Disp & Dishwasher on single 20A ckt?

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I often refer to the manufactures instructions when a contractor is resistant in excepting the validity of a code requirement. The international residential code was mentioned in this thread the IRC states that this code will be followed except if so doing violates the manufacture instructions. And it also states that a violation of the manufacture instructions is a violation of the IRC


R106.1.2 Manufacturer’s installation instructions. Manufacturer’s
installation instructions, as required by this code, shall be available on the job site at the time of
inspection

LISTED AND LISTING. Terms referring to equipment that
is shown in a list published by an approved testing agency qualified
and equipped for experimental testing and maintaining an
adequate periodic inspection of current productions and whose
listing states that the equipment complies with nationally recognized
standards when installed in accordance with the manufacturer’s
installation instructions

MANUFACTURER’S INSTALLATION INSTRUCTIONS.
Printed instructions included with equipment as part
of the conditions of listing and labeling.

R102.4 Referenced codes and standards. The codes and
standards referenced in this code shall be considered part of the
requirements of this code to the prescribed extent of each such
reference. Where differences occur between provisions of this
code and referenced codes and standards, the provisions of this
code shall apply.

Exception: Where enforcement of a code provision would
violate the conditions of the listing of the equipment or
appliance, the conditions of the listing and manufacturer’s
instructions shall apply.
 
Ragin Cajun said:
The owners are going to ask - says who? What code section tells us to also refer to appliance installation instructions?

BTW, I checked the instructions for three manufacturers of dishwashers, one diidn't address individual circuits, one only "recomended" it, but only good old GE under "Electrical Requirements" said there must be an individual branch circuit. Pardon my, but that's a crock! Adds an additional ~$100 per unit to the electrical installation costs. :rant:

Thanks,

RC
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is there a reason a different manufacture could not be specified
 
GoldDigger said:
As I said, a DW with a drum switch (timer) will almost certainly resume where it left off. Unless it had a safety circuit added like modern dryers.
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If digital DW clocks don't run on batteries, have similar power-supply limits of 100vac, as listed on digital TV, Computer, Monitor, and Printer nameplates, they may reset during voltage-drop events caused by disposer starts.

A 120vac 1/2 HP disposer locked-rotor start draws 60-Amps, Table 430.251(A), momentarily pulling 50ft of 12/2 down to 97vac.
 
ramsy said:
If digital DW clocks don't run on batteries, have similar power-supply limits of 100vac, as listed on digital TV, Computer, Monitor, and Printer nameplates, they may reset during voltage-drop events caused by disposer starts.

A 120vac 1/2 HP disposer locked-rotor start draws 60-Amps, Table 430.251(A), momentarily pulling 50ft of 12/2 down to 97vac.
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That's exactly it. Many elecs are quick to dismiss it with "you can't push 60A through 12! per NEC" when you talk about voltage drop in 12 AWG at 60A. Many computers have a worldwide power supply and they're designed to operate with steady input voltage down to 90v. They may not handle abrupt drop from 120v to 90v even if they can handle gradual drop.

Another thing that's sensitive to brown out is refrigeration compressor. If the brown out is long enough the motor's torque drops enough to stall. Motor doesn't have enough torque to start under load and cause it to trip on overload. It has to wait 5-10 minutes to restart.
 
ramsy said:
If digital DW clocks don't run on batteries, have similar power-supply limits of 100vac, as listed on digital TV, Computer, Monitor, and Printer nameplates, they may reset during voltage-drop events caused by disposer starts.

A 120vac 1/2 HP disposer locked-rotor start draws 60-Amps, Table 430.251(A), momentarily pulling 50ft of 12/2 down to 97vac.
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A worst case scenario 1/2 HP 115 volt motor may draw 58.8 amps according to the table.

The surge when energizing could still be more then that - but only for a few cycles, locked rotor is what it draws when the shaft is not turning and the magnetic fields are established.

