Author Topic: Breaker Size  (Read 597 times)

Offline walker

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Breaker Size
« on: May 26, 2017, 04:15:12 PM »
Anyone know what size breaker this electric water heater would use?  It's a 120v

https://www.lowes.ca/products/view.aspx?sku=10932457

Couldn't find anything in the manual, unless I missed it.

Offline walker

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Re: Breaker Size
« Reply #1 on: May 26, 2017, 05:28:34 PM »
I'm guessing 30amp as it says to use 10AWG wire?

Offline Admin

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Re: Breaker Size
« Reply #2 on: May 26, 2017, 08:49:22 PM »
Maybe the rating plate will list the maximum overcurrent protection.

If you're installing it in a mobile home you can use a 15A breaker.

Quote
70-120 Branch circuits — Mobile homes
(3) Notwithstanding Rule 8-104, a circuit supplying an electric water heater having an input not more than 1500 W at 115 V or 3000 W at 230 V shall be permitted to have overcurrent protection rated or set at 15 A.

1500W / 120V = 12.5A

Quote
8-104 Maximum circuit loading
6) Where a fused switch or circuit breaker is marked for continuous operation at 80% of the ampere rating of its overcurrent devices, the continuous load as determined from the calculated load shall not exceed
(a) 80% of the rating of the circuit where the ampacity of the conductors is based on Column 2, 3, or 4 of Table 2 or 4; or

12.5A x 1.8 = 22.5A

Technically you can use a 25A breaker and #10 wire, but a 30A will also work.

Quote
14-104 Rating of overcurrent devices
(2) Except as provided for by Subrule (1)(c), the rating of overcurrent protection shall not exceed
(a) 15 A for No. 14 AWG copper conductors;
(b) 20 A for No. 12 AWG copper conductors;
(c) 30 A for No. 10 AWG copper conductors;
(d) 15 A for No. 12 AWG aluminum conductors; and
(e) 25 A for No. 10 AWG aluminum conductors.

Offline Porcupinepuffer

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Re: Breaker Size
« Reply #3 on: May 28, 2017, 08:41:03 AM »
If the manual wants you to use 10, I'd stick with that. I would also use a 15a breaker since the codes the admin posted says you can do so. If the breaker ends up tripping, there's something wrong with the tank.

I remember doing a lot of electric water heaters in the past. Never a 120v one. We would use #12 with the 3000w/240v tanks and a 20 a breaker... Every so often a customer would get the better quality tank that had the 4500w/240v heaters and we would go to #10 and a 30a breaker.

If the tank doesn't come with the plastic drain tube for the pressure relief, make sure you install one with the correct maximum distance from the floor.