Electrical Fire Risk Seen In Improper Use of Insulation

Electrical Fire Risk Seen In Improper Use of Insulation

Energy conservation programs being advocated throughout the country can have a profound effect on electrical wiring and equipment. This was the opinion of the electricity committee of the New York Board of Fire Underwriters.

According to the report, many dwellings will have additional insulation and this may create problems for electrical equipment. Insulation around conductors could cause an increase in their normal operating temperatures by filling the voids so that there is no space for the release of normal heat. Temperatures, therefore, could reach the ignition point.

Underwriters Laboratories tests indicate that where the conductors are carrying up to 80 percent of their capacity, excessive temperatures are not reached even with the most efficient foam insulations. However, where the current flow is 100 percent of capacity, excessive temperatures may be developed if the space through which the conductors run is insulated.

With the increased use of electricity, especially in older homes, the committee found it probable that the conductors are operating at full capacity and, in some cases, to overcapacity by the installation of oversized fuses or circuit breakers. Under these conditions, the encasement of the conductors with additional insulation could create fire conditions.

Many recommendations have been set forth to minimize this hazard. The only feasible one, the report said, is the installation of additional electrical circuits to better distribute the electrical load. Such a program would ensure that high-current-consuming appliances such as air conditioners, heaters and dryers, are supplied by separate circuits.

There are other hazardous conditions in electrical installations and insulation that must be recognized. For instance, the ventilation for recessed electrical lighting fixtures should not be obstructed by added insulation. Care must be taken that foamed-type insulation does not penetrate electrical boxes or units where they might cause overheating or corrosion of the equipment because of leaching of fireproofing salts.

There may also be some unusual equipment coming on the market for which there is no past experience. This may include heat-saving devices, solar heating units and supplemental heating units, all of which will require electrical wiring and will require close supervision to make sure that they do not bypass safeguards presently installed.

The committee warned that the following five hazards must be guarded against:

  1. Overheating during operation of electrical equipment.
  2. Overheating due to exothermic heat liberation during curing of some types of insulating materials.
  3. Chemical interaction of electrical and thermal insulating materials.
  4. Chemically induced corrosion of normal current carrying and grounding conductors, terminals, and fittings.
  5. Increased difficulties of rewiring after some types of thermal insulating materials are installed.

The committee believes it essential that the installation of energy-conserving methods and devices be coordinated with present electrical equipment to avoid hazards.

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