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Electric baseboard (C) Daniel Friedman Electric Heating Baseboard Requirements
How Many Feet of Baseboard? Compare Baseboard vs FanHeaters

Electric baseboard heat linear feet neeed: how to detrmine how many feet of electric baseboard are needed to heat a building, space, or area.

Electric baseboard heat installation, calculations, wiring: in this article series we explain how to install and wire electric heating baseboards.

Here we also compare the features of a portable or permanently-installed electric fan heater with electric baseboard heat.

This article series answers most questions about all types of heating systems and gives important inspection, safety, and repair advice.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

How Many Linear Feet of Electric Baseboard Heat do we Need in a Building?

Electric heat capacity rules of thumb (C) Carson Dunlop Associates

Here are some electric heat rules of thumb that will help you see if the electric baseboard already installed in your building will be sufficient. These guesstimates presume your building is located in a climate where there are real winters, not in southern states.

A larger room or a poorly-insulated building will need more watts of electric heat (and pay higher electrical bills).

[Click to enlarge any image]

As Carson Dunlop Associates' sketch shows, you can figure that your electric baseboard is providing about 250 watts of electric heat per foot of baseboard length.

If you don't know what kind of heat your building uses, we explain how to figure out the answer
at HEATING SYSTEM TYPES.

Below is a table of typical electrical heater wattage requirements or heater size based on room area in square feet.

Electrical Baseboard Watts, Length, Circuit Size Chart1

Room Area Electric Heat Needed Baseboard Length Baseboard Watts Circuit Size
8 x 8 = 64 sq.ft. 320 - 512 Watts 2 ft. 500 W 15 A / 120V or 240V
8 x 10 = 80 sq.ft. 400 - 640 Watts 2.5 ft. 640 W 15 A / 120 V or 240V
10 x 10 = 100 sq.ft. 500 - 800 Watts 3 ft. 800 W 15 A / 120 V or 240V
10 x 12 = 120 sq.ft. 600 - 960 Watts 4 ft. 1000 W 15 A / 120 V or 240V
15 x 20 = 300 sq.ft. 1,500 - 2,400 Watts 6 - 10 ft. 2,500 W 15 A 240V
20 x 24 = 480 sq.ft. 2,400 - 3,840 Watts 10 - 16 ft. 2,500 - 4,000 W 20 A 240V - 30 A 240V
20 x 30 = 600 sq.ft. 3,000 - 4,800 Watts 12 - 20 ft. 3,000 - 5000 W 30 A 240V
20 x 30 = 600 sq.ft. 5,000 - 7,600 Watts 20 - 30 ft. 5,000 - 7,600 W 30 A 240V - 40 A 240V

1. Watch out: These room sizes and heater sizes are approximate; important additional factors such as the temperature difference between indoors and outdoors, the building air leakage rate, and building insulation will of course affect the amount of heat needed to keep occupants comfortable in cold weather.

2. Watch out: when selecting the electrical circuit size you must consider the total wattage of all of the electric heaters that will be used on the circuit. Do not exceed the total wattage permitted for the wire and circuit breaker size.

If you need more heat in an area than a single circuit can provide in watts, run additional circuits to the area to permit dividing the electric heater load among circuits.

Separately at ELECTRIC BASEBOARD HEAT INSTALL we give details of electric heat circuit requirements such as wire and circuit breaker size based on electric heater size in total watts.

Comparison of Features of a Portable Or Installed Electric Fan Heater versus Electric Baseboard Heaters

Electric Baseboard Heat vs. Electric Fan Heaters
Feature Electric Baseboard Heat Electric Fan Heat
Heat Use Type

Suitable for primary heat source

Permanently installed

Use steel element heater if primary heat source

Also may be permanently installed

Open coil elements suitable for supplemental or occasional use
Room Heat Speed 30-40 minutes Less than 10 minutes
Room Temperature Variation Heat is concentrated at baseboards Fan circulates room air, heats more evenly
Heater Efficiency    
Heater Operating Cost1 Slower room heating increases operating cost. Circulating air may speeds room heating and reduces operating cost.
Heater Noise Nearly silent; some thermal expansion noises

Varies by fan type2 & speed, very quiet to audible blower fan noise.
Heater Space Needed Consumes wall space, don't block by anything Smaller space occupied by heater; don't block by anything
Heater Life Expectancy 20+ years3 8-12 Years3

Notes to the Table Above Comparing Baseboard Heaters with Electric Fan Heaters

1. Electric baseboard heat is the least expensive to install but is the most-expensive (per BTUh of heat output) for most areas in North America.

