A.  The total rating (or adjusted rating) of heat emission devices in each room or space to be heated must equal or exceed the calculated B.T.U. heat loss of such room or space, except that in bedrooms to be heated, a tolerance of not more than 20 percent less than the calculated B.T.U. required to offset the B.T.U. heat loss from such room will be allowed providing such deficiency is made up in other areas regarded as living area when computing the total calculated B.T.U. required for the dwelling.

B.  The total rating (or adjusted rating) of the heat emission devices must equal or exceed the calculated B.T.U. aggregate heat loss of all the rooms or spaces heated where used as living quarters.

C.  The output in B.T.U. of each heat generating and emission unit must be computed at the location where the electrical energy is converted to thermal (heat) energy. The conversion of electrical energy to thermal (heat) energy will be considered at an efficiency of 100 percent providing the labeled voltage of the equipment is within five percent of the service voltage. Where the labeled voltage of a heat generating or emission unit is greater or less than five percent of the service voltage, an adjusted rating of the heat generating or emission unit will be used in determining the B.T.U. output.

The adjusted B.T.U. rating =
3413 X (Service voltage)²
(Label voltage) 2 X KW name plate rating

B.  Cables may be installed in ceilings or poured masonry floors. Cables may not extend beyond the room in which they originate.  Cables may not be installed in closets, over cabinets that extend to the ceiling, under walls or partitions, or over walls or partitions that extend to the ceiling, except that single runs of cable may pass over partitions where embedded. This requirement does not prohibit low-temperature heat sources in closets to control relative humidity.

C.  Cables must be separated at least eight inches from lighting fixtures, outlets and junction boxes, and two inches from ventilating openings and other such openings in room surfaces, or sufficient area must be provided to assure that no heating cables will be covered by surface mounted lighting units.

D.  A separate manual disconnect must be provided for each space heated.

E.  Thermostatic control must be provided in each heated space, except that no individual thermostatic control may switch any combination of heaters totaling more than seven kilowatts.

F.  Thermostatic controls may not be installed on cable until the wattage has been inspected by a City Administrator and approval posted on the job.

1. 1.  In accordance with their individual listings.

2. 2.  No part of heater or heaters will be covered or blanketed by a door, draperies, curtains or other combustibles in such a manner as to raise the normal operating surface temperature of the unit.

3. 3.  A separate manual disconnect must be provided for each space heated.

4. 4.  Thermostatic control must be provided in each heated space, except that no individual control may switch any combination of heaters totaling more than seven kilowatts.

A.  A heater that is to be installed in an air duct or plenum must be approved for the purpose and must be installed in the manner approved for the equipment;

B.  Each such heater installation must be provided with approved controls, consisting of an airflow switch or pressure differential switch, that will disconnect the power supply to the heaters in the case of failure of a normal air flow across the heaters for any reason, such as blocked filters, motor failure, broken belts, shafts, or other driving equipment, etc., and must be provided with an approved temperature-limiting control. In addition, a supplementary independent control must also be provided in each duct heater to prevent overheating. This device must be manually resettable or replaceable;

C.  They may not be located outdoors, unless specifically approved;

D.  They may not be installed in downflow systems;

E.  Except for approved heater assemblies used in conjunction with a heat pump or central air conditioner, the heater may not be located closer than four feet to the flange of the heat pump or air conditioner unit;

F.  Two or more duct heaters may be installed in a group in duct work when specifically approved for this purpose and under such restrictions as may be necessary to ensure safe operation;

G.  Duct heaters must be approved for zero clearance from combustible materials, except that the terminal and/or control box of a duct heater must have a minimum access clearance of 24 inches to permit servicing and adjustment to the controls;

H.  An inspection panel with an area of not less than 140 square inches and a minimum dimension of five inches must be provided in the duct immediately adjacent to, and on the upstream side of, each electric duct heater. The panel must provide access for cleaning dust and debris from the heater and means for checking concealed heat limiters. The panel must be marked, “Disconnect heater before removing this panel.”

1. 1.  Exception: An access panel will not be required for electric duct heaters of the slide out type if they are supplied by flexible conduit and
   1. a.  Are readily removable.
   2. b.  Weigh less than 50 pounds.
   3. c.  Have a maximum dimension of three feet for that portion that extends into the duct,
2. 2.  A separate access panel will not be required where the electric duct heater is located within one foot of a removable room grill and the heater is removable through the grill opening;