Does an under sink water heater need a dedicated circuit?

Quick Answer

Most under sink water heaters do not require a dedicated circuit, but there are a few exceptions. Small under sink water heaters that draw less than 15 amps of power can typically run safely on a shared household circuit. Larger tankless or whole house under sink heaters that draw more power will need a dedicated circuit to avoid overloading. Always check the amp rating on your heater and follow the manufacturer’s wiring recommendations. If in doubt, consult an electrician.

Do Under Sink Water Heaters Need Their Own Circuit?

Whether an under sink water heater needs a dedicated circuit depends primarily on how much power it draws. Here are some general guidelines:

• Under sink water heaters under 1500 watts (12.5 amps at 120 volts) can often share a household circuit safely. This covers most compact electric tank and point-of-use heaters.
• Larger electric under sink water heaters from 1500-4000 watts should have a dedicated 15 amp circuit.
• Whole house electric under sink heaters over 4000 watts need a 20 amp or greater dedicated circuit.
• Gas under sink water heaters have lower electrical needs and can often use a shared circuit, but check manufacturer requirements.

Always check the amperage rating and manufacturer’s wiring instructions for your specific heater model. These provide the definitive guidance on whether a dedicated circuit is required.

When in doubt, consult an electrician. An undersized electrical circuit can lead to nuisance tripping, performance issues, and potential fire hazards. Spending a little extra on proper wiring during installation is worth avoiding these risks.

Typical Power Draw of Under Sink Water Heaters

Here are some approximate power draws for common under sink water heater types:

Under Sink Water Heater Type	Typical Power Draw
Compact electric tank heater (2-6 gallons)	1000-1500 watts
Small electric tankless heater	1500-2000 watts
Larger electric tankless heater	3000-4000 watts
Gas tankless heater	30-60 watts (for controls)
Whole house electric heater	4000-6000 watts

These are just general estimates – the actual power draw depends on factors like water flow rate, heating capacity, and features. Always check your specific appliance for accurate electrical requirements.

Special Considerations for Gas Under Sink Heaters

Gas powered under sink water heaters have very minimal electrical needs. They require electricity just to run electronic ignition systems and temperature controls. This is usually under 100 watts.

So gas under sink heaters can often safely share a small appliance electrical circuit. However, be sure to check the manual to see if your model has any special wiring requirements. Some gas heaters may specify a dedicated circuit.

One other consideration is that a shared circuit power outage could affect the electronics and temperature regulation on a gas heater. For maximum reliability, use a dedicated circuit. But it’s generally not an absolute requirement.

Can Multiple Under Sink Heaters Share a Circuit?

If you need to install multiple under sink water heaters, they may be able to share the same dedicated circuit provided the total load does not exceed the circuit amperage.

For example, two small 1500 watt heaters could potentially share a 20 amp dedicated circuit. But three 2000 watt heaters on the same circuit could overload it. Always calculate the total projected amp draw and compare it to the circuit rating.

Also be aware that multiple heaters running simultaneously will draw more power. So while they may share a circuit, the circuit needs to be sized to handle peak demand.

Consult an electrician if wiring multiple under sink heaters to determine the required circuit size. It’s better to allow extra capacity than overload a circuit.

Key Electrical Specs to Check

When determining if your under sink water heater needs a dedicated circuit, be sure to check these key specifications:

• Wattage rating – This shows the maximum power draw.
• Current (amps) – The current rating based on wattage and voltage.
• Recommended circuit size – Advice if a 15 amp circuit is sufficient or 20 amps is needed.
• Special wiring requirements – Any specifications for dedicated circuits or wire gauge.

Compare the electrical requirements to your available household circuits to see if adding a new dedicated line is advised. Undersized wiring can lead to problems.

Installing a Dedicated Circuit

If your under sink water heater does require a dedicated circuit, an electrician will need to install new wiring from your electrical panel to the heater location.

Here is a quick overview of this process:

• A new circuit breaker is installed in the main service panel, sized for the appliance load (usually 15 or 20 amps).
• Wiring is run from the new breaker to under sink area. 12 or 10 gauge is normally used for 15/20 amp circuits.
• Power is brought up to a new electrical box mounted under the sink or on a nearby wall.
• The heater is wired to this new box and grounded properly.

All wiring must follow local electrical codes for proper circuit sizing, wire gauge, connections, and grounding. Permit and inspection may be required in some areas.

Hiring a qualified electrician ensures the circuit is installed safely and correctly for the under sink heater’s power needs.

Connecting to an Existing Dedicated Circuit

If you already have a dedicated circuit available near the sink, you may be able to use this existing wiring for the under sink heater provided:

• The circuit has sufficient amp capacity – Match it to heater requirements.
• The wire gauge is appropriate – Small gauges can’t handle high amp loads.
• It serves your intended purpose – Don’t overload a critical circuit.
• You verify it’s properly wired and grounded.

Never assume an existing mystery circuit is suitable – have an electrician assess it first. Attempting to use undersized or improperly wired circuits can cause serious hazards.

Minor modifications like a new outlet may be needed to utilize the existing circuit. But this is still cheaper than running all new wiring.

Using a GFCI Outlet

Under sink water heaters should always be connected to a GFCI protected circuit for safety near plumbing fixtures. This provides protection if the appliance develops an electrical fault.

Standard practice is to use a GFCI outlet or breaker:

• GFCI outlet – Install within 3 feet of the heater. Provides protection just for that circuit.
• GFCI breaker – Install in the main panel. Protects the entire circuit.

The wiring must still be rated for the heater’s power needs. The GFCI just adds leakage protection.

Never plug a high wattage under sink heater into a small household outlet without verifying it is on a suitable circuit. Use a GFCI outlet but ensure adequate circuit capacity first.

Conclusion

Always consult the product specifications and manufacturer’s wiring instructions for your particular under sink water heater model. While general guidelines can provide a starting point, your specific heater’s power demands determine if a dedicated circuit is actually required.

For under sink heaters that need their own circuit, hire a qualified electrician to install new wiring with adequate capacity. Never overload existing household circuits with large electrical appliances. Taking the time to properly wire your heater ensures safe and reliable performance.