Author Topic: Installing a dishwasher- Does it really need a dedicated circuit?  (Read 84789 times)

Miss Growing Green

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We're installing a dishwasher where there wasn't one before.  In the manual it "recommends" the DW be on a dedicated 15 OR 20 A circuit.  This is a new Energy Star dishwasher, so the power draw is relatively low (9.6 amps, or 1152 watts).  We currently have two 20A circuits in our kitchen, which each supply three outlets.  Would it be insane to just move one of the outlets to the new DW spot and have a circuit with the DW and two outlets on it?

Obviously I want to do what is safe, but the recommendation of "dishwasher on it's own circuit" can't be universal when all dishwasher pull different electric loads, and they could be on either a 15 or 20A circuit, right?  According to my numbers, a 20A circuit should be fine with a maximum draw of 1920 watts. Sooo, what do you think?  Running a new circuit would turn a pretty easy job into a nightmare-ish remodel, which is why we're trying to avoid it.

GuitarStv

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #1 on: March 12, 2014, 11:20:52 AM »
A 15 amp circuit at standard North American voltage (115) can handle 1725 watts, a 20 amp one can handle 2300 watts.  Around here, building code says that you can't load more than 80% per breaker, so you can put about 1840 watts on the circuit.  That would leave about 600 watts free on your 20 amp breaker, for use via the three outlets when you're running the dishwasher.  Sounds reasonable to me.

Nate R

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #2 on: March 12, 2014, 11:28:34 AM »
Code legal? No. Safe? I don't see why not. If it's allowed on a 20A breaker, and you're not overloading that breaker, no problem.  Just don't plan to run the DW and the coffeemaker or microwave on the circuit at the same time.

I did a similar thing recently. Removed a junky 24" cabinet, put in a dishwasher. Tapped into an existing circuit (One that was only one kitchen receptacle otherwise.) I'll do it correctly when I remodel the kitchen in a few years. But this works for now, and I just am aware that I can't run other heavy loads on the circuit when the dishwasher is drying. (This is usually when the highest power draw is)

-Nate

Milspecstache

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #3 on: March 12, 2014, 05:46:19 PM »
+1 to what Nate R says.

It really just requires you to strategically position devices with the understanding that a dishwasher cycle pulls a pretty good load during the drying cycle where it turns heaters on.  That is not the time to have, say, a breadmaker also in its heating cycle as well.

Rural

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #4 on: March 12, 2014, 07:26:09 PM »
No need to heat dry dishes at all. Once you install the dishwasher, set it to air dry and save load on the circuit and electricity costs at the same time. Win-win.

Sparky

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #5 on: March 12, 2014, 08:38:33 PM »
"If your local code requires it on a separate breaker, then put it on a separate breaker". Okay I said it as I have to as an Electricianů.

However in reality, it is perfectly safe to run it on another circuit, as long as the circuit breaker (fuse) is rated for 115V 15A or 20A. I would highly not recommend installing on the same circuit as your refrigerator as they are typically a dedicated circuit for that load only, avoid the circuits on your countertops if possible and obviously don't use the circuits from your electric stove or dryer   Everything else within reason is fair game.

Running the cable is about 90% of the battle for your project, you might have to get pretty creative and might end up repairing a bit of drywall. Wiring is as simple as reading the instructions and putting the colours together :)
« Last Edit: March 12, 2014, 08:44:58 PM by Sparky »

Greg

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #6 on: March 12, 2014, 11:02:38 PM »
Another non-code-compliant solution is to install an appliance cord and run it through the cabinet into the sink base and plug it into the outlet for the disposal if you have one.  In my area dishwashers are supposed to be hard wired, not sure why, but this could make it easier to do.  Also, if you do have a disposal outlet, it's likely a dedicated circuit.  Be sure to get a cord rated for at least the amperage of the appliance, and be sure it's a grounded (3 wire) cord.

Miss Growing Green

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #7 on: March 14, 2014, 09:15:29 AM »
Thanks for all the suggestions, everyone!  Good to know I have some options and it can be done-  I'll make sure it's not sharing a circuit with a major appliance like the fridge or microwave.  Again, thanks for all the thoughtful advice!

paddedhat

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #8 on: March 28, 2014, 08:11:52 PM »
Another non-code-compliant solution is to install an appliance cord and run it through the cabinet into the sink base and plug it into the outlet for the disposal if you have one.  In my area dishwashers are supposed to be hard wired, not sure why, but this could make it easier to do.  Also, if you do have a disposal outlet, it's likely a dedicated circuit.  Be sure to get a cord rated for at least the amperage of the appliance, and be sure it's a grounded (3 wire) cord.
 