Electric heat is 100% efficient in that virtually all of the energy consumed is being delivered as heat.

Electrical circuit voltage (120 vs. 240 VAC) choice will not change the operating cost of the electric heater, but electrical circuit installation costs may be less with a 240 VAC circuit where multiple heaters are required, because more heaters can be installed on the circuit.

For example a 20A 120V electrical circuit can support a baseboard heater with maximum heat output of 1920 Watts while a 20A 240V circuit can support a total electric baseboard heat output of twice that amount, or 3840 Watts.

Propeller fan type fan heater installed in a bathroom (C) Daniel Friedman at InspectApedia.com

2. For the same CFM output, propeller type heater fans are noisier than squirrel cage type heater fans. Two small fan heaters in a rooom will produce less total noise than a large heater specified to heat the same area.

Above: our photo shows a propeller-type fan heater being installed in the exterior wall of a bathroom in a New York study.

3. Source: Suarez, Paul, "Which is right for your room, a baseboard or wall heater?" Cadet Heat, 2500 West 4th Plain Blvd. Vancouver, WA 98660 USA, Website: cadetheat.com, Email: customerservice@cadetheat.com Tel: 855-223-3878 / International: 1-360-693-2505, retrieved 2018/09/09, original source: http://cadetheat.com/blog/baseboard-or-wall-heater/

Adapted from King Electric, ELECTRIC HEAT WIRING CIRCUIT SIZING CHART [PDF] King Electrical Manufacturing Co., cited in detail below, retrieved 2018/09/10, original source: https://www.king-electric.com/pdfs/helpful-hints-sizing-chart.pdf

At ELECTRIC BASEBOARD HEAT INSTALL we give electric heat circuit requirements based on electric heater size in total watts.

Example of Cord-and-Plug Electric Fan Heater Sizes & Circuits

See details at ELECTRIC BASEBOARD HEAT INSTALL

Portions of this article are adapted from KING ELECTRIC CB-SERIES ELECTRIC BASEBOARD HEAT INSTALLATION [PDF] King Electrical Mfg. Co., 9131 10th Avenue South, Seattle, WA 98108 USA Tel: 206.762.0400 Website www.king-electric.com

U.S. Electrical Code Guidance on Electrical Current Load vs Wire Size for Cord-and-Plug-Connected Electric Heaters

NEC 210.21 (B) Receptacles.

(1) Single Receptacle on an Individual Branch Circuit.

A single receptacle installed on an individual branch circuit shall have an ampere rating of not less than that of the branch circuit.

Exception No. 1: A receptacle installed in accordance with 430.81(B)/

Exception No. 2: A receptacle installed exclusively for the use of a cord-and-plug-connected arc welder shall be permitted to have an ampere rating of not less than the minimum branch-circuit conductor ampacity determined by 630.11(A) for arc welders.

NEC 210.21 (B) Receptacles. (continued)

(2) Total Cord-and-Plug-Connected Load.

Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord-and-plug-connected load in excess of the maximum specified in Table 210.21(B)(2).

That table specifies the following:

Circuit Rating (Amperes) 15 or 20, Receptacle Rating (Amperes) 15, Maximum Load (Amperes) 12

Circuit Rating (Amperes) 20, Receptacle Rating (Amperes) 20, Maximum Load (Amperes) 16

Circuit Rating (Amperes) 30, Receptacle Rating (Amperes) 30, Maximum Load (Amperes) 24

See ELECTRICAL CODES to download copies of various electrical codes and standards.

Also see ELECTRICAL RECEPTACLE HEIGHT & CLEARANCES for a discussion of avoiding fire hazards of electrical receptacles installed above electric baseboard heaters.

Electric Heater Locations in Buildings

This discussion has been promoted! It has its own page now found at ELECTRIC HEATER LOCATIONS.

(Nov 14, 2012) Louis Bernardini said: I need a wiring diagram for a Singer model 7165B electric baseboard unit.


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Articles on Electric Heat

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