ElectricalSafetyOn Site
Construction Site Standards Protect Personnel, Equipment
Construction sites are inherently dangerous. Such locations require special safety measures to protect the project, equipment, and, most importantly, personnel working at or visiting the site. One such safety measure is fairly visible: Everyone wears safety hats. Another safety measure, protection from electrical ground faults, is equally important but not nearly so obvious. Ground faults can result in electrocution or serious burns to personnel, equipment damage, and fires.
The Occupational Safety and Health Administration (OSHA) 29 CFR 1926 404 provides standards for construction site electrical safety. The standard requires that all conductors used for grounding be readily distinguishable from all other power cables; no plugs or receptacles shall be altered to reverse polarity; and no ground terminal or device on receptacles plugs or attachments shall be used for any purpose other than grounding.
Safety Requirements
OSHA 29 CFR 1926 404 also specifies that one of two electrical safety methods — Ground Fault Circuit Interruption (GFCI) devices, paragraph (b) (ii), or an assured equipment ground conductor program, paragraph (b) (iii) — must be used. Although the standard allows a choice between the two, there’s certainly no reason both could not be adopted.
If the GFCI method is selected, the standard specifies use of approved GFCI devices for all 120-volt, single-phase, 15- and 20-ampere outlets that are not part of permanent structure wiring. GFCI receptacles are not required on a two-wire, single-phase portable or vehiclemounted generator rated not more than 5kW, where the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces. Although not addressed by the standard, common sense dictates that all GFCI devices in use on the site be inspected and tested for proper operation at least monthly. Low-cost testers are available that provide status of the device and a means of injecting a ground fault to ensure the GFCI switches power off as intended.
The assured equipment ground conductor program specifies a formal method of inspecting and testing the on-site ground system and maintaining ongoing records and reports. Specific program procedures are described in writing and must be made available to site personnel, visitors, and inspectors. These documents must identify one or more competent persons responsible for program implementation, and items covered by the program, such as cord sets, plugs and receptacles, and associated equipment. It must also identify methods and frequency of inspections and tests as well as what records are kept.
Inspection Criteria
Some specific inspection and test criteria from OSHA 29 CFR 1926 404 (b) (iii) are:
• Each cord set and associated attachments, plugs, and receptacles, as well as any equipment connected by cord and plug, must be visually inspected before each day’s use for indications of possible internal damage and defects such as deformed or missing pins or insulation damage.
• All grounding conductors must periodically be tested for continuity.
• All grounding conductors must be connected to a proper grounding terminal.
The standard provides a complete description of using GFCI devices and the assured equipment- grounding program. It is important to be aware of the existence of the standard and that it provides for several methods of construction site electrical grounding safety. This, in turn, provides for the protection of the project, equipment, and site personnel.
