Circuit Breakers

Resetting circuit breakers in panelboards

Only authorized personnel may access Facilities electrical panelboards to operate circuit breakers in non-emergency situations.

A circuit breaker that automatically trips SHALL ONLY BE RESET by authorized personnel who have access to Facilities electrical panelboards.

Call the maintenance trouble line at 4-2756 for assistance.

Operating circuit breakers in an emergency

Anyone may operate a circuit breaker to disconnect a power source. Fire, electrical shock, or similar threat to life, safety, and property constitute an emergency. Once a circuit breaker is turned off in an emergency, only maintenance personnel may turn it on.

Operating circuit breakers in special situations

Where the only means of disconnecting equipment is in a Facilities electrical panelboard, workers must obtain written authorization from the Electrical Safety Committee prior to operating the circuit breaker.

For routine operations consider having a disconnect installed. For assistance in this process, contact your electrical safety committee representative, Tom Prast.

    Ground Fault Circuit Interrupter (GFCI)

Use GFCIs in high shock-potential areas near water sources. (Click picture to enlarge.)

What is a GFCI?

A ground fault circuit interrupter, or GFCI, is an electrical device designed to detect ground faults. Ground faults occur when electrical current is "leaking" somewhere outside the path along which the current is supposed to flow. If your body provides the path to ground for this leakage, you could be burned, shocked, or even electrocuted.

How do GFCIs work?

• The GFCI constantly monitors electricity flowing in a circuit to sense any imbalance in the current. If the current going into the circuit differs by even a small amount from that returning, the GFCI switches off power to that current.

• The GFCI interrupts power quickly to help prevent you from receiving a lethal dose of electricity. Even with a GFCI, you might be shocked, but the GFCI limits the time and current to which you are exposed and helps protect against serious injury and electrocution.

• The main purpose of a GFIC is to protect personnel.
  
  
  

GFCI Toubleshooting

GFCI (on the right) is protected at the breakerbox and labeled GFCI Protected. (Click picture to enlarge.)

If a GFCI breaker trips, it could be caused by a short circuit, or an overload circuit, or due to a leakage path to ground.

• If it tripped while you were using a tool or appliance, that tool or appliance is most likely to be the trouble source. Unplug it, reset the GFCI, and test the circuit.

• If the GFCI device remains ON, do not use the tool or appliance until it has been professionally repaired.

• If the GFCI does not remain ON, unplug all loads on the circuit one at a time, resetting the GFCI and testing the circuit each time. If you locate the trouble source this way, do not use the lamp, tool, or appliance until it has been professionally repaired.

• If you have not located the trouble, your wiring system may be leaking to ground or misconnected, and should be checked by a licensed electrician.

GFCIs should be tested every month or so. You can do this by pushing the bottom marked "test ."
The test button will activate or trip the reset button to show that the device is working.
Then push the reset.

Note: GFCI devices will trip immediately if the neutral wire of its load circuit touches or connects to ground or the neutral wire of another circuit.

    Extension Cords & Plug Strips

Temporary Wiring (Extension Cords and Power Strips)

• The use of extension cords and power strips is not intended to provide for unlimited rearrangement of user space and addition of equipment.

• A shortage of electrical receptacles or or the inconvenient locations of them creates short-term problems that may be solved by the proper use of extension cords and power strips. Use of an extension cord falls under the catagory of temporary wiring.

  Classic computer workstation installation? (Click picture to enlarge.)

  If the use of an extension cord is for other than the short-term solution of a situation, it is necessary to request the addition of permanent receptacles.
• Power Strips (Portable Power TAps, Temporary Power Taps, Portable Outlet Strips) are acceptable for use where several electrical or electronic devices need to be plugged-in within close proximity. This is usually the case in our modern electronic offices where computer systems require several receptacles. Newer power strips are available that have 15 foot cords and 10 outlets if the traditional 6-outlet / 6-foot cord is not sufficient for your needs. Currently, our JIT electrical supplier recommends Wiremold model UL210BD These units contain a circuit breaker, lighted switch, and are UL listed.

If It Looks Bad, It Probably Is!

• Worn-out power strips, cracked or worn insulation, and damaged receptacles are fire and shock hazards as witnessed by several Sandians at work and at home. When receptacles wear out, the plug does not hold tightly and heat starts to build up. This can cause the plastic to melt and if not caught in time, a fire may result. The excess current required for this heat is not enough to trip a circuit breaker. A GFCI is no help in this situation either.
• If the prongs on a recently extracted plug are warm to the touch, you may have this problem. This test may not apply to a plug-in transformer with integral prongs that normally gets warm during operation.
• Receptacles can wear out whether they are in power strips or are part of the permanent wiring.
  If plugs do not hold tightly, get a new power strip or have the receptacle replaced!

Guidelines for using extension cords are as follows:

• Extension cords should be used for temporary power distribution only.
• The UL listing for extension cords calls for the cord to be removed from its wrapping and extended for its entire length. This is to eliminate heat build-up from a bundled cord that could be a fire hazard. Likewise, equipment cords should not become a "rat's-nest" under desks and workbenches.
• Protect extension cords from damage.
• If extension cords, power strips, or equipment cords become damaged, do not use them! BUY NEW ONES!
• Use only a single extension cord to supply a temporary power tap.
• Do not connect temporary power taps (commonly called power strips or surge protectors) in series.
• Remove extension cords and flexible cords upon completion of the work.
• Prior to use, inspect all extension cords for damage such as deformed or missing pins or damaged outer jacket or insulation.
  Damaged cords shall be removed from service.
• Do not use cords to raise or lower equipment.
• Cords shall not be fastened with staples or any other object that could damage the outer jacket or insulation. They shall not be used under carpets or inside walls, floors, or ceilings, or run through holes in walls, floors, or ceilings.
• The ground pin connection on 3-wire cords must always be maintained.
• Do not alter attachment plugs and receptacles; call maintenance at 4-2756 for assistance.

Guidelines for selecting extension cords are as follows:

• Use only NRTL listed extension cords, or cords assembled by a qualified person using NRTL listed components.

• Do not use adapters which interrupt continuity of the equipment grounding conductor.

• Do not splice cords containing No. 12 AWG or smaller wire. Extension cords with No. 10 AWG or larger conductors shall be spliced with UL listed splice kits.

• Do not use an extension cord in excess of its rated ampacity. See Table 2-5 for wire size and length versus ampacity information.

The figure below demonstrates a proper cable installation.