Preparing for an Arc Flash Study – Part 2

Last month we discussed how to prepare your electrical workers, management and yourself mentally for what is involved in implementing the requirements of NFPA 70E. This article goes over some practical ways to prepare such as gathering the needed documentation and deciding on policies and procedures.

Every thorough arc flash study involves gather a lot of electrical system information needed to build the arc flash study computer model. A lot of this information may already be available in the form of drawings, equipment test records and other equipment documentation. Gathering and organizing this information can save time and therefore, reduce the cost of an arc flash study.

What Documentation to Collect

1. Single-line Drawings – Single-line drawings represent the three-phase electrical system with a single line per phase, thus the name, and are a simplified representation of the electrical system. They are like a road map. They look like an upside down tree. The trunk is the single source of power into the plant and the branches spread out to the far reaches of the facility’s electrical distribution system.
2. Circuit Breaker and Relay Test Records – If you have been performing testing on your circuit breakers, relays and other equipment, test records should exist which contains a lot of information about the equipment and the settings. This information is necessary to perform an arc flash study.
3. Previous Electrical Studies – Many large facilities have had some type of electrical engineering study. These studies may have been called Short Circuit Study, Coordination Study or Load Study. There may even exist a previous arc flash study that has become outdated. These studies contain an extensive amount of information. Even if the study is rather old, there often is information that can be used as reference or background for the arc flash study.
4. Infrared Inspection Reports/Thermography – Most facilities are conducting infrared inspections or thermography on their electrical equipment. These reports may contain equipment nameplate information that is useful for an arc flash study.
5. Equipment Lists – Many facilities keep inventory of the motors and other electrical equipment that are helpful for an arc flash study. The connected motors are important to include in the arc flash study model because they affect the arc flash hazard calculations.
6. Utility Data – To perform an arc flash study the electrical characteristics of the utility supply is needed. This information can be obtained by requesting it from your electrical utility company. This can take some time for them to supply, so it is important to request the information early or it may delay the completion of the study.

Arc Flash/Electrical Safety Policy and Procedures

An arc flash policy is a written document which details the company’s beliefs and requirements concerning energized work and electrical safety. The written document is required by NFPA 70E and spells out the electrical safety program. It lists requirements, responsibilities and procedures to follow for the employees and contractors.

Click here to see a template to follow for writing an Arc Flash/Electrical Safety Policy.

It may take some time to get agreement on the new program, so it is helpful to get started early. 

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