Electrical - Installation Of Wiring System

Wiring in Steel Conduit System

1 Type of Cable

Wiring system installed in conduits shall be non-sheathed copper cables. Cables for 3 phase circuit shall be 450/750V grade or above.


2 Concealed Steel Conduit System

Unless otherwise specified in the Particular Specification or on the Drawings, conduits shall be concealed within walls, floor slabs, false ceilings, or other suitable space.
Chase for conduit to be concealed in wall, column or beam shall be vertical or horizontal.


3 Surface Conduit System

Where surface conduits are specified, they shall be fixed by distance (spacing) saddles, and shall run in a vertical or horizontal direction.

Conduit boxes, adaptable boxes and metal boxes for accessories shall be securely fixed to walls, ceilings or other substantial parts of a structure by means of suitable brass screws correctly spaced. The fixing of these boxes shall be independent of the fixing of the associated conduits.

Particular precaution shall be taken in situations where the high temperature cables may be touched, or where they may touch other materials.


4 Minimum Size of Conduit

The minimum outside diameter of any conduit shall be 20mm.


5 Flexible Conduit

Flexible conduit shall be used as short as possible and in any case shall not exceed a conduit run of 2m. (Note : PVC pliable conduit may be used in place of steel flexible conduit wherever appropriate. In such case, requirements in Sub-section B1.3 shall apply.)


6 Conduit Continuity

The steel conduit installation shall be mechanically and electrically continuous throughout and effectively earthed. Where the circuit protective conductor is formed by the conduits, the terminal of a socket outlet shall be connected by a separate circuit protective conductor having the same cross-sectional area and type as the live conductor to an earth terminal incorporated in the associated
metal box or enclosure.

Flexible conduit shall not be used as a circuit protective conductor. A separate circuit protective conductor having the same cross-sectional area and type as the largest live conductor shall be drawn into the flexible conduit for earth continuity. This circuit protective conductor shall be fixed to an earth terminal incorporated, at each end, in the metal boxes or enclosures onto which the ends of the flexible conduit are locked.


7 Joint in Conduits

Joint in steel conduits shall be made by means of a solid coupler into which the adjacent ends of the two conduits shall be inserted to approximately half into it and screwed up tightly in order to make the conduit run mechanically and electrically continuous. No threads on either conduit shall be exposed.

Running couplings shall not be used. In case where such a coupling cannot be avoided approval from the Architect must be obtained before it is adopted. In this case, the coupler shall be screwed up tightly onto the short threaded portion of one conduit, the threaded portion of which shall project approximately half way into the length of the coupler. The threaded portion of the mating conduit shall also project approximately half way into the coupler. Electrical continuity shall be ensured by
tightening up a hexagon locknut against the coupler. Any exposed threads on either conduit shall be painted with at least two coats of antirust paint.


8 Provision of Adaptable Box

An adequate number of suitably sized adaptable boxes shall be provided in all conduit runs to enable cables to be drawn in and out easily without damage. Adaptable boxes shall be provided immediately after every two bends, or after a bend plus a maximum straight run of 10m, or after
a maximum straight run of 15m.


9 Spacing between Conduits

Adjacent or parallel conduits cast in concrete shall be separated by a spacing of not less than 25mm so as to allow concrete aggregate to pass and set between them.


10 Termination of Conduits at Metal Casing of Equipment

Where a steel conduit terminates at a metal casing, a coupler and a brass male bush shall be used. The brass male bush shall be screwed into the coupler or adaptor from the inside of the metal casing through a clearance hole drilled in the metal casing to suit the bush. Both the conduit and the bush shall be screwed tightly into the coupler or adaptor so as to grip the metal casing securely for mechanical and electrical continuity.

Threads on the steel conduit shall be at least half the coupler length. Connection between flexible conduit and the adaptor shall be securely fixed. No threads on the metal casing shall be allowed. In the case of flexible steel conduit, a brass adaptor together with a brass male bush shall be used. The brass adaptor shall comprise two parts, an inner core and an outer ferrule. The inner core shall screw into the bore of the conduit together with an outer ferrule which caps off the
end of the conduit, so that the adaptor can provide an extremely strong joint. The core shall lock against the outer ferrule and isolate any sharp cut edges in the conduit.

