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Discussion Starter · #1 ·
We are putting in 2 garbage disposals into 2 sinks relatively close to each other. Amp loads are 6.9 and 8.1 which equals 15, can I run them both off a single 20 amp circuit, or should I run dediated circuits, and if dedicated, I would assume 15 amp circuits would be ok. NEC is in effect; would one circuit satisfy code?
Thanks.
 

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Lic Electrical Inspector
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We are putting in 2 garbage disposals into 2 sinks relatively close to each other. Amp loads are 6.9 and 8.1 which equals 15, can I run them both off a single 20 amp circuit, or should I run dediated circuits, and if dedicated, I would assume 15 amp circuits would be ok. NEC is in effect; would one circuit satisfy code?
Thanks.
What are the horsepowers?
 

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Lic Electrical Inspector
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3/4 hp & 1/2 hp. They are Isinkerators, ones a 5 the other a 5xp.
The 3/4HP will need a dedicated #14 circuit with a 35A breaker.

The 1/2HP will need a dedicated #14 cicuit with a 25A breaker.

They are motors and the requirements are specific. If you want I would be happy to provide the calculations for each motor.
 

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Master Electrician
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The 3/4HP will need a dedicated #14 circuit with a 35A breaker.

The 1/2HP will need a dedicated #14 cicuit with a 25A breaker.

They are motors and the requirements are specific. If you want I would be happy to provide the calculations for each motor.
That is TOTAL BS. You do not calculate residential appliance motor circuits using motor calculations.
Read NEC 430.6 in totality. Especially the exceptions.
 

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We are putting in 2 garbage disposals into 2 sinks relatively close to each other. Amp loads are 6.9 and 8.1 which equals 15, can I run them both off a single 20 amp circuit, or should I run dediated circuits, and if dedicated, I would assume 15 amp circuits would be ok. NEC is in effect; would one circuit satisfy code?
Thanks.
If you want to avoid problems and comply with the appliance instructions, run individual 15 amp circuits to each GD.
 

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That is TOTAL BS. You do not calculate residential appliance motor circuits using motor calculations.
Read NEC 430.6 in totality. Especially the exceptions.

Thank you. I knew this was BS, but I was waiting for a real electrician to respond.

In my 30 years of industrial, commercial and multi-family construction, I have never seen a disposal protected with anything other than a 15 or 20 circuit breaker. The statement by our "Inspector" is ludicrous. Now you have residential wiring protected by a much bigger breaker than it safely should be.

This is the danger with so many of these sites, you get some "experts" who claim to be "State Electrical Inspectors" and some poor fool will listen to them

430.6 (A) (1) exception #3 - correct?

electures: You're a fool if as a inspector you can't tell someone how to safely wire a garbage disposal
 

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Yeah, nobody sizes residential motor-based appliance circuits that way. Nor is there any good reason to. It wouldn't even be code compliant to use those breaker/conductor combinations if these disposals are cord-and-plug connected.

I'd install one 20A circuit for both of them. I'm not aware of any requirement that garbage disposals have a dedicated circuit. You can even add other receptacles on that circuit if you want to get more use out of it. However, you can't count it as one of the "small appliance circuits" required in a kitchen.

EDIT: brric makes a good point - the disposal instructions may call for a dedicated circuit to each.
 
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Discussion Starter · #9 ·
Thanks for all the input,
"It wouldn't even be code compliant to use those breaker/conductor combinations if these disposals are cord-and-plug connected"
That did make me scratch my head, but what the heck do I know.
And when in doubt, read the instructions.
My panel is getting a little crowded, and I though maybe I could get away with one 20 instead of 2 15's.
I appreciate eveyone's input.
 

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Do you know if your panel can accept twin/tandem breakers? Then it would only use one breaker slot.
 

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I think in Canada we can put one garbage disposal on the same circuit as a dishwasher, but im not sure about putting 2 disposal's on the same circuit.
 

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430.6 (A)(1) 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.

They both could be run off a single 20 amp circuit.
 

