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#94719 - 07/05/05 10:41 PM disposer/dish circuit
watersparkfalls Offline
Member

Registered: 03/08/05
Posts: 210
Loc: Washington...Not DC
i want to know if anybody can help me calculate if i can put a 1/2 HP disposer motor and a dishwasher that draws a nameplate or 9.1 amps on a 20 amp circuit.

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#94720 - 07/06/05 09:39 AM Re: disposer/dish circuit
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
Nominal FLA on a 1/2 HP motor is 9.8a (plus 25%) added to 9.1a seems to be too much for a multiple motor load.
If you are cord and plug connected they each do represent less than 50% of circuit ampacity so it might be "hold your nose" legal. I have seen this go both ways but the preferable solution is a multiwire circuit with 2 phases feeding the duplex.
_________________________
Greg Fretwell

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#94721 - 07/06/05 11:12 PM Re: disposer/dish circuit
watersparkfalls Offline
Member

Registered: 03/08/05
Posts: 210
Loc: Washington...Not DC
thanks gf i just wondered if possible...
could you elaborate on the 50% since cord connected dishwashers are feasible and do provide disconnecting means for motor.

h2o

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#94722 - 07/07/05 09:39 AM Re: disposer/dish circuit
gfretwell Offline

Member

Registered: 07/20/04
Posts: 9045
Loc: Estero,Fl,usa
It all gets down to how you read
210.23(A)(2) Utilization Equipment Fastened in Place. The total rating of utilization equipment fastened in place, other than luminaires (lighting fixtures), shall not exceed 50 percent of the branch-circuit ampere rating where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.

Most inspectors would say all fixed in place equipment must be less than 50% but I have seen this stretched to say any one piece can't exceed 50%, particularly on an intermittant load like a disposal.
Vote me for "all".
_________________________
Greg Fretwell

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#94723 - 07/07/05 07:03 PM Re: disposer/dish circuit
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
One caution here....look at the FLA on the disposal, and not the "horsepower" rating. I have seen a lot of inflated "horsepower ratings" over the years.

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#94724 - 07/12/05 06:46 PM Re: disposer/dish circuit
Larry Fine Offline
Member

Registered: 02/18/05
Posts: 684
Loc: Richmond, VA
"...lighting units (or) cord-and-plug-connected utilization equipment not fastened in place..."

Neither describe either a dishwasher or a disposer, so 210.23(A)(2) doesn't apply.

I routinely place both of these on a 20-amp circuit. A disposer is probably the epitome of an intermittent load.
_________________________
Larry Fine
Fine Electric Co.
fineelectricco.com

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#94725 - 07/12/05 06:55 PM Re: disposer/dish circuit
Larry Fine Offline
Member

Registered: 02/18/05
Posts: 684
Loc: Richmond, VA
According to Insinkerator specs, the 1/2HP Badger 5 has an average current draw of 6.9A.
http://www.insinkerator.com/pdf/badger5.PDF
_________________________
Larry Fine
Fine Electric Co.
fineelectricco.com

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#94726 - 08/10/05 06:27 AM Re: disposer/dish circuit
dlhoule Offline
Member

Registered: 04/28/05
Posts: 71
Loc: Saline, MI 48197
Good subject. I have been told that they make a 3 way switch that can be used in these applications. One position for dishwasher and other for disposal. Now having said that I personally have not seen one. Do they make them?

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#94727 - 08/10/05 07:23 AM Re: disposer/dish circuit
BobH Offline
Member

Registered: 10/16/04
Posts: 134
Loc: Newfane, N.Y USA
Any 3-way rated for the load would work.

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#94728 - 08/10/05 02:43 PM Re: disposer/dish circuit
Ryan_J Offline
Moderator

Registered: 08/19/03
Posts: 1355
Loc: West Jordan, Utah, USA
I am moving this to the NEC section.
_________________________
Ryan Jackson,
Salt Lake City

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