Where a metal casing is painted or enamelled, the electrical continuity between the conduit and the casing shall be achieved by means of a separate circuit protective conductor connecting the conduit and an earth terminal of the casing. Alternatively, a copper continuity connector may be placed between the bush and the metal casing. The cross-sectional area of the separate circuit protective conductor or the copper continuity connector shall have the same current carrying capacity as the largest live conductor drawn into the conduit in accordance with the IEC 60364. Neither the paint nor the enamel shall be damaged or removed in order to achieve the electrical continuity.


11 Conduit Bend

Conduit shall not be bent with an acute angle. The internal radius of the bend shall not be less than 2.5 times the outside diameter of the conduit.


12 Conduit Crossing Expansion Joint

Where a steel conduit crosses an expansion joint, special arrangement shall be made to allow relative movement to occur on either side of the expansion joint. A separate circuit protective conductor shall be installed to maintain an effective electrical continuity across the expansion joint. The circuit protective conductor shall have a crosssectional area rated to suit the largest live conductor drawn into the conduit in accordance with IEC 60364.


13 Use of Extension Ring

An extension ring shall be fitted to a conduit box where the plaster wall finish (including plaster) is more than 35mm from the conduit box. Only extension rings of the correct depth shall be used. Under no circumstances shall multiple extension rings be permitted.


14 Prevention of Ingress of Foreign Matters

During the building construction, all open ends of the conduit termination, which are liable to be filled with water, moisture or other foreign matters, shall be plugged with approved conduit stopping plugs;
paper, rag or similar materials shall NOT be used for this purpose. Steel conduit boxes in similar circumstances shall also be similarly plugged to prevent concrete aggregate or plaster from entering into the boxes during building construction.


15 Prevention of Accumulation of Water or Moisture

The conduits shall be so laid to prevent accumulation of condensed moisture and the ingress of water in any part of the installation. Approved type of sealant for the prevention of condensed moisture shall be applied to ceiling conduit outlets installed in a cooled space subject to the influx of warm air.


16 Conduit Laid Direct in Ground

Steel conduits laid direct in ground or buried in soil shall be painted with two coats of bituminous paint and wrapped with selfamalgamating tapes or other wrapping materials for protection against
corrosion and approved by the Architect.


17 Fixing of Distance (Spacing) Saddle

Saddles, for the support of surface conduits, shall be provided throughout the entire route at regular intervals. The spacing between adjacent saddles for steel conduits shall not be more than those. Each bend of a surface conduit shall be supported by a saddle on either side of the bend, and the saddles shall be fixed as near to the bend as practicable.
Saddles shall be fixed with brass screws in expanding plugs or other purpose-designed fixing devices approved by the Architect.


18 Conduit Installed Outdoors or in Damp Situation

Where steel conduits are installed outdoors or in damp situations, all conduit fittings and conduit accessories shall not be placed in contact with other metals with which they are liable to set up electrolytic action. In addition, where the conduit installation is subject to weather, the conduit fittings and conduit accessories shall be provided with weatherproof sealant or other materials to ensure that the installation is completely weatherproof.


19 Swabbing Out of Conduit

Conduits shall be swabbed out and free from moisture before wiring work is to commence. The swabbing operation shall be witnessed by the authorised representative of the Architect. Only approved draw-in tape or steel wire of appropriate size and absorbent cloth shall be used.


20 Fire Barrier

Where a conduit passes through fire resistant structural elements, such as walls and floors designated as fire barriers, the opening made shall be sealed according to the appropriate degree of fire resistance of the wall and/or floor. In addition, where a conduit is installed in a channel, duct,
ducting, trunking or shaft which pass through such elements, suitable fire-resistant barriers shall also be provided to prevent the spread of fire.


21 Identification

Conduits, where required to be distinguished from pipelines or other services, shall use orange (BS colour reference No. 06 E 51 to BS 4800) as the basic identification colour in compliance with BS 1710.


