UL 38:2008 pdf download.Manual Signaling Boxes for Fire Alarm Systems.
3.4 Nonmetallic enclosures
3.4.1 An enclosure or parts of an enclosure of nonmetallic material shall have the mechanical strength and durability and be formed so that operating parts will be protected against damage. The mechanical strength of the enclosure shall be at least equivalent to a sheet metal enclosure of the minimum thickness specified in Table 3.2. See the Impact Test for Enclosures, Section 27, and the Polymeric Materials Test, Section 28.
3.4.2 Among the factors to be taken into consideration when determining the acceptability of a nonmetallic enclosure or parts are:
a) The mechanical strength:
b) Resistance to impact;
c) Moisture absorptive properties;
d) Combustibility and resistance to ignition from electrical sources:
e) Dielectric strength, insulation resistance, and resistance to arc tracking; and
f) Resistance to distortion and creeping at temperatures to which the material may be subØcted under conditions of normal or abnormal usage.
All these factors are to be considered with regard to aging.
3.4.3 The continuity of the grounding system shall not rely on the dimensional integrity of the nonmetallic material.
4 Electric Shock
4.1 Any part that is exposed only during operator servicing shall not present the risk of electric shock. See the Electric Shock Current Test, Section 21.
4.2 Each terminal provided for the connection of an external antenna shall be conductively connected to the supply circuit grounded conductor. The conductive connection shall have a maximum resistance of 5.2 megohms, a minimum wattage rating of 1/2 watt, and shall be effective with the power switch in either the on or off position.
3.4.1 An enclosure or parts of an enclosure of nonmetallic material shall have the mechanical strength and durability and be formed so that operating parts will be protected against damage. The mechanical strength of the enclosure shall be at least equivalent to a sheet metal enclosure of the minimum thickness specified in Table 3.2. See the Impact Test for Enclosures, Section 27, and the Polymeric Materials Test, Section 28.
3.4.2 Among the factors to be taken into consideration when determining the acceptability of a nonmetallic enclosure or parts are:
a) The mechanical strength:
b) Resistance to impact;
c) Moisture absorptive properties;
d) Combustibility and resistance to ignition from electrical sources:
e) Dielectric strength, insulation resistance, and resistance to arc tracking; and
f) Resistance to distortion and creeping at temperatures to which the material may be subØcted under conditions of normal or abnormal usage.
All these factors are to be considered with regard to aging.
3.4.3 The continuity of the grounding system shall not rely on the dimensional integrity of the nonmetallic material.
4 Electric Shock
4.1 Any part that is exposed only during operator servicing shall not present the risk of electric shock. See the Electric Shock Current Test, Section 21.
4.2 Each terminal provided for the connection of an external antenna shall be conductively connected to the supply circuit grounded conductor. The conductive connection shall have a maximum resistance of 5.2 megohms, a minimum wattage rating of 1/2 watt, and shall be effective with the power switch in either the on or off position.
