What gauge wire should be used?
When selecting the right amperage supply and cable gauge for your Warmup system, you must first assess the total amperage drawn by the installed system. Amperage can be found on the product labels and in the Technical Spec Sheets. All supply lines powering the system should be stranded 3-wire copper wire including a ground (hot/hot/ground for 240V and hot/neutral/ground for 120V).
Warmup Thermostats and Relays
Based on the chart below, a Warmup thermostat can switch up to 1,800 watts of power (15A/120V) or 3,600 Watts at 240V.
A Relay25 can switch up to 6,000 watts of heaters at 240V. However, Warmup recommends not maxing out a relay to its ultimate switching capacity in order to ensure safe and long-lasting operation. A recommended maximum of 5,400 watts/240 Volts is advised.
Powering a System
When powering a system, total the amperage of the system and feed it with a breaker that carries at least 20% extra power.
10 Amps system + 20% (2 Amps) = 12 Amps supply minimum.
Based on NEC guidelines, such a supply requires a 14 Gauge supply line.
While it is always advised to use dedicated supply lines for Warmup systems, when using an existing electrical circuit, ensure that the same amperage capacity is available on the circuit. That is, the total of the Warmup heating system +20%.
when adding a 30 sqft cable heater (420 Watts / 120 Volts) you will need enough supply to cover 3.5 Amps of draw (the heater) + 0.7 Amps (20% safety) for a total of 4.2 Amps. Your existing circuit will need to have 4.2 Amps available to support the Warmup system.
By the information provided herein, Warmup does not substitute itself to the responsibility of the licensed electrician or electrical contractor completing the work. Warmup supplies this information merely as a guideline based on the NEC and all final wiring decisions remain the responsibility of the electrician.
DCM-PRO: 17 Gauge
Larger Mats/Cables: 14 Gauge
Snowmelt: 10 Gauge