22 Cable Capacity of Conduit

The number of cables drawn into a conduit shall be such that no damage will be caused to the cables or to the conduits during their installation.
In determining the size of the conduit, the “unit system” method shall be adopted.


23 Method of Drawing Cables into Conduit

Conduit system shall be completely erected before cable is drawn in and there shall be adequate means of access for drawing cable in or out. Cables shall be drawn into a conduit by using approved draw-in tape or steel wire of the appropriate size. Under no circumstances shall the use of lubricants, e.g. grease, graphite, talc power, etc., be permitted to assist in the drawing the cables.


24 Segregation of Cables of Different Circuit Categories

Separate conduits shall be provided for cables of different circuit
categories or using different voltage levels.


25 “Looping-in” Wiring System

Each cable in a run shall be of one continuous length and wired on the
“loop-in” system. No joint in cable run shall be allowed.


26 Grouping of Cables in Conduit

Conduits running from a distribution board to the final distribution point may each contain all live conductors of a number of final circuits provided that the effective current-carrying capacity of all circuits, upon taking the correction factors into consideration, shall exceed the rating of their respective over-current protection devices and all conditions as stipulated in Sub-section 22 above are satisfied.
For conduits serving final circuits direct from a distribution board or from an adaptable box used as a final distribution point, each conduit shall contain all live cables of one final circuit only except in the case of lighting final circuit where two circuits with 1.0mm2 or 1.5mm2 cables will be permitted in a 20mm diameter conduit.
The neutral cable of a lighting final circuit using single core cables may be routed in the conduit direct to the lighting point without passing through the switch box.


27 Termination of Bonding Conductors at Conduit Installation

For surface conduit installations, the supplementary bonding conductors shall be terminated at the nearest conduit or conduit box forming an integral part of the conduit installation.
For concealed conduit installations, the supplementary bonding conductors shall be terminated at a copper earthing terminal fitted inside a metal box forming an integral part of the conduit installation. The metal conduit box shall be located as near as possible to the bonding position and the exposed part of the supplementary bonding conductor shall be made as short as possible.

Electrical Safety Glosary - 01

Ampere (amps)
A measure of electrical cur­rent flow.

Arc-Fault Circuit Interrupter (AFCI)
Provides protection from fires caused by effects of elec­trical arcing in wiring. An AFCI device will de-energize the circuit when an arc fault is detected.

Circuit
The path (usually wire) through which current flows between an electrical en­ergy source and an electrical device, appliance or fixture.

Circuit breaker or Fuses
Protect against over­current and short circuit conditions that could result in potential fire hazards by opening a circuit path in case of an overcurrent.

Electrical faults
A partial or total failure in an electrical conductor or appliance.

Energized
Electrically connected to a source of potential difference, or electrically charged so as to have a potential different from that of the ground.

Gauge
Standard or scale of measure for cir­cuit conductors.

Ground
Fault Circuit Interrupter (GFCI)—Pro­vides the best available protection against se­vere shock and electrocution. A GFCI device will de-energize a circuit when it senses a dif­ference in the amount of electricity passing through the device and returning through the device, or a “leak” of current from the circuit.

Grounded/grounding
A conducting con­nection, whether intentional or accidental, by which an electric circuit or equipment is connected to the earth, or to some conduct­ing body of relatively large extent that serves in place of the earth.

Overcurrent
Any current in excess of the rated current or ampacity of a conductor. May result in risk of fire or shock from insulation damaged from heat generated by overcurrent condition.

Outlet
A contact device installed along a cir­cuit for the connection of an attachment plug and flexible cord to supply power to portable equipment and electrical appliances. Also known as receptacles.

Three-pronged plugs and outlets
Grounded appliances and outlets (unless marked other­wise) have a third socket or prong. The third wire, or grounding conductor, provides a path from the frame or housing of grounded electri­cal appliances back to the circuit breaker panel to permit current flow in event of an electrical fault in the equipment. When a ground fault occurs, the circuit breaker can trip to remove
energy from the faulty equipment but does not respond quickly enough to prevent the risk of severe shock.

