PREVALENCIA DE LA AN

A. The construction of the appliance shall assure that normal use and user servicing does not result in a shock, casualty of fire hazard; that the materials and components are used within their electrical, mechanical and temperature limits, and that the assembly will protect the components and wirings from being displaced or damaged.

B. Cellulose nitrate or any comparably flammable material shall not be used for a cabinet, cabinet-covering material, dial, window or similar part.

C. Material for the mounting of uninsulated line parts that involved a power of 50 watts or more shall be flame-retardant or self-extinguishing. Components involved are connectors, printed wiring, boards, terminal strips, tube and transistor sockets, deflection yoke, coil forms etc.

D. Recording disc or tape shall not be formed or coated with cellulose nitrate or comparable flammable material and the hazards of storing the disc, tapes, etc. shall not be greater than those presented by common newsprint in the same general form and quality.

E. A spacing of 13 mm. minimum over surfaces or through air shall be maintained between uninsulated live parts of the supply circuit and (1) line parts of opposite polarity and (2) accessible metal parts; except when the location and relative arrangement of the parts are such that adequate is assured.

F. Except for insulation built into a component, a barrier or liner of fiber or similar material employed where spacing would otherwise be insufficient between uninsulated line parts of opposite polarity or between such parts and exposed or partially protected metal parts, shall be 1 mm. thick minimum. A barrier or liner used in conjunction with an air spacing may be 0.5 mm. thick minimum provided it is (1) a suitable insulating material, (2) resistant to moisture, (3) of adequate mechanical strength if liable to mechanical injury, (4) reliably held in place and (5) located so that it will not be affected adversely by operating the appliance.

G. Unless an acceptable barrier is provided, there shall be a spacing through air of 3 mm. minimum between the uninsulated live parts of a fuse and fuse clip and (1) uninsulated live parts of opposite polarity, and (2) the chassis or metal in electrical connection with the chassis. The spacing shall be determined with the fuse in place.

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H. If shock hazard results from an electrical connection between the external conductive coating of the picture tube, and the picture tube mounting means (straps, brackets, etc.) that contact the tube, there shall be a spacing of 13 mm. minimum between the conductive coating and the mounting means. The spacing shall be measured over the surface of the tube.

I. Casualty hazard is considered to exist if moving parts such as gears and linkages are accessible during normal operation. Exceptions are moving parts that are accessible only through the bottom or underside of console/chair type enclosure or drawer is located not more than 15 cm. above the floor and the moving parts are excessed at least 7.5 cm. from the front edge and side of the enclosure or drawer.

J. Fire hazard is considered to exist at any component connected across a supply circuit, either under normal conditions or when the chassis and all user connections are grounded while the power supply rectifier and any two elements of one other vacuum tube, transistor or similar solid state device are short-circuited, unless one or more of the following condition exist;

a) there is additional series impedance of not less than 10,000 ohms, exclusive of any adjustable or variable air dielectric capacitor in a circuit when the voltage is 125 volts or less.

b) there is additional series impedance of not less than 20,000 ohms, exclusive of any adjustable or variable air-dielectric capacitor in a circuit where the voltage is more than 125 volts but not more than 250 volts.

c) combustible material such as surgical cotton shall not be ignited under any service conditions of breakdown or failure of the part itself.

K. To be free from fire hazard, the source of power for a component part or assembly shall not be capable of delivering a power of more than 15 watts into an external resistor connected between any two points on the assembly with all components in place and:

a) if the source of power is directly from the secondary winding of an isolating type transformer the conditions of loading to maximum power and of short circuiting the secondary winding shall not produce a fire or shock hazard.

b) if the source of power employs a resistor to limit the power to 15 watts or less, any conditions of loading to maximum power or short circuiting the points in question shall not cause the resistor to change value to the extent that the 15-watt limit will be exceeded.

c) the short or open circuiting (singly) of any rectifier, vacuum tube, transistor, or electrolytic capacitor between the 15-watt point and the power supply circuit shall not cause the 15-watt limit be exceeded.

d) an isolating type of transformer shall be capable of withstanding without breakdown for a period of 1 minute, a 900 volts AC at 60 Hertz between (1) any live-metal part conductively connected to the supply circuit and any dead metal parts and (2) any live or current carrying part of the primary power supply circuit and only live or current-carrying part of the secondary circuit.