Actually current "service disconnect" requirements in the code provide a few options, including a breaker lock at the panel, a switch dedicated to the dishwasher (stupid choice) or using an appliance cord to wire the unit and plugging it in to a receptacle in an adjacent cabinet. I typically do the last option.  IF you have a cord connected garbage disposal below the sink, I would really suggest that you wire the DW with a "15 amp, grounded, power tool replacement cord" found in the extension cord department in Lowes or HD. It's a slick way of doing the job, and it makes it pretty sweet to disconnect the power to service the unit.  As to the original question, combining the DW and two additional outlets in the kitchen will work just fine. Finally,  get the braided stainless steel supply hose for the dishwasher and install a 1/4 turn ball valve to shut it off. Good luck.

Vilx-

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #9 on: March 29, 2014, 02:53:34 AM »
Also, to add on the safety side - the worst thing you're risking is that you'll trip the circuit breaker and will be left without power on that circuit. No electrical fires or anything.

el Katz

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #10 on: April 08, 2014, 06:31:55 PM »
And let us not forget a GFCI.

paddedhat

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #11 on: April 08, 2014, 09:38:38 PM »
And let us not forget a GFCI.
Nope, not standard procedure, a code requirement, or even a good idea. Since there is no need for it in this application, and typically (assuming that you are referring to an outlet and not a breaker) the outlet would be located under the sink base, it would also create troubleshooting issues in the future. GFCIs are somewhat failure prone, and I doubt most folks would even think to look for one there before making a call to the appliance repair guy when the dishwasher quits.

As a safety measure, when I do install dishwashers with a plug in cord, I always use a single outlet under the sink, as opposed to a standard duplex, which would leave a non-GFCI spare place to plug in to. I have no idea why anybody would want to plug in there, but I like to eliminate the possibility.

Wesmon

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #12 on: April 18, 2014, 07:20:44 AM »
Quote
But this works for now, and I just am aware that I can't run other heavy loads on the circuit when the dishwasher is drying. (This is usually when the highest power draw is)

-Nate

FACE PUNCH! There is no reason to use the dry cycle on a dishwasher.

Nate R

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #13 on: April 21, 2014, 08:53:15 AM »
Quote
But this works for now, and I just am aware that I can't run other heavy loads on the circuit when the dishwasher is drying. (This is usually when the highest power draw is)

-Nate

FACE PUNCH! There is no reason to use the dry cycle on a dishwasher.

Good call! I'm relatively new to the luxury of having a dishwasher......haven't tried running it w/o the heated dry yet! Thanks for the gentle face punch, I'll try that on the next load! :-)

ETA: I DO only run the dishwasher during my off-peak electric hours. (I'm signed up for a time of use plan.) So it IS cheaper than most in the area to run. (9 cents/KWH off peak instead of 14 cents for standard plans.)
« Last Edit: April 21, 2014, 08:55:34 AM by Nate R »

Spork

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #14 on: April 21, 2014, 09:26:23 AM »
And let us not forget a GFCI.


As a safety measure, when I do install dishwashers with a plug in cord, I always use a single outlet under the sink, as opposed to a standard duplex, which would leave a non-GFCI spare place to plug in to. I have no idea why anybody would want to plug in there, but I like to eliminate the possibility.

What I see around these parts (and have no idea if "it's code" or not... just what I commonly see) ...   I usually see a normal duplex receptacle where the tab has been removed and it is split between 2 circuits: one to dishwasher and one to disposer.

searc99

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #15 on: December 19, 2018, 11:12:51 AM »
No need to heat dry dishes at all. Once you install the dishwasher, set it to air dry and save load on the circuit and electricity costs at the same time. Win-win.

I agree with that, 100%.

But I would point out that that same heating coil is used to heat the wash water if your hot water is below the temperature required for proper operation of the dishwasher (I'm not sure, but suspect that is 140 degrees, many people set the temperature at their hot water heater below that to save electricity and / or minimize the chance of burns (especially to infants).

Thus, turning off hot air drying will save electricity, but may not reduce the load on the breaker.

And boy, is the site a pain in the ass, first to register, and now to post!!!!!

m8547

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Re: Installing a dishwasher- Does it really need a dedicated circuit?
« Reply #16 on: January 15, 2019, 09:33:48 PM »
And let us not forget a GFCI.
Nope, not standard procedure, a code requirement, or even a good idea. Since there is no need for it in this application, and typically (assuming that you are referring to an outlet and not a breaker) the outlet would be located under the sink base, it would also create troubleshooting issues in the future. GFCIs are somewhat failure prone, and I doubt most folks would even think to look for one there before making a call to the appliance repair guy when the dishwasher quits.

As a safety measure, when I do install dishwashers with a plug in cord, I always use a single outlet under the sink, as opposed to a standard duplex, which would leave a non-GFCI spare place to plug in to. I have no idea why anybody would want to plug in there, but I like to eliminate the possibility.

GFCI is required for dishwashers as of NEC 2014. The rationale is there's a possible failure mode in the motors that GFCI protects against. The downside is the GFCI has to be accessible, so the reset can't be behind the dishwasher.

I think it makes sense for the dishwasher and garbage disposal (which gets used infrequently for very short times) to share a circuit, but if you read enough of the code, it's not clear if that's technically allowed (something about motor loads).