Short circuit
An abnormal electrical path.

Voltage (volts)
A measure of electrical po­tential

Wattage (watts)
A measure of power or the rate of energy consumption by an electrical device when it is in operation, calculated by multiplying the voltage at which an appliance operates by the current it draws (Watts = Volts X Amperes).

Electrical Safety—The Checklist : New Protection

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New Protection—Arc Fault Circuit Interrupters (AFCIs)


Newer arc fault circuit interrupters (AFCIs) can help prevent fires that often result from problems at the outlets, switches and frayed and cracked cords connected to the circuits. The AFCI senses the particular signature of an arc—where electricity has to jump through an insulating medium—and, like the GFCI, acts immediately to shut off the circuit, thus reduc­ing the risk of fire associated with arcing faults.

AFCIs are currently required by the Na­tional Electrical Code® in new construction in all bedroom circuits, but should be consid­ered in all homes and all general purpose re­ceptacles. Consult a qualified, licensed electri­cian to determine if your home is compatible with AFCI protection.


Other technology

Over the years, we have begun to safety engi­neer our electrical products to include some of the same technology that has been applied to our electrical systems. Immersion detec­tion circuit interrupters (IDCIs) and appli­ance leakage current interrupters (ALCIs) are typically found on hair dryer and specific appliance cords.

They operate in slightly dif­ferent ways but perform essentially the same function. Leakage current detection interrupt­ers (LCDIs) are protective devices that help prevent fires due to damage to cords. They are presently being built into the plug cap of room air conditioners. If the cord is damaged, the LCDI circuitry detects an abnormal condi­tion and immediately shuts off power. LCDI technology is also available in select extension cords and power strips.


Batteries

When used correctly, batteries provide a safe and dependable source of power. However, if they are misused or abused, overheating, leak­age, or in extreme cases explosion or fire, can occur. Follow these safety principles when us­ing batteries:

• Always follow warnings and manufactur­ers instructions for both the batteries and the battery-operated product. Use only the correct type and size battery indicated.
• Check the contacts of both the battery and the battery-operated product for cleanli­ness.
• Always insert the batteries correctly with regard to polarity (-/+), matching the pos­itive and negative symbols of both battery and product. Putting them in backwards, the product will sometimes still operate, but may inadvertently charge the batteries resulting in venting or leaking.
• Remove and safely dispose of exhausted batteries immediately.
• Replace all batteries in battery-operated products at the same time and with the batteries of the same type and manufac­ture.
• Do not short circuit batteries. When the positive (+) and negative (-) terminals of a battery are in contact with each other, the battery can become short circuited. For example, loose batteries in a pocket with keys or coins can be short circuited possi­bly resulting in venting or explosion.
• Do not heat batteries.
• Do not crush, puncture, dismantle or oth­erwise damage batteries.
• Do not charge non-rechargeable batteries.
• Keep batteries out of reach of small chil­dren.
  

Electrical Safety—The Checklist : Test and Protect!

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Test and Protect!—Ground Fault Circuit Interrupters (GFCIs)

Ground fault circuit interrupters (GFCIs)—which protect against accidental electric shock or electrocution by acting immediately to shut off the circuit if they sense a ground fault, or “leak” of current off the circuit—have been in homes since the early 70s on circuits that come within six feet of water. Homeowners, however, should consider having GFCI protec­tion on general purpose receptacles through­out the home.

• There are outlet GFCIs protecting every­thing in that outlet and downstream on the circuit, circuit breaker GFCIs protect­ing the entire circuit, or portable GFCIs that protect just at the point of use.
  
  A GFCI-protected outlet can provide power without giving an indication that it is no lon­ger providing shock protection. Be sure your GFCI is providing protection from fatal elec­tric shock by testing it monthly and after every major electrical storm.
  
