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lmorsino 02-11-2013 11:38 PM

Wiring up a dishwasher and disposal
 
I'm renovating my kitchen, and on the permit, the building official notes that the dishwasher and food disposal unit

"must be on two separate circuits of 20A each"

Does the code allow me to hook up any other recepticles on the same circuit as the appliance as long as the two appliances are not together on the same circuit? Or does "separate" really mean "dedicated"? 20A dedicated for each appliance sounds like overkill and I'd like to put more recepticles on those circuits as I'm quickly using up space in the breaker box.

I know I could go down to city hall and ask them personally but that's a hassle and just thought I'd ask you guys if this is a code requirement. What is commonly done in this situation?

Thanks!

k_buz 02-11-2013 11:52 PM

From what the inspector is saying, you need to install a separate 20A circuit for each appliance.

This is not a NEC requirement. This would be a local amendment to the NEC.

rrolleston 02-12-2013 12:41 AM

Sometimes you can run them on a MWBC- "Multi Wire Branch Circuit". You run 12-3 on a double pole breaker and split the neutral at the junction. I kinda like this since you have to turn both off to work on one of the other. They are piped together and I like doing it that way.

Of course you should check with the local inspector to see what he thinks.

You could also ask if that is a local code amendment or NEC requirement.

frenchelectrican 02-12-2013 02:28 AM

Quote:

Originally Posted by lmorsino (Post 1115451)
I'm renovating my kitchen, and on the permit, the building official notes that the dishwasher and food disposal unit

"must be on two separate circuits of 20A each"

Does the code allow me to hook up any other recepticles on the same circuit as the appliance as long as the two appliances are not together on the same circuit? Or does "separate" really mean "dedicated"? 20A dedicated for each appliance sounds like overkill and I'd like to put more recepticles on those circuits as I'm quickly using up space in the breaker box.

I know I could go down to city hall and ask them personally but that's a hassle and just thought I'd ask you guys if this is a code requirement. What is commonly done in this situation?

Thanks!



I know it used to be allowed on MWBC ( mulitwire branch circuit ) however a nice gotcha this part useally get quite few peoples off guard on this part is.,

A) either appalince shall not have more than 50% of circuit rating which it mean it can not be more than 7.5 amp on 15 amp circuit or 10 amp on 20 amp circuit.

B) I do not know what your local code may required a GFCI for garbage dispoal unit so that is kinda toss up on that part only your inspector will know the details.

And more and more dishwasher and garbage dispoal unit is getting more powerfull so the amp rating do creep up so a new good quality dishwasher can hit high as 12 amp so that will kill the deal with MWBC so that one reason why it have to be it own circuit ditto with garbage dispoal unit.

Now the other reason why I say seperated circuit due some of the dishwasher I know in state side can be cord et plug attachment or hard wired but the key issue is disconnecting means with cord and plug attachment that is not a issue when you work on the dishwasher all you have to do is unplug it. but hard wired verison you will need a lock out tab to keep prevent from the breaker being turn on.

The reason why lock out on the breaker due it is not in sight of breaker box.

Hope that help you with this part.

Merci,
Marc

sublime2 02-12-2013 02:41 AM

Separate lines but not dedicated.

k_buz 02-12-2013 09:23 AM

Read the OP. his inspection department is requiring separate 20 A dedicated circuits.

Stubbie 02-12-2013 12:00 PM

Quote:

Originally Posted by lmorsino (Post 1115451)
I'm renovating my kitchen, and on the permit, the building official notes that the dishwasher and food disposal unit

"must be on two separate circuits of 20A each"

Does the code allow me to hook up any other recepticles on the same circuit as the appliance as long as the two appliances are not together on the same circuit? Or does "separate" really mean "dedicated"? 20A dedicated for each appliance sounds like overkill and I'd like to put more recepticles on those circuits as I'm quickly using up space in the breaker box.

I know I could go down to city hall and ask them personally but that's a hassle and just thought I'd ask you guys if this is a code requirement. What is commonly done in this situation?

Thanks!

The NEC uses the term 'individual' branch circuit for dedicated or separate. As K Buz has mentioned you need a 20 amp branch circuit to each appliance .. nothing else can be on those circuits. It has become the norm in most areas of the country AFAIK.

lmorsino 02-12-2013 01:08 PM

Wow, thanks for all the helpful responses, gentlemen...I guess I will just wire it with two dedicated 20A circuits

sublime2 02-12-2013 01:25 PM

Quote:

Originally Posted by Stubbie (Post 1115697)

The NEC uses the term 'individual' branch circuit for dedicated or separate. As K Buz has mentioned you need a 20 amp branch circuit to each appliance .. nothing else can be on those circuits. It has become the norm in most areas of the country AFAIK.

What is the reasoning/thinking behind these appliances being on their own dedicated circuit?

diystephen 02-12-2013 03:09 PM

Quote:

Originally Posted by sublime2 (Post 1115759)
What is the reasoning/thinking behind these appliances being on their own dedicated circuit?

The potential amperage that they might draw.

lmorsino 02-12-2013 03:18 PM

If we're just talking about the "potential" amps they might draw, isn't that what circuit breakers are for? What is wrong with simply adding up the power needs of the two appliances and providing a circuit that can handle that much power?

Let's say the disposal draws 10A and the diswasher is rated at 8.5A. Why is a single 20A circuit not sufficient?

diystephen 02-12-2013 03:25 PM

Quote:

Originally Posted by lmorsino (Post 1115883)
If we're just talking about the "potential" amps they might draw, isn't that what circuit breakers are for? What is wrong with simply adding up the power needs of the two appliances and providing a circuit that can handle that much power?

Let's say the disposal draws 10A and the diswasher is rated at 8.5A. Why is a single 20A circuit not sufficient?

Because there are dishwashers and disposals that draw more than that. Disposals also draw more amperage when people (like my wife) shove too much crap in them :laughing: Circuit breakers aren't meant to be repeatedly tripped. This will also heat up the wiring, and can potentially damage it.

Then there's the fact that the inspector "said so." :jester:

lmorsino 02-12-2013 03:28 PM

So the real reason is to provide yet another layer of redundancy for people who don't understand how electricity works. At the expense of everyone else.

diystephen 02-12-2013 03:34 PM

Quote:

Originally Posted by lmorsino (Post 1115894)
So the real reason is to provide yet another layer of redundancy for people who don't understand how electricity works. At the expense of everyone else.

Electricity is theory; nobody really "knows" how it works :laughing:

Even those that have a good understanding of electricity wouldn't want a single 20A circuit for a dishwasher and disposal.

sublime2 02-12-2013 06:55 PM

Quote:

Originally Posted by diystephen (Post 1115898)

Electricity is theory; nobody really "knows" how it works :laughing:

Even those that have a good understanding of electricity wouldn't want a single 20A circuit for a dishwasher and disposal.

I'm not saying put both on one line.
Why can you not put anything else (receptacle) on the line.
Why dedicated?


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