platform. More information is available at nwfa.org/nwfa-university.aspx.