Please note: All interim revisions for this edition available at time of your purchase will be included.

Electric Space Heating Cables

UL 1673

1 Scope

1.1 These requirements cover electric space heating cables intended for space heating purposes, rated for 480 V or less, for installation in unclassified locations in accordance with Article 424 Part V of the National Electrical Code (NEC), ANSI/NFPA 70.

1.1 revised October 14, 2011

1.2 These requirements apply to space heating cables intended for installation in ceilings of enclosed structures or within or beneath floors of enclosed structures where the floor is constructed of noncombustible material, concrete, or asphalt.

1.3 These requirements do not cover electric heating equipment or appliances that are covered by individual requirements that are separate from this Standard. Other related standards include:

a) Electrical Resistance Heat Tracing for Commercial and Industrial Applications, UL 515;

b) Movable and Wall- or Ceiling-Hung Electric Room Heaters,UL 1278;

c) Outline of Investigation for Mobile Home Pipe Heating Cables, Subject 1462;

d) Outline of Investigation for Roof and Gutter De-Icing Cable Units, Subject 1588;

e) Electric Radiant Heating Panels and Heating Panel Sets, UL 1693;

f) Outline of Investigation for Residential Pipe Heating Cables, Subject 2049;

g) Fixed and Location-Dedicated Electric Room Heaters, UL 2021; and

h) Electric Heating Appliances, UL 499.

1.3 revised October 14, 2011

1.4 These requirements do not cover the following:

a) Heating cable intended to be installed in a dropped or suspended ceiling;

b) Heating cable connected to the supply by use of a flexible cord with attachment plug;

c) Heating cable equipment that is movable after installation;

d) Heating equipment with integral means of producing air flow;

e) Heating equipment manufactured and sold as an integral part of a floor covering materials such as heated floor tiles, heated carpet, and heated laminate floor;

f) Heating equipment intended for installation on dry board or plaster, when heating equipment exceeds 2-3/4 W/ft (9 W/m) and/or with adjacent runs intended to be installed less than 1.5 inches (38 mm) on center;

g) Constant wattage heating cable intended for installation in concrete or poured masonry floors with heating leads rated greater than 16-1/2 W/ft (54 W/m); and

h) Heating panels and panel sets of Article Part IX of the National Electrical Code (NEC), ANSI/NFPA 70; and

i) Heating cables for installation directly below floor coverings in accordance with 424.99 of the National Electrical Code (NEC), ANSI/NFPA 70.

1.4 revised October 14, 2011

1.5 These requirements do not cover switches, transformers, power supplies, controls (e.g. temperature) or protective devices (e.g. ground fault protection) that are typically installed separate from the space heating cable but may be installed at the same time as part of the space heating system. Those devices are covered by individual requirements that are separate from this Standard.

1.5 revised October 14, 2011