  
• You should test your GFCIs monthly and after every major electrical storm. Here’s how:
  
  
  # Push the “Reset” button of the GFCI receptacle to prepare the unit for testing.
  # Plug in a night light and turn it on. Light should be ON.
  # Push the “Test” button of the GFCI receptacle. Light should go OFF.
  # Push the “Reset” button again. Light should go ON.
  
  
  A light plugged into the GFCI receptacle should go out when the test button is pushed. If the light remains on when the button is pushed, either the GFCI is not working prop­erly or has not been correctly installed. If the “RESET” button pops out but the light does not go out, the GFCI has been damaged or was improperly wired and does not offer shock protection at that wall outlet. Contact a quali­fied electrician to correct any wiring errors or replace defective GFCIs.
  
• If you have a home without GFCIs, con­sult a qualified, licensed electrician about adding this important protection, or pur­chase plug-in units or a portable GFCI to provide individual receptacle or load pro­tection.
  

Electrical Safety—The Checklist : Small Appliances and Tools

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Small Appliances and Tools

Follow these simple safety precautions with all your small appliances and tools:

• Make certain all small appliances and tools are approved by an independent testing laboratory, such as Underwriters Laboratories (UL), ETL-SEMKO (ETL) or Canadian Standards Association (CSA). (See example on page 18.)
• Use small appliances and power tools according to the manufacturer’s instruc­tions.
• Unplug all small electrical appliances, such as hair dryers, shavers, curling irons, clothes irons, and toasters, when not in use.
• Be sure you have ground fault circuit inter­rupter (GFCI) protection anywhere elec­tricity and water are within six feet of each other, such as in your kitchen, bathroom and outdoors, to protect against electric shock. For more information, see the sec­tion on GFCIs, page 25.
• Take any damaged electrical appliance or tool to an authorized repair center, or cut the cord, safely dispose of the item, and purchase a new one.
  
  Tips : Even an appliance that is not turned on, such as a hairdryer, can be potentially hazardous if it is left plugged in. If it falls into water in a sink or bathtub while plugged in, it can electrocute you. New hair dryers should always have a safety device called an appliance leakage circuit interrupter (ALCI) on their power cords to protect against electrocution.
  
  
• Never reach into water to get an appliance that has fallen in without being sure the appliance is unplugged or the circuit is shut off.
• Never reach into water to get an appliance that has fallen in without being sure the appliance is unplugged or the circuit is shut off.
  
  
  Tips : “Tucking in” an electric blanket or placing additional coverings on top of it can cause excessive heat buildup, which can start a fire.
  
  
• Do not tuck in electric blankets.
• Don’t allow anything on top of the blan­ket while it is in use. This includes other blankets or comforters and even pets sleeping on top of the blanket.
• Do not use electric blankets on children.
• Never go to sleep with a heating pad that is turned on. It can burn you. Newer heating pads have an automatic cut off switch.
  
  Tips : Sleeping with a heating pad that is turned on can cause serious burns even at relatively low settings.
  
• Check to make sure power tools have a 3-prong plug or double-insulated cords, and consider replacing old tools that have neither.
• Use a properly grounded 3-prong adapter for connecting a 3-prong to a 2-hole re­ceptacle.
• Consider using a portable GFCI when us­ing power tools.
• Replace guards that have been removed from power tools.
• There have been many recalls of power tools due to problems with the safety guard sticking. Be sure your model has not been recalled, as this hazard poses a serious risk of injury.
• Check power tools before each use for frayed cords, broken plugs or cracked housing.

Electrical Safety—The Checklist : Portable Space Heaters

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Portable Space Heaters

Portable space heaters can be a blessing in a cold and drafty house in the deep of winter. But space heaters, and any electrical product with a heating element, can demand a lot of power. By their nature, they also produce a lot of heat, and, if not used carefully, can become a fire hazard. Make sure to follow these safety principles with portable space heaters:

• Plug portable space heaters directly into an outlet; do not use an extension cord.
• Make certain the circuit into which you plug a space heater can adequately and safely handle the added demand.
• Never remove the grounding feature on a plug by clipping or grinding off the third prong.
• Use an adapter to connect the heater’s 3-prong plug, if you do not have a 3-hole outlet. Make sure the adapter ground wire or tab is attached to the outlet ground.
• Relocate heaters away from passageways and keep all flammable materials such as curtains, rugs, furniture or newspaper at least three feet away.
• Unplug and safely store portable space heaters when not in use.Plug portable space heaters directly into an outlet; do not use an extension cord.