I could see a disposer motor drawing 60 or more amps for a few cycles when first energized, but I bet most won't draw that much if the rotor is locked after the fields are established.

I think you will need at least 150 amps before you start to get into instantaneous trip range of a 20 amp circuit breaker.

What if the dishwasher with the digital control has a 1/2 hp motor?
 
At least in my house, the disposal is being run while the dishwasher is being loaded, not after you start running it.
 
After large gatherings I often run the DW and disposal at the same time. The plates, glasses, silverware will usually fill the dishwasher and we start the cycle. Then platters, pans, etc get washed by hand with the disposer running from start to finish. (when I do the clean-up)
 
kwired said:
I've never had a callback when they were on the same circuit, seems to be a reliable plan as well.
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Awesome

Yet the first time a inspector decides to enforce 110.3(B) and the manufactures directions for an individual branch circuit you will waste more money and time correcting it or fighting it than another circuit would have cost in the first place.

Another personal choice issue.
 
iwire said:
Awesome

Yet the first time a inspector decides to enforce 110.3(B) and the manufactures directions for an individual branch circuit you will waste more money and time correcting it or fighting it than another circuit would have cost in the first place.

Another personal choice issue.
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Until we get an inspector that is that nit picky - we are all happy. Once we get one that is that nit picky - we (as in a majority of the contractors he has to inspect for) likely will make life hard for him, it will have a cost but going along with him just lets him win. You may choose which individual battles to fight and which to surrender at times though. It has happened before.
 
kwired said:
Until we get an inspector that is that nit picky -
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Exactly so when you give advice based on your experience in an area you have told us time and time again that is not very diligent about inspections and enforcement that is not very helpful for those that live in places with tight inspections is it?
 
iwire said:
Exactly so when you give advice based on your experience in an area you have told us time and time again that is not very diligent about inspections and enforcement that is not very helpful for those that live in places with tight inspections is it?
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We don't like to be told what to do here, but do see it necessary for some things.

I'm sure big city people don't like to be told what to do either, but they don't seem to find it worth while to fight with "city hall" so to speak.

Surprisingly, the American Revolution started in your area:)
 
kwired said:
We don't like to be told what to do here, but do see it necessary for some things.
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Show me an area that does. :)

I'm sure big city people don't like to be told what to do either, but they don't seem to find it worth while to fight with "city hall" so to speak.
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Fight what? enforcement of the adopted rules? :?

The NEC is adopted in your area is it not?


Honestly I do understand areas have different levels of enforcement, based on what I read on these forums I would rate my own area a C.

Very lax here on somethings, a lot of work gets done without permits. When permits are pulled very little detail is needed. When I read some inspectors post here I quickly realize if I moved to their area I would be failing some inspections till I stepped up my game. (An example, this area is pretty lax about cable support close to the box)
 
iwire said:
Very lax here on somethings, a lot of work gets done without permits. When permits are pulled very little detail is needed. When I read some inspectors post here I quickly realize if I moved to their area I would be failing some inspections till I stepped up my game. (An example, this area is pretty lax about cable support close to the box)
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A lot of the same here. We get some heat from customers in general as electricians as electrical gets inspected, many other aspects of most projects do not. Buildings with public access do get a look at from the State Fire Marshal, though they are not too strict either compared to some places, but sometimes a customer is not expecting the visit from the Fire Marshal and then finds out they do need to do some things differently.
 
iwire said:
Awesome

Yet the first time a inspector decides to enforce 110.3(B) and the manufactures directions for an individual branch circuit you will waste more money and time correcting it or fighting it than another circuit would have cost in the first place.

Another personal choice issue.
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Like that is going to happen. :roll::happyno:
 
peter d said:
Like that is going to happen. :roll::happyno:
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Yes Pete it does happen in some areas, I know you have read those types of posts on these forums just like I have.

Just like some areas require everything to be listed, different areas different expectations.
 
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