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L. Shock hazard shall be considered to exist at an accessible part in a circuit when one or more of the following conditions exist:

a) If the current through a load of not less than 500 ohms exceeds 300 milliamperes after 0.0003 second;

b) If the current through a load of not less than 500 ohms exceeds 5 milliamperes after 0.2 seconds;

c) If the time required for the current through a load of not less than 500 ohms to decrease to 5 milliamperes is between 0.1 and 0.2 second, and the total quantity of electricity passed through the load up to that time exceeds 4 millicoulombs.

d) If the time required for the current through a load of not less than 500 ohms to decrease to 5 milliamperes is between 0.03 and 0.1 second and the total quantity of electricity passed through the load up to that time exceeds 75T – 350T² millicoulombs where T is the time in seconds.

e) If more than 30 milliamperes can be drawn through a load of 1500 ohms.

The current referred to above refers to the current that can be drawn through a load connected to the accessible part and floor, ground or any other exposed metal part within reach by an adult person (1.5 meters).

M. Any adjustable or variable air-dielectric capacitor and the heater-to-cathode insulation of vacuum tubes shall not be relied upon to eliminate shock hazard.

9.2.2 User-Servicing

User-Servicing includes the following:

A. Battery Replacement of a battery except one designed to be soldered in place.

B. Fuse Replacement of a fuse except:

1) one designed to be soldered in place.

2) one not readily perceptible by the user. A fuse is not readily perceptible if located within a chassis, compartment, or enclosure within the overall appliance that makes the fuse invisible to the user. If the enclosure has a cover, it is to be one that (a) does not need to be opened or removed in normal operation or user-servicing, (b) can be opened or removed only with a tool, (c) is prevented from being discarded. A fuse is readily perceptible if recognizable during normal operation or user-servicing either visually or by touch; or if the fuse is indicated either on the appliance or on literature packed with it.

3) a clipped-in type that is within a compartment provided with the marking described in Rule 10.7.10. (No User-Serviceable Parts Compartment Warning).

96 C. Pilot Lamp Replacement of a pilot lamp except:

1) One designed to be soldered in place.

2) a filament type lamp which (a) is rated at 28 volts or less,

(b) has an estimated life at the operating voltage or at the voltage resulting from failure of any one user serviceable component of not less than 20,000 hours for a lamp energized only while the appliance is “on”, and (c) is connected in a circuit in which the increased voltage incident to switching, user-servicing, or any operational characteristic of the appliance does not exceed 120 percent of the voltage recommended to provide the anticipated life required. Except for item (a), the serviceability of a gaseous-discharge-type lamp is determined in the same manner as for a filament-type lamp. Other types of lamps will be given special consideration with respect to the intent of the requirements.

3) A gaseous-discharge-type lamp under the conditions described for a filament-type lamp without limitation on voltage rating.

4) Any other type of lamp considered with respect to the intent of the requirements.

D. Picture Tube Replacement of a picture tube except:

1) A directly-viewed typed less than 15 cm. diameter maximum which obviously is not intended for replacement because it requires removal of rearrangement of major components such as chassis, printed wiring assembly, deflection yoke, etc.

2) Directly-viewed types having a maximum diameter of 15 cm. or more.

3) Projection type if house in separate enclosure making the tube inaccessible except by the use of a tool, and if the enclosure is marked in accordance with rule 10.1.14. (Projection-type Picture Tube Warning).

E. Vacuum Tube and Vibrator Replacement of a vacuum tube and vibrator except:

1) Tubes design to be soldered in place.

2) For an appliance employing vacuum tubes of the plug-in type, one tube and/or vibrator are not subject to user-servicing of the tube and/or vibrator are (a) located within the chassis, (b) not visible, (c) accessible only by use of a tool and (d) not marked on the appliance or on literature packed with it.