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Discussion Starter · #13 ·
Thank you, NJMarine, for a definitive answer.
And, SD515, thanks for the input, my panel does accept the smaller breakers, and I will be using some. Still trying to conserve a circuit if I really don't need the extra one.
Thanks all.
 

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As a couple others have mentioned…run ‘em both off a 20A circuit, them only. Besides, when are you going to be using them at the same time? Even then, the duration probably wouldn’t be very long.
 

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A "Handy Husband"
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brric,

I think you teed off electures, he has not made another post since you called him on the OCPD requirements for the garbage disposers.
 
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Lic Electrical Inspector
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That is TOTAL BS. You do not calculate residential appliance motor circuits using motor calculations.
Read NEC 430.6 in totality. Especially the exceptions.
Sorry for the delayed response. Just got back from vacation.

Where exactly in the NEC is there any kind of exceptions for residential appliance motor circuits?


422.3 Other Articles.
The requirements of Article 430 shall apply to the installation of motor-operated appliances, and the requirements of Article 440 shall apply to the installation
of appliances containing a hermetic refrigerant motor-compressor(s), except as specifically amended in this article.

As for 430.6(A)(1) exceptions lets take a look at exception 3;

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 branchcircuit
conductors, the controller, the branch-circuit shortcircuit and ground-fault protection, and any separate overload protection.


Article 100 definitions reads;

Appliance. Utilization equipment, generally other than industrial, that is normally built in standardized sizes or types and is installed or connected as a unit to perform one or
more functions such asclothes washing, air conditioning, food mixing, deep frying, and so forth.


A garbage disposal is a purely a motor so exception 3 does not apply.

Now, just for the sake of arguement (and I know there will be) lets say that exception 3 does apply.


Exception No. 3: For alisted 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 branchcircuit
conductors, the controller, the branch-circuit shortcircuit and ground-fault protection, and any separate overload protection.

Looking at the information provided by the OP;

Amp loads are 6.9 and 8.1

Insinkerator 5
6.9 x 125% = 8.625 amps. #14 awg is needed.

6.9 x 250% = 17.5. A 20 amp breaker can be used.

Insinkerator 5X
8.1 x 125% = 10.125. #14 awg is needed.

8.1 x 250% = 20.25. A 25 amp breaker can be used.

However, since exception 3 does not apply my original post is correct.

On a side note, if I encountered this on the job I would run seperate #14 circuits with 15 amp breakers on each. If the larger motor tripped the breaker during use, a larger breaker can be used.
 

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Lic Electrical Inspector
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Yeah, nobody sizes residential motor-based appliance circuits that way. Nor is there any good reason to. It wouldn't even be code compliant to use those breaker/conductor combinations if these disposals are cord-and-plug connected.

I'd install one 20A circuit for both of them. I'm not aware of any requirement that garbage disposals have a dedicated circuit. You can even add other receptacles on that circuit if you want to get more use out of it. However, you can't count it as one of the "small appliance circuits" required in a kitchen.

EDIT: brric makes a good point - the disposal instructions may call for a dedicated circuit to each.
Putting both disposals on one circuit is a violation of 430.53(A).
 

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Lic Electrical Inspector
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Thank you. I knew this was BS, but I was waiting for a real electrician to respond.

In my 30 years of industrial, commercial and multi-family construction, I have never seen a disposal protected with anything other than a 15 or 20 circuit breaker. The statement by our "Inspector" is ludicrous. Now you have residential wiring protected by a much bigger breaker than it safely should be.

This is the danger with so many of these sites, you get some "experts" who claim to be "State Electrical Inspectors" and some poor fool will listen to them


electures: You're a fool if as a inspector you can't tell someone how to safely wire a garbage disposal
430.6 (A) (1) exception #3 - correct?

Incorrect. Try reading the NEC.
 

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Lic Electrical Inspector
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430.6 (A)(1) 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.

They both could be run off a single 20 amp circuit.[/quote]



Putting them both on one circuit is a violation of 430.53(A).
 
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