What size circuit?

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czarnrob

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3/4hp Garbage Disposal.
Dishwasher = 7.8 amps.

What size circuit can these loads be put on? & Can they both be put on the same circuit?

If yes-why (what code section)?
If no-why (what code section)?
 
A 20A circuit should be more than adequate. 20A @ 80% = 16A. I figure you would be at about 13A at full load.
 
load

load

are garbage dispoal motors rated differently ? 430.248 shows 3/4 hp at 13.8 amps. spells overloaded to me.
 
Most manufacturers require a seperate circuit for their dishwasher. I have found that following the manufacturers instructions can eliminate a lot of hassles if something is to go wrong. 110.3(B) Installation and use.
 
augie47 said:
are garbage dispoal motors rated differently ? 430.248 shows 3/4 hp at 13.8 amps. spells overloaded to me.
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I'd be willing to bet that the 3/4 HP rating is inflated, and the actual label states a much lower amperage.

Have a clamp-on ammeter handy?
 
LarryFine said:
I'd be willing to bet that the 3/4 HP rating is inflated, and the actual label states a much lower amperage.

Have a clamp-on ammeter handy?
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Larry, aren't we required to use the NEC rating when we size the conductors for motors (in lieu of the nameplate)?
 
brichter said:
I'm confused. Whay would 80% have anything to dowith it. It is not a continuous load.
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A continuous load would require a circuit rated at 125% of the calculated load. The 80% is the maximum a circuit should be loaded under normal conditions.
 
augie47 said:
are garbage dispoal motors rated differently ? 430.248 shows 3/4 hp at 13.8 amps. spells overloaded to me.
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I checked out a kitchen aide disposal 3/4 hp and it was rated about 7 amps

m73214 said:
A continuous load would require a circuit rated at 125% of the calculated load. The 80% is the maximum a circuit should be loaded under normal conditions.
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I don't believe this is true. You could load a 200 amp service to 195 amps if you wanted as long as it wasn't continuous.

A disposal is on for 10 seconds at most and maybe the dishwasher is on at the same time.
 
hardworkingstiff said:
Larry, aren't we required to use the NEC rating when we size the conductors for motors (in lieu of the nameplate)?
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Exception No. 3: For a listed motor-operated appliance that is marked with both motor horsepower and full-load current, the motor full-load current marked on the nameplate of the appliance shall be used instead of the horsepower rating on the appliance nameplate to determine the ampacity or rating of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and any separate overload protection.
 
l3city said:
:smile: check NEC 210.21(B)(2)
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Since a duplex is two receptacles either half of the duplex could supply the load as listed in that table.
 
Mike,

Exception No. 3: For a listed motor-operated appliance that is marked with both motor horsepower and full-load current, the motor full-load current marked on the nameplate of the appliance shall be used instead of the horsepower rating on the appliance nameplate to determine the ampacity or rating of the disconnecting means, the branch-circuit conductors, the controller, the branch-circuit short-circuit and ground-fault protection, and any separate overload protection.
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Is that the difference between the "advertised" amperage to Suzie homemaker vs the reality on the nameplate? Seems to be the hype in a lot of marketing.
 
Dennis Alwon said:
I don't believe this is true. You could load a 200 amp service to 195 amps if you wanted as long as it wasn't continuous.

.
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After reading 210.23, I agree with you Dennis however I try to stay at the 80% load range on all of my lighting circuits as a design choice. As far as receptacle circuits go, who knows what will be plugged in?
 
I don't think it will get any deeper than 110.3(b). Find me a spec sheet for a dishwasher that does not require an individual branch circuit , then, I'm sure we will beat almost to death , the pertaining articles.
 
Most of the city's in my area want seperate circuits for both. AHJ issue. On a side note I am working on a house right now where we have 5 circuits in the kitchen just for dishwashers and garbage disposals. Big kitchen.
 
LarryFine said:
I'd be willing to bet that the 3/4 HP rating is inflated, and the actual label states a much lower amperage.

Have a clamp-on ammeter handy?
Click to expand...
I don't disagree with anything, but would like to add that series wound motors, with brushes, behave far differently from the "induction" motors listed in the table. I don't THINK the typical inrush exists at all.

The disposer motor runs at greater than 3600 rpm and is one of those series motors that is closer to a DC than AC motor in performance; indeed, I'd bet it will run on DC.

I wonder if there is any other "mounted in place" motor that is over 3600 rpm? Installed vacuum systems are a probability.
 
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