Electrical Safety—The Checklist : Light Bulbs

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Light Bulbs

We’ve come to take the light bulb for grant­ed, but there is a wide variety of bulbs avail­able that provide different levels and quality of light, and that demand different levels of power. Make sure you are selecting the bulbs that are appropriate for your intended use and for the power rating of the intended lamp or fixture.

• Use a bulb of the correct type and watt­age. If you do not know the correct watt­age, contact the manufacturer of the lamp or fixture.
• Read and follow light bulb manufacturers’ safety instructions.
• Make sure bulbs are screwed in securely —loose bulbs may overheat.
• Place halogen floor lamps (torchieres) away from curtains, beds, rugs or other furnishings. These lamps can become very hot and can cause a fire hazard. Consider replacing halogen torchiere lamps with models that use cooler, more efficient flu­orescent bulbs.

A bulb of too high wattage or of the wrong type may lead to fire through overheating. Some ceiling fixtures and recessed lights can trap heat.

Electrical Safety—The Checklist : Surge Protection

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Power strips and surge protection

Power strips give us the ability to plug more products into the same outlet, which can be a help, but also a hindrance to safety if used in­appropriately. Power strips and surge suppres­sors don’t provide more power to a location, just more access to the same limited capacity of the circuit into which it is connected.

The circuit likely also still serves a variety of other outlets and fixtures in addition to the multiple electrical items you might be supplying with the power strip. In addition to the tips above, keep these safety principles in mind when us­ing power strips and surge suppressors.

• Be sure you are not overloading the circuit. Know capacity of the circuit and the pow­er requirements of all the electrical items plugged into the power strip and into all the other outlets on the circuit as well as the light fixtures on the circuit.
• A heavy reliance power strips is an indica­tion that you have too few outlets to ad­dress your needs. Have additional outlets installed where you need them.
• Understand that surge suppressors only protect the items plugged into it, not back along the circuit into which it is con­nected.
• In the event of a large surge or spike, such as a lightning strike, the surge suppressor is a one-time-use protector and will likely have to be replaced.
• Consider purchasing surge suppressors with cable and phone jacks to provide the same protection to your phone, fax, com­puter modem and television.
• Not all power strips are surge suppressors, not all surge suppressors can handle the same load and events. Be sure the equip­ment you buy matches your needs.
• For homes in areas with a high incidence of lightning, consider having a surge ar­restor installed at the fuse box or breaker panel for whole house protection

Electrical Safety—The Checklist : Extension Cords

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Extension Cords

Extension cords can be very helpful in deliver­ing power right where we need it. However, no matter what the gauge or rating of the cord is, the extension cord is designed as a temporary solution, not as long-term extension of your household’s electrical system. With continu­ous use, the extension cord can more rapidly deteriorate, creating a potentially dangerous electric shock or fire hazard. In addition to the same safety tips that apply to power cords, keep the following principles in mind when using extension cords.

• Extension cords should only be used on a temporary basis; they are not in­tended as permanent household wiring. Unplug and safely store extension cords after every use.
• A heavy reliance on extension cords is an indication that you have too few outlets to address your needs. Have additional out­lets installed where you need them.
• Make sure extension cords are properly rated for their intended use, indoor or outdoor, and meet or exceed the pow­er needs of the appliance or tool being plugged into it.
• Assume 125W per amp when calculating power (wattage) to determine if the exten­sion cord you intend to use is properly rat­ed for the appliance being connected to it.
• Replace No. 18 gauge cords with No. 16 gauge cords. Older extension cords using small (No. 18 gauge) wires will overheat at 15 amps or 20 amps.
• Change the cord to a higher rated one or unplug some appliances, if the rating on the cord is exceeded because of the power requirements of one or more appliances being used on the cord.
  
