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I will be replacing my dishwasher and I am curious what is the current code for the wiring of the dishwasher.

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Does the dishwasher have a cord and plug, or just a place to land a wire and connect it? –  Tim Post Mar 14 '13 at 5:21
I do not have the dishwasher currently to look at it, but I believe it has a place to land the wires. –  Brian Miller Mar 14 '13 at 5:32
I've answered, but it would be rather helpful if you could include some more information such as your location, and the results of any investigating you've done to try and locate a feed for it. –  Tim Post Mar 14 '13 at 6:01
I will Tim, I know the current dishwasher has a a place to terminate wires. I will add some photos tomorrow of the current set dishwasher and what is done when I get the new one. –  Brian Miller Mar 14 '13 at 7:38
It's an appliance, so you pretty much just connect it per the instructions (which should be to code). –  DA01 Mar 14 '13 at 18:23

2 Answers 2

up vote 4 down vote accepted

Assuming you're in the US (though I can't imagine it being much different elsewhere, but do check!) ...

Be sure to check the label, but most dishwashers run perfectly happy on a 15A circuit. If a dedicated circuit to the dishwasher isn't possible, you can come out of a general receptacle circuit that isn't otherwise utilized in the kitchen, depending on the rating of the dishwasher. What you want to avoid is a mixer and toaster and dishwasher using the same circuit at once. You may have to do some investigating. Go for the dedicated circuit if that's possible.

If the dishwasher has a cord and cap, you should have an appliance receptacle installed where it can be reached. An appliance receptacle is an outlet with only one place to plug something in. Since your dishwasher can not be on a GFCI circuit, this ensures that someone won't try to plug something else into the non-GFCI protected outlet while near ground potential (within six feet of anything wet, e.g the sink). Even if the plug is somewhat hidden or inaccessible, you want to be sure nothing else uses it. Be sure the receptacle is rated properly, they come in 15 and 20 amp varieties.

If the dishwasher has a place to just terminate a cable, purchase the appropriate connector for the type of cable you're using (likely ROMEX (non-metallic + bonded)) to go into the 1/2" opening, secure the connector properly and make the connections using wire nuts.

Be kind to your future self, or anyone else that has to pull the dishwasher out in the future to service it by leaving enough cable to be able to pull it out and off to the side. Make sure the cable is secured properly wherever it is fed, and protected anywhere that it may be exposed on its path to the dishwasher.

If uncertain or uneasy - you probably want to call an electrician.

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+1 for the 'be kind' suggestion! Nothing more infuriating than to realize they only left 1' of slack in the wiring when you go to pull it out. –  DA01 Mar 14 '13 at 18:25

Current code suggests a dedicated line run to the breaker box for use with the dishwasher. 2008 NEC indicates that the kitchen should have two 20 amp counter top circuits to run small appliances.[So you can run a microwave and a toaster at the same time.] The NEC also says that those circuits should not be used for anything else.

-In a retrofit situation, you could tap into the counter top circuit if there is no other option. Unfortunately, with this arrangement, the motor and heating element will consume most of your available amps leaving you in a situation where you cannot use other things while the dishwasher is running.

On use of grounding and GFCI's... No matter what you do, ground the dishwasher to a reliable ground. If you are using new wire, this will be easy. Just hook up the green or bare wire to the frame of the dishwasher and bond the other end to the breaker box ground. If it is an older home with a two wire system, You can bond the washer to copper or iron water pipe (NOT A GAS LINE!!!) For safety, be sure that the pipes are bonded to the box ground or at least earth ground.

There is no prohibition on the use of GFCI in this circuit. The electronics in new GFCI devices greatly reduces nuisance tripping. You can use a GFCI breaker, an outlet, or even a GFCI dead front. (This looks like a GFCI outlet with no holes to plug anything in- and could be mounted at the counter top for accessibility)

My installation: (Dishwasher recommends 15 - 20 amp) I ran #12 MC Flex up and over through the attic to the washer and popped out of the wall to a box attached to the inside of the cabinet next to the washer. I installed a 20A GFCI paired with the 20A breaker in the panel. I attached a #10 stranded appliance cord to the washer with a 20A plug. I did this so I could have GFCI protection and also if the washer had a significant malfunction requiring immediate reaction, the cord could be pulled out without having to find the right breaker. I have used this setup for over two years and have not had any trouble from it.

MC Flex (metal clad) is a bit of overkill for residential (unless your local building code requires it), you can just use Romex if you wish. If you are using #14 wire, do not exceed 15A. If you use #12 wire, you can safely use 20A breaker (unless your dishwasher specifies 15A only.)

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Bonding to a cold water pipe in just any location IS NOT code acceptable any more. This was disallowed many years ago. The only thing that is allowed is if the pipe is being used as a grounding electrode and the connection is made within 5' of where the pipe enters the building since this is the only section of that pipe that is considered the grounding electrode. You can also ground/bond it to any point in the grounding electrode system or grounding electrode conductor. In such cases many times it is just as easy to run a new circuit. –  Speedy Petey Jun 8 '14 at 14:46
If you are interested see NEC 250.130(C) –  Speedy Petey Jun 8 '14 at 14:48
@SpeedyPetey You are right, I am soooo wrong. It is best to just not ground your equipment at all if it is not up to NEC specs... No, It is true, If you can run a new circuit, that is the best thing. But if you are in a situation where you need to add the safety of a ground and you cannot run a new line for whatever reason, is it better to utilize an older code model and be safer than doing nothing at all? –  Posted by another Tim Jun 8 '14 at 21:06
NO! It is NOT better to utilize an old code. THAT is why the code changed. Either do it right or don't do it at all. –  Speedy Petey Jun 8 '14 at 22:44
Codes change because the change is usually better. Example: code says- outlet every 6ft. but if you are renovating an older home, sometimes it is just not practical. it is better to settle for 2 or 3 correctly wired outlets in a room than just stay with the original 1. If you are adding an appliance and you cannot run a new line, I would think clamping to other grounded metal is better than electrocution induced cardiac arrest. We should all strive for "CODE" but sometimes, Old houses don't cooperate. –  Posted by another Tim Jun 8 '14 at 23:09

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