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#154392 07/06/05 01:41 AM
Joined: Mar 2005
Posts: 237
Member
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.

Building Codes & Related References
#154393 07/06/05 12:39 PM
Joined: Jul 2004
Posts: 9,667
Likes: 5
G
Member
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
#154394 07/07/05 02:12 AM
Joined: Mar 2005
Posts: 237
Member
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

#154395 07/07/05 12:39 PM
Joined: Jul 2004
Posts: 9,667
Likes: 5
G
Member
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
#154396 07/07/05 10:03 PM
Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
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.

#154397 07/12/05 09:46 PM
Joined: Feb 2005
Posts: 693
L
Member
"...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
#154398 07/12/05 09:55 PM
Joined: Feb 2005
Posts: 693
L
Member
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
#154399 08/10/05 09:27 AM
Joined: Apr 2005
Posts: 73
D
Member
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?

#154400 08/10/05 10:23 AM
Joined: Oct 2004
Posts: 135
B
Member
Any 3-way rated for the load would work.

#154401 08/10/05 05:43 PM
Joined: Aug 2003
Posts: 1,374
R
Moderator
I am moving this to the NEC section.


Ryan Jackson,
Salt Lake City

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