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F. Picture Tube and Window Cleaning The cleaning of a picture tube or windows, if access to the parts to be cleaned can be gained using ordinary tools and without removing the chassis or the picture tube from the cabinet. During the cleaning operation live parts are considered adequately protected if:

a) The front cover of a picture tube enclosure can be opened for cleaning or other user-servicing only after first opening an in interlock cover and if the warning described in Rule 10.7.12.

(Removable Front Cover Warning), is located on the cabinet where readily visible when the front cover is opened.

b) A barrier, such as a mask, that renders live parts inaccessible during removal or opening of a picture tube window, is (1) secured in a permanent manner, such as by nails, or (2) is secured independently of the window mounting, requires a tool for removal and is marked as required in Rule 10.7.1.3 (Picture Tube Window Barrier Warning).

9.2.3 Power Supply Connections

A. Power Supply Cord the power supply cord shall be in accordance with Table I. An equivalent or heavier type of cord may be used.

Table I

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B. The length of a power supply cord is to be measured from the face of the attachment-lug cap to the point where the cord emerges from the appliances.

C. Cord Connector Body a cord connector body employed as part of a separable cord set shall be so constructed that the cord-connector body cannot readily be used to defeat the conventional interlock device.

D. The conventional interlock device referred to above has nominally 2.5 mm. diameter pins, spaced 8 mm. apart, measured between pin centers.

E. Cord Strain Relief The power supply cord shall be attached to the appliances so that a mechanical strain on the cord leaving the overall enclosure will not:

a) Be transmitted to terminals, splices, interior wiring or;

b) Separate an interlock connector from the part of the appliance to which it is attached; or, c) Damage an interlock so that it does not perform its intended function.

F. Cord Push-Back Relief The power supply cord shall be provided with a knot or an equivalent stop which will prevent the cord from being pushed inside the chassis.

G. Cord Bearing Stress If a knot in a power-supply cord serves as strain relief, the surface against which the knot may bear or with which it may come in contact shall be free from projections, sharp edges, burrs, fins, which may cause abrasion of coverings on the conductors.

H. Cord and Wire Routing A separate flexible cord or wire which is not connected in the supply circuit or which does not involved shock or fire hazard shall not be routed through a bushing or opening with the power-supply cord.

I. Bushing Except as noted in Rules 9.2.3.J and 9.2.3.K, there shall be suitable insulating bushing, or the equivalent, which shall be substantial and reliably secured in a place where the power-supply cord emerges from the enclosure, and where the cord may be subjected to strain or motion.

J. An insulating bushing is not required with a Type SP-1 cord if the cord is built up with an additional 40 percent rubber jacket 0.8 mm. thick minimum at the point where it passes through the metal and if the hole through metal is free from sharp edges, burrs, fins, etc. a smooth metal bushing is acceptable if the Type SJ or heavier cord is used.

K. A smooth metal grommet is acceptable as a bushing in an enclosure other than metal, provided the inside diameter of the grommet is not less than 2.5 cm.

L. If the exit for the cord is in wood, porcelain, phenolic composition, or other suitable insulating material, a surface free of fins, burrs, and the like is considered to be equivalent of a bushing.

M. Ceramic materials and some molded compositions are considered acceptable for insulating bushings; but separate bushing of wood, rubber, and so-called hot-molded shellac, and tar compositions are not considered acceptable.

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N. Fiber may be employed if the finished bushing is 1.2 mm. thick minimum and if it is so formed and secured in place that it will not be affected adversely by conditions of ordinary moisture.

O. Polarized Appliance An appliance that is provided with a polarized attachment-plug cap of the two-wire parallel-blade type shall comply with the following:

a) An accessible part of the appliance shall not involve shock hazard.

b) There shall be no hazard with the attachment-plug cap inserted in the supply-circuit receptacle and then with supply-circuit connections reversed.

c) A switch, circuit breaker, fuse or other protective device shall not be connected in a circuit that is connected to the wide blade of the attachment-plug cap unless the component will simultaneously interrupt both conductors of the supply circuit.

d) The breakdown of a capacitor connected to an accessible metal part shall not cause the accessible part to involve shock hazard.

e) The screw or the equivalent of a lamp-holder shall not involve shock hazard when the lamp is accessible for servicing.

