Electrical extension cords and power strip requirements

Dedicated surge-suppressor outlets are preferred over power strips for permanent applications.

Surge suppressors (and power strips with surge protection) must be UL 1449 listed, plugged directly into a wall receptacle. Relocatable power taps (ie: power strips) must be UL 1363 listed, plugged directly into a wall receptacle.

Not all surge protectors/suppressors are equipped with overcurrent protection. A device with overcurrent protection has an electric circuit that prevents damage resulting from excessive current, interrupting the flow of current at a predetermined value.

Surge protectors/suppressors can be used for specific equipment. In the view of the State Fire Marshal, surge protectors/suppressors which are not equipped with overcurrent protection are considered a multi-plug extension cord and cannot supply electrical service to other equipment, a relocatable power strip or an extension cord.

Units with 15 and 20 amp circuits are available:

• 15 amp is suitable for office applications
• 20 amp is appropriate for lab and industrial applications
• A 20 amp circuit breaker is necessary when using a 20 amp strip/suppressor
• Power strips are not approved in chemical fume hoods
• Multiple power strips in series (Daisy chaining) is not allowed and subject to a fine by Fire Marshal

Evaluating power strip/suppressor capacity:

The total loading of all connected appliance must not exceed the capacity of the device. The National Electrical Code specifies a circuit should only carry 80% of its rated load during normal operations.

An example of determining capacity for a 15-amp strip in office setting:

Two desk-top computers, 500 Watts, Watts/Volts = Amps

Two 19 Inch LCD displays, 80 Watts, 640 Watts/115 volts = 5.6 Amps

Desk Lamp, 60 Watts, 5.6/15.0 Amps = 37% of capacity

Total = 640 Watts

Extension cords are for temporary use only, typically for portable devices, or short-term, temporary events.

• Do not use in lieu of permanent wiring
• Do not use with refrigerators, ice machines, or other high amperage appliances including portable space heaters. Space heaters, if allowed shall be plugged directly into a wall outlet. Refer to the KU space heater policy

Some buildings may not have the infrastructure to meet all operational needs. In these cases power strips and surge suppressors may be possible. In other cases it may be necessary to expand the building’s electrical system.

Extension cords requirements:

• Underwriters Laboratory (UL)-approved. (UL 817 indoor, and UL 2438 or ‘W’ for outdoor)
• Minimum 16 gauge, double insulated, grounded, and no longer than needed
• Polarized electrical appliance with polarized plugs are approved. (Polarized plugs have 2 prongs with one prong larger than the other)
• Recommend no longer than 100 feet for light duty, and 50 feet for medium duty
• Do not exceed the amperage rating of the cord (See table below)
• Do not use where flammable or explosive atmospheres exist

A smaller “gauge” number indicates a thicker cord:

• 18 gauge (not approved for lab or industrial use)
• 16 gauge (light duty) for equipment up to 13 amps (e.g., portable lights and fans)
• 14 gauge (medium duty) for 14 to 15 amps, such as portable power tools
• 12 gauge (heavy duty) for 16 to 20 amps
• 10 gauge (extra heavy duty) is for air compressors, electric chain saws, etc.

Any defect or damage to a cord, power strip, or any electrical component places it out of service and most be disposed and replaced.

Inspect for visible damage, as well as warm connectors, plugs, and cords. If plugs or cords are warm to the touch an excessive amount of current is flowing through the connection due to excessive resistance and/or ‘over-Amp’ conditions. The National Electrical Code limits loading to 80% of capacity to minimize problems from excessive resistance and ‘over-Amp’ conditions.

Poor contact between device contacts and plug blades may cause a plug to heat up by increasing resistance. Damage to cord wire may increase resistance and cause heat. Multiple connection-to-plug conditions (Daisy-Chaining) increases current needed at the far end of the chain in order to overcome each point of resistance. Damage to an appliance’s electrical system also cause units to "over-Amp."

These actions will greatly decrease the risk of electrical shock and fire:

• Plug adapters are not approved
• Plug power strips/suppressors/extension cords directly into a wall receptacle
• Always grip the plug to disconnect from an outlet. Do not pull by the cord itself
• Never place cords where they will be driven or ridden over by a vehicle of any kind
• Never kink, knot or twist cords.
• Provide a bridge for temporary cords placed across walkways and circulation paths to protect the cord and prevent a tripping hazard. Other methods, such as duct tape, are less effective.
• Do not place cords over sharp or abrasive materials
• Do not use in wet locations
• Do not use multiple power strips in series (Daisy chaining)
• Do not connect power strips to extension cords
• Do not permanently secure to walls, ceilings, table legs, or similar structures. (Nails, tacks, zip-ties, staples or other methods which may damage cords). It is permissible as long as no tool is required to remove the device
• Do not run flexible cords through walls, ceilings, floors, or windows, over drop down ceilings, or under doors, carpets or rugs, or false floors. This is a fire code violation and the condition of the cord cannot be verified if it is hidden from view.