Electric Tankless Water Heater Wiring in Los Angeles

Swapping a bulky tank for an on-demand system saves space and gives you endless hot water — but an electric tankless water heater is one of the most electrically demanding appliances you can add to a home. In most Los Angeles houses, the wiring and panel need a hard look before a single pipe is touched.

How Much Power an Electric Tankless Unit Really Needs

A whole-home electric tankless water heater typically draws 18 to 36 kilowatts. In practical terms that means two to four double-pole (240-volt) breakers and a total demand of roughly 80 to 150 amps just for the water heater — often more than an entire older home was originally built to handle.

That is very different from a gas tankless unit, which only needs a small 120-volt circuit for its igniter and controls. If you are switching from gas to electric, budget for a real wiring project, not a quick swap.

Electrical Requirements: Breakers, Wire, and Panel Space

Every model is different, so the tankless water heater electrical requirements always come from the manufacturer's spec sheet. In general, a proper install includes:

• Breaker size: multiple 40- to 60-amp double-pole breakers sized to the unit's rated wattage.
• Wire gauge: heavy copper — commonly 6 AWG or 8 AWG per circuit — on dedicated home runs to the heater.
• Dedicated circuits: each heating-element bank needs its own dedicated circuit and cannot share with other loads.
• Panel space: two to four open breaker slots, which many full LA panels simply don't have.
• Load calculation: a licensed electrician runs a full load calc to confirm your service can carry the added demand.

Do You Need a Panel Upgrade in Los Angeles?

Plenty of homes in Pasadena, Highland Park, Eagle Rock, and across the San Fernando Valley still run on 100-amp service. Add an 80- to 150-amp water heater to that and the numbers rarely work. In those cases a 200-amp panel upgrade is the safe, code-compliant path forward — the same upgrade many homeowners already plan when adding an EV charger or other big loads.

Not sure what your panel can support? Our guide to electrical panel upgrades in Los Angeles walks through when an upgrade is worth it and what it involves.

Permits, Code, and Safety

An electric tankless install is not a permit-optional job. Los Angeles and surrounding cities require an electrical permit and inspection, and the work must meet the California Electrical Code — correct breaker sizing, proper wire gauge, dedicated circuits, and solid grounding and bonding. Skipping the permit can create insurance and resale headaches later, and undersized wiring on a high-wattage circuit is a genuine fire risk.

If your existing wiring shows its age during the project, it is often smart to bundle any needed electrical repairs while the walls are open.

What the Electrical Work Typically Costs

Every home is different, so treat these as ballpark ranges — your electrician should verify pricing after seeing your panel and layout:

• Electrical work alone: often about $600 to $2,500+, depending on breaker count and how far the runs are from the panel.
• Panel upgrade (if required): commonly $2,500 to $5,000+ for a 200-amp service upgrade.
• Other factors: wall and attic access, permit fees, and utility coordination all move the final number.

Prices and any available rebates change over time and should always be confirmed for your specific project.

Frequently Asked Questions

Does an electric tankless water heater need a dedicated circuit?

Yes. Each heating-element bank requires its own dedicated 240-volt circuit sized to the manufacturer's specs. These circuits cannot be shared with outlets, lights, or other appliances.

What breaker size does an electric tankless water heater use?

Most whole-home units need two to four double-pole breakers, typically in the 40- to 60-amp range each. The exact electric tankless water heater breaker size depends on the unit's kilowatt rating, so always follow the spec sheet.

Can I run an electric tankless heater on a 100-amp panel?

Usually not for a whole-home unit. Once you add 80 to 150 amps of water-heater demand to a 100-amp service, there is rarely enough capacity left. A 200-amp panel upgrade is often required.

Is electric or gas tankless easier to wire?

Gas tankless units are far simpler electrically — they only need a small 120-volt control circuit. Electric models require heavy dedicated circuits and, frequently, a panel upgrade.

Do I need a permit in Los Angeles?

Yes. A permit and inspection are required for the electrical work. A licensed C-10 electrician will pull the permit and make sure the install passes code.

Get Your Electric Tankless Install Done Right

911 Construction & Electric Inc. is a licensed, bonded, and insured C-10 electrical contractor (CA Lic. #1027421) serving Los Angeles and nearby cities — Pasadena, Burbank, Glendale, Altadena, the San Fernando Valley, and beyond. We size the circuits, handle the panel upgrade if you need one, and pull the permit so your electric tankless water heater installation is safe and code-compliant. Contact us for a free estimate or call 747-255-8595 today.