Chapter Corner

Temporary Power in Construction

Posted in: Features, May/June 2015

lights.gifTemporary electrical power systems during the construction phase can be equally as dangerous as any permanent installation, especially when installed by non-qualified electrical workers. This is why it is important that all installations regardless of their intended use be installed in a good craftsmanship manner. As we have all come to understand, a code-compliant installation is a safe installation.

Let’s think about this for a second, if temporary power systems during the construction are not installed to National Electrical Code (NEC) standards, the general public, structures, and workers could be affected. This is not in the best interest of any electrical contractors.

This article will share some of the basic steps in the process that will increase the successful installation of a temporary power system.

The success of an electrical contractor starts with mapping out an approach to temporary power systems from the design through to the electrical system turn-over to the customer.

There is one supplemental document that can be extremely resourceful when it comes to temporary installation in construction and that is NECA 200 Standard for Installing Temporary Electric Power at Construction Sites.

PLANNING

The pre-planning starts with reviewing all applicable standards, such as the version of the NEC that applies to the construction project. Other standards that are often overlooked are OSHA Standards such as Subpart K or NFPA 70E. The basic assumption is that electrical installations installed and used during the construction phase are subject to interaction with qualified electrical workers and non-qualified electrical workers.

Pre-planning with an end in mind is always worth the time and effort. It is often said that failing to plan is planning to fail. Critical answers must be sought at the planning stage such as:

(a)When must temporary power be available on site?

(b)What power supply needs are required during each phase of the construction cycle?

(c)When does the electrical system transfer to permanent power?

While many of these seem simple, customer expectations and electrical contractors’ views are not always aligned. Often this misalignment results in a bad experience for customers.

INSTALLATION

Part of the planning process includes site layout. Property boundaries, planned construction areas, construction offices, and temporary parking can affect temporary power. These and other critical areas need to be identified prior to commencing temporary power distribution. An electrical contractor’s worst nightmare is having to move temporary power on multiple occasions. This is not good because it can often lead to placing electrical workers in positions that might involve interacting with the electrical hazard.

It is always best to coordinate the use of permanent raceways with the temporary power installation. This will reduce transition time when it’s time to transfer to permanent power. An added bonus to this approach is reduced contact time with an electrical installation and a safer working environment for electrical workers.

OTHER TRADES

Coordinating with other trades is of the utmost importance before the Notice to Proceed (NTP). This will ensure that the installation considers special equipment needs for other crafts and can present an opportunity for added temporary power funds. The last thing a customer wants to experience is an electrical system that is not sufficient for the project needs. This often costs time, money, and leads to poor customer development.

GROUND FAULT PROTECTION OF EQUIPMENT

Ground fault circuit interrupters (GFCI) should be installed to protect personnel onsite. While it is not the responsibilities of the electrical contractor to protect other trades, it is a good practice. This will ensure that non-qualified electrical workers do not become part of the circuit in case electrical cords are damaged. The location of GFCI devices might trigger other requirements such as providing covers and the testing to ensure GFCI protection is maintained.

All electrical equipment needs to be installed with protection from environmental conditions in mind. If equipment must be installed outdoors, install equipment with canopy and covers. Minimize exposure to solar heating, water, snow, and ice.

PHYSICAL BARRIERS

Depending on the location of installation, physical barriers might be needed to protect electrical systems. Make sure to maintain minimum clearances on all electrical equipment. These clearances must be maintained throughout the entire lifecycle. This includes the maintenance of adequate lighting. Lighting requirements can be found in Table D.2 in the 29 CFR 1926.

SIGNAGE

As the construction phases progress, signage will become necessary. These are administrative controls that warnnon-qualified workers of potential hazards. Signage might be needed in electrical rooms, electrical panels, and overhead power lines. These are just a few items to consider.

TEMPORARY LIGHTING

Lighting during the construction process is critical. The location of lighting is important because light levels must be maintained during the entire life cycle. Lighting cages, if used, need to be supported as per design specification and bulbs must be protected from accidental damage. This is often accomplished with the installation of plastic or metal cages.

Keep in mind that as the project progresses, if lighting is not installed at an appropriate height, there will be conflicts with other trades, which will most likely impact the lighting levels during construction.

This article shares some of the key requirements that affect temporary power installations but it is not intended to be all encompassing. Before beginning work make sure that you review the applicable NEC, NFPA 70E, NECA 200, and other applicable standards.

Jerry Rivera has over 20 years of electrical construction safety experience. He is a current member of the Advisory Committee on Construction Safety and Health (ACCSH) a position appointed by the Assistant Secretary of Labor, Dr. David Michaels. He has served on the NFPA 70E, ANSI/A10, and IEC National Safety Committee. He is currently certified as a Certified Electrical Safety Compliance Professional (CESCP) and Certified Electrical Safety Worker (CESW) by the National Fire Protection Association.