f) A polarized receptacle of the parallel-slot type mounted on the appliance shall have the identified (white) terminal connected to the wide blade of the attachment-plug cap.

g) In an interlock connector is mounted on a cover that can be applied as a complete enclosure in a normal manner but with the interlock connections reversed, the size, shape, or rearrangement of the contacts shall be such that the connection of the two interlocked parts can be affected only in one way.

h) Unless proper polarization is ensured by visual inspection and component checking, each complete appliance shall be treated, as a routine factory test, for electrical continuity between the wide blade of the attachment-plug cap and the part of the appliance circuit that is intended to be connected to the wide blade of the attachment-plug cap.

P. Except as required in Rule 9.2.3.O, the conductor of the supply circuit that is connected to the wide blade if the attachment-plug cap is considered to be at ground potential when evaluating shock hazard.

9.2.4 Wiring Devices

A. Mounting of Wiring Devices A switch, lamp holder, attachment-plug, or similar components shall be mounted securely except as noted in 9.2.4 B and 9.2.4 C.

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b) The means of mounting the switch make it unlikely that operation of the switch will loosen it.

c) The spacing‟s are not to be reduced below the minimum acceptable values if the switch rotates.

d) Normal operation of the switch is to be by mechanical means rather that by direct contact by persons.

C. A lamp holder of a type in which the lamp cannot be replaced, such as a neon pilot or indicator light in which the lamp is scaled in by a non-removable jewel, need not to be prevented from turning if rotation cannot reduce spacing‟s below the minimum acceptable values.

D. A lamp holder designed to be readily removable without the use of a tool need not to be prevented from turning.

E. The means for preventing the turning mentioned in Rule 9.2. .A is to consist of more than friction between surfaces e.g., if suitable lock washer, properly applied is acceptable as the means of preventing a small stem-mounted switch or other device having a single-hole mounting means from turning.

F. Unused Receptacle An unused receptacle, such as one provided for the attachment of an accessory, that involves hazardous energy shall not be of the type generally employed as a receptacle for a single prong, shielded-type phonograph plug, and if of the conventional parallel-type, shall involve line power only.

G. Receptacle Mounting Clearance If the face of a receptacle is less than mm. wide or less than 22 mm. long, the face of the receptacle shall project not more than 5 mm. from the part of the mounting surface that is within a rectangle 16 mm. wide and 22 mm. long symmetrically located about the receptacle contacts and if the mounting surface is conductive, the face of the receptacle shall project not less than 2.5 mm. from that part of the mounting surface.

H. Receptacle Insertion Clearance Except as noted in Rule . . .K the area surrounding an unused attachment-plug receptacle shall be free of any projections which would prevent full insertion of the blades of a circular attachment-plug cap having a face diameter of 30 mm. unless the projections are such that the blades of the attachment-plug are prevented from being inserted to make electrical contact with the female contacts of the receptacle.

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I. Clock-Radio Receptacle The area surrounding an unused clock-controlled attachment-plug receptacle in clock radios and the like shall be free of any projections which would prevent full insertion of the blades of a circular attachment-plug cap having a face diameter of 33 mm. and of a rectangular cap having a face of 38 mm. by 16 mm., unless the projections are such that the blades of the attachment-plug cap are prevented from being inserted to make electrical contact with the female contacts of the receptacle.

J. Lamp holder Construction The terminals of a lamp holder shall be securely riveted or otherwise secured in place. The center contact and its mounting shall be so secured that it will be held within the shell when the lamp is removed. The lamp holder terminals and other live parts, including the lamp base, shall be so protected that the possibility of grounding or of shock hazard, in use or while servicing, is remote. Soft rubber shall not be used for the insulation of lamp holder shells.

K. Switch Application A switch connected to wiring involving fire or shock hazard shall be suitable for the particular application.

L. Transfer Switch A transfer switch employed in a combination line and battery-operated appliance and involving shock hazard shall be so arranged that it cannot be accidentally operated.

M. Clock-Operated Receptacle Switch Enclosure Clock operated switch contacts controlling an

M. Clock-Operated Receptacle Switch Enclosure Clock operated switch contacts controlling an