120V
Length
Heated area spacing (ft²)
Watts
Amps
Ohms
Fast Set
Strapping
Model
ft
m
2”
3”
4”
FC12120
40
12.2
5
10
15
120
1.0
120.0
20 ft.
FC12180
60
18.3
10
15
20
180
1.5
80.0
20 ft.
FC12240
80
24.4
15
20
25
240
2.0
60.0
20 ft.
FC12300
100
30.5
18
25
35
300
2.5
48.0
20 ft.
FC12360
120
36.6
20
30
40
360
3.0
40.0
40 ft.
FC12480
160
48.8
25
40
55
480
4.0
30.0
40 ft.
FC12600
200
61.0
35
50
65
600
5.0
24.0
40 ft.
FC12720
240
73.2
40
60
80
720
6.0
20.0
60 ft.
FC12840
280
85.3
45
70
95
840
7.0
17.1
60 ft.
FC12960
320
97.5
55
80
105
960
8.0
15.0
60 ft.
FC121080
360
109.7
60
90
120
1080
9.0
13.3
80 ft.
FC121200
400
121.9
65
100
135
1200
10.0
12.0
80 ft.
King Electrical Floor Heating Cable Installation Manual
8
STEP 2: Layout planning and product selection
2.5
Border allowance: Heating cable should be installed between 1” and 6” from the perimeter walls, but not more
than 1.5” from a kick space vanity, shower, bathtub, counter or doorway. It is not necessary to heat the floor all
the way to the wall as it is not typical that people will stand that close to the walls. In addition, the heat will
radiate out an additional 2” from where the cable is embedded.
2.6
In most cases simply select the cable kit that is 5% but no more than 10% less that the total square footage of
the area to be heated as calculated in the previous step. For example: if the square footage after deduction the
fixed obstacles equals 74 ft , then the closest cable kit is 70 ft which is 5.4% less allowing for an unheated border.
The next size down is 60 ft which is too small and would not be enough cable to properly heat the room.
2.7
Selecting the cable spacing:
A. 3” is the standard spacing and recommended for most flooring heating applications.
B. 2” spacing is used for high heat loss applications such as a non-insulated concrete basement floor or bathroom
with a large exterior wall.
C. 4” spacing is used in low heat loss applications such as in warmer climates where there is a modest temperature
rise of less than 15 F is all that is needed.
2.8
Select either 120 or 240 volt cable depending on the power supply available. DO NOT mix voltages on the same
system when more than one cable is used to cover a room.
(continued)
2
2