  
  Tips : Overloaded extension cords can and do cause fires.
  
  
• Use cords with polarized and/or three-prong plugs.
• Buy only cords approved by an indepen­dent testing laboratory, such as Underwrit­ers Laboratories (UL), ETL-SEMKO (ETL) or Canadian Standards Association (CSA).

Electrical Safety—The Checklist : Power Cords

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Power Cords

Power cords, part of electrical products and appliances, connect the item to the power sup­ply by plugging into the outlet. They need to be kept in good condition. Even an electrical item that is in otherwise good working order can still represent a shock and fire hazard if its power cord is damaged.

• Check to make sure electrical cords are in­tact and in good condition, not frayed or cracked.
• Check to make sure lamp, extension, tele­phone and other cords are placed out of the flow of traffic. Cords stretched across walkways may cause someone to trip. If you must use an extension cord, place it on the floor against a wall where people cannot trip over it.
• Whenever possible, arrange furniture so that outlets are available for lamps, enter­tainment products, or appliances without the use of extension cords.
• Check to make sure furniture is not rest­ing on cords.
• Check to make sure electrical cords do not run under furniture or carpeting, or behind baseboards.
• Check to make sure electrical cords are not attached to the walls, baseboards, etc. with nails or staples. Disconnect power before removing nails and staples from on or around electrical cords.
• Do not attempt to repair cords yourself. Take any item with a damaged power cord to an authorized repair center, or cut the cord, safely dispose of the item, and pur­chase a new one.

Tips : Cutting off the cord when disposing of a damaged electrical product reduces the likelihood of someone else “salvaging” the item and bringing the hazard home with them.

Electrical Safety—The Checklist : Fuses

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Fuses

Replacing a correct size fuse with a larger size fuse can present a serious fire hazard. Doing so will allow excessive current to flow and pos­sibly overload the outlet and the house wiring to the point that a fire can begin.

• Be certain that correct-size fuses are used (if you do not know the correct sizes, have a qualified, licensed electrician identify and label the sizes to be used).

NOTE: Fuses should be rated according to the wire that makes up the branch circuit, not the connected load. Most of the screw-based fuses used should be 15 amperes. Ensure that all fuses rated higher than 15 amperes are compatible with the branch circuit wiring.


Edison-base/S-type Fuses

Consumers sometimes replace a fuse that re­peatedly “blows” with a higher ampere rated fuse. Although the new fuse may not open, it also may not protect the branch circuit. Do­ing so masks the real problem of too high a demand being placed on the circuit. The fuse will not open at the appropriate load for that circuit.


Instead of using an inappropriate fuse, take something off the circuit to bring the de­mand to an appropriate level.

• To prevent future installation of fuses that allow currents too high for your wiring, your fuse panel should be converted to S-type sockets that accept only fuses of the correct amperage rating. If you have Edison-base fuse sockets, have them fitted with the S-type socket inserts.

If fuses continue to “blow,” keep track of which branch circuits are affected and which appliances are in use when the power outage occurs. Consult a qualified, licensed electri­cian to correct the problem.

Electrical Safety—The Checklist : Fuses/ Circuit Breaker

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With your circuit map and power audit done, it’s time to take a run through the house with a keen eye on safety. Use the following checklist on a regular basis to en­sure your home remains electrically safe year in and year out. If you haven’t already had an electrical inspection performed by a qualified, licensed electrician or electrical inspector, this list can also help identify clues that an inspec­tion and/or repairs are needed.


Fuses/Circuit Breakers

Fuses and circuit breakers are safety devices lo­cated in your electrical panel that help prevent overloading and fires.

They stop the electrical current if it exceeds the safe level for some por­tion of the home electrical system. Overload­ing means that the appliances and lighting on the circuit regularly demand more electrical current than the circuit can safely deliver.

If the demand for electrical current ex­ceeds the safety level, a fuse opens once and must be replaced to reconnect the circuit. A cir­cuit breaker “trips” its switch to open the cir­cuit, and the circuit is reconnected by closing the switch manually.