Preventing Electrical Equipment Hazards I. Insulation Non-conductive material around conductors – wire insulation (THHN, SOW) Insulation materials in tools and motors (single and double) Air gap is normally the second insulation in double insulated tools Breakdown of insulation results in contact with live conductors Insulation materials in tools become saturated with carbon brush dust – arc trail …Insulation may be damaged by hard usage on the job or simply by aging. If this damage causes the conductors to become exposed, the hazards of shocks, burns, and fire will exist. Double insulation may be used as additional protection on the live parts of a tool, but double insulation does not provide protection against defective cords and plugs or against heavy moisture conditions. - OSHA
Preventing Electrical Equipment Hazards II. Grounding Grounding conductors can be cut, panel ground bad, ground pins pulled out, etc Plugs replaced on portable tools can be wired incorrectly Metal gang (job) boxes used as portable power are extremely dangerous! …Consider, for example, the metal housing or enclosure around a motor or the metal box in which electrical switches, circuit breakers, and controls are placed. Such enclosures protect the equipment from dirt and moisture and prevent accidental contact with exposed wiring. However, there is a hazard associated with housings and enclosures. A malfunction within the equipmentsuch as deteriorated insulationmay create an electrical shock hazard. Many metal enclosures are connected to a ground to eliminate the hazard. If a "hot" wire contacts a grounded enclosure, a ground fault results which normally will trip a circuit breaker or blow a fuse. Metal enclosures and containers are usually grounded by connecting them with a wire going to ground. This wire is called an equipment grounding conductor. Most portable electric tools and appliances are grounded by this means. There is one disadvantage to grounding: a break in the grounding system may occur without the user's knowledge. - OSHA
Double insulated tool issues: Carbon dust trails Moisture trails Cracked housings Miswired plugs Drill chucks are connected to the armature – metal Cord fraying Strain relief damage Anatomy of an Electric Shock GFCI shuts off power in 25 msec to prevent injury Faster than the human can sense an electric shock!
Metal Gang Box Death Trap Line of Protection Protected NOT Protected GFCI Problem # 1 Loss of Ground (ungrounded box) Problem # 3 Cord damage Problem # 4 Ground at panel Neutral bond bad Problem # 2 Hot wire touching box Code Violation Metal gang boxes are for PERMANENT INSTALLATIONS ( non-moving) Use rubberized boxes that are UL tested for Portable Power Tap use Use GFCI inline near the plug or at source
Anatomy of a GFCI LineLoad H N.5 amp Relay Sense ring Electronics Target = > 6 mA.4 amp Gnd Rules of GFCI: - 6 mA max - 25 mSec release - break both sides of the line
OSHA REQUIREMENTS OSHA ( 29 CFR) 1926.404(b)(1)(i) General. The employer shall use either ground fault circuit interrupters as specified in paragraph (b)(1)(ii) of this section or an assured equipment grounding conductor program as specified in paragraph (b)(1)(iii) of this section to protect employees on construction sites. These requirements are in addition to any other requirements for equipment grounding conductors. Ground-fault circuit interrupters. All 120-volt, single-phase 15- and 20-ampere receptacle outlets on construction sites, which are not a part of the permanent wiring of the building or structure and which are in use by employees, shall have approved ground-fault circuit interrupters for personnel protection. Receptacles on a two-wire, single-phase portable or vehicle-mounted generator rated not more than 5kW, where the circuit conductors of the generator are insulated from the generator frame and all other grounded surfaces, need not be protected with ground-fault circuit interrupters. Assured Equipment Grounding Continuity Program – cover next month E.U. Session
Interpretation Letter from OSHA (dated May 2002) states the following Q & A: Question (1): Does the requirement in 29 CFR 1926.404(b)(1)(i) to have either a ground-fault circuit interrupter protection (GFCI) or an assured equipment grounding conductor program (AEGCP) apply only to 120 V circuits, or does it also apply to a 240 V circuit? Answer: Yes. §1926.404(b)(1)(i) provides: (b) Branch circuits -- (1) Ground-fault protection - (i) General. The employer shall use either ground fault circuit interrupters as specified in paragraph (b)(1)(ii) of this section or an assured equipment grounding conductor program as specified in paragraph (b)(1)(iii) of this section to protect employees on construction sites. These requirements are in addition to any other requirements for equipment grounding conductors. Under this provision, employers must provide protection against ground-fault by using either a GFCI or AEGCP. The provision, by its terms, is not limited to 120 V circuits. Employers are required to protect employees under this provision with respect to 240 V circuits as well. Question (2): What are the requirements when a temporary service panel has both a 120 V and a 240 V circuit? Would protecting the 120 V circuit with a GFCI comply with the standard, or does the 240 V circuit also have to be protected by a GFCI or an assured equipment grounding conductor program? Answer: The 240 V circuit must be protected as well. Installing a GFCI designed for a 120 V circuit in a panel that also has a 240 V circuit will not provide ground-fault protection to the 240 V circuit. While technically the option of using GFCI under (b)(1)(ii) is available only for 120 V circuits, that limitation was put in the standard only because GFCIs for 240 V were generally unavailable when the standard was promulgated. Employers may choose to use GFCIs designed for 240 V to protect 240 V circuits; the technical violation of (b)(1)(ii) would be considered de minimis. De minimis violations are those which have no direct or immediate relationship to safety or health. Citations are not issued for de minimis violations.
GFCIs and NEC 2008 Article 590.6 calls for basically all receptacles that are in use to be GFCI protected. Again OSHA considers this violation minor and citations are not being given at this time.
GFCIs and Lighting OSHA does not call for lighting circuits to be GFCI protected. NEC 525.23(c) specifically states that egress lighting shall not be GFCI protected.
Auto vs Manual Auto = Auto powerup start Manual = Manual powerup start –R–RESET button serves as initial start button ALL GFCIs must be physically RESET after a fault trip Automatically Reseting GFCIs do not exist
GFCI Offerings Commercial Grade Industrial Grade Custom Industrial Grade Add-a-cord Some corded models Inline Style90 Degree PlugPanel Mount
Distribute Point to Point Only Distribute Multiple Taps Cordsets Y W Power Stringers Distribute with GFCI Protection GFCI 1060/1070 Distribute / Split Phases / GFCI Protection 6000 7000 8000 Series Distribute / High Power ( 480 or 600 V ) Oscars Gen Cords Big-E Jr Big-E 480V Big-E Transform / Distribute / GFCI Protect e-Cart Jr. e-Cart