Connecting 2 to 3 Conductors

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Old 02-16-14, 10:04 AM
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Connecting 2 to 3 Conductors

I am assisting a son redo a kitchen in a house that is about 50 years old and I have some questions about the electrical connection to the dishwasher and disposal. There is a two conductor cable (no ground) to a switch box. The two conductor cable is spliced into a three conductor armored cable in the switch box. The splice is soldered and taped.

The armored cable connects at the bottom of the switch box and exits the wall at that point. The cable runs along the wall for 3 or 4 feet to a junction box that was mounted on the wall. A short length of armored cable runs from the junction box to the disposal and a short piece of Romex looking wire runs from the junction box to the dishwasher.

He would like to clean this up as much as possible, especially the armored cable that runs along the wall. I have some thought on how to proceed; looking for input the safest, code compliant (as far as possible in a 50 year old house) way to do this. Most of my questions are about whether I can use the existing connections in the switch box or should I replace with new.

Can I route the armored cable from the switch box to the junction box inside the wall? Could I use the existing solder splices? The solder is well flowed and appear to be very good. Of course I would wrap them in new tape. I am guessing I would need to drill 7/8 or 1 inch holes in the studs to route the cable thru the wall. Can I drill holes that large thru the studs? Is there something I am overlooking if I go this route?
Another possibility is to replace the armored cable with new 3 conductor cable. If I do this can I use wire nuts to connect the 2 conductor cable to the 3 conductor? Can I make the connection in the switch box?

We are considering replacing the junction box, where the cables are routed to the disposal and dishwasher, with a wall receptacle because it seems that new dishwashers and disposals are equipped with plugs. Any thoughts on this? Is there a common practice to make either the upper or lower receptacle switched?

I apologize for being so long. Thanks for any input you can provide.
 
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Old 02-16-14, 12:06 PM
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Disposal Dishwasher

We are considering replacing the junction box, where the cables are routed to the disposal and dishwasher, with a wall receptacle because it seems that new dishwashers and disposals are equipped with plugs. Any thoughts on this? Is there a common practice to make either the upper or lower receptacle switched?
Here is the typical split-wired receptacle under the sink with switch above the counter. This provides a separate circuit for the disposal and the dishwasher.
Name:  Disposal Dishwasher Drwg.jpg
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Old 02-16-14, 12:32 PM
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Nice drawing BAHTAH!

Seriously, very good clear and concise.

But to add to what you have said, some areas require adherence to the latest code. So a piece of 12/3 would be required between the receptacle and the switch with the white staying a neutral wire and capped with a wirenut at the switch. The red wire in that 12/3 taking it's place in your diagram.
Personally I would not have used the 12/3 there, but some laws we don't agree with still have to be followed.

The switch should be rated for 20 amps. As for the switch, about two weeks ago I had to replace a 15 amp rated switch that was on a 20 amp circuit. It was blown open.

One could use a double 20 amp breaker to insure that the feeds are taken from both sides of the 240 available, but two breakers with separate handles placed next to each other in the panel box might be better.

Cordially,
Gerry
 
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Old 02-16-14, 01:05 PM
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Let me clarify a little. Can I not use the existing circuit down to the junction box, replacing only the junction box with a wall receptacle? Or can I not use the existing circuit at least to the switch box?
 
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Old 02-16-14, 01:12 PM
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If the old cable is in good shape AND has a grounding means you could re-use it. Otherwise I would remove it and run a new grounded circuit. The instructions will call for a grounded circuit.
 
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Old 02-16-14, 02:42 PM
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> Can I not use the existing circuit down to the junction box, replacing
> only the junction box with a wall receptacle?

If I understand your question, a 12/3 cable from breaker box routes to the switch box. Then another cable from that switch routes to both wall receptacles?

Then a 12/2 wire (in bahtah's excellent picture) from switch box to receptacle box must be changed to 12/3.

BTW, not only must the switch be 20 amps (not 15 amp) type. Receptacle should also be 20 amp type (that accept 15 or 20 amps plugs). That assumes each receptacle is the only receptacle powered by that circuit breaker. Mostly only semantics; not reallly a human safety issue.

The term junction box is vague and subject to confusion. Better is to Bahtah's wording to describe each box and cable: breaker, panel, 12/3, 12/2, receptacle, and switch (he did not use 'switch' but that should be obvious).
 
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Old 02-16-14, 02:46 PM
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connecting 2 to 3 conductor

gerry_d, thanks for pointing out my mistake. I will have to update my drawing. Thanks Again.... good to have people on here that are up to speed.
 
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Old 02-16-14, 05:42 PM
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Connecting 2 to 3 conductors

Name:  Disposal Dishwasher Drwg.jpg
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Here is corrected drawing... Thanks for the catch!
 
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Old 02-16-14, 07:03 PM
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The switch does not need to be 20 amp rated. It needs to be sized for the load it is switching, not the circuit size.
 

Last edited by pcboss; 02-17-14 at 10:59 AM. Reason: removed incorrect info
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Old 02-17-14, 10:30 AM
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Connecting 2 to 3 conductors

I was thinking since the receptacle was split that it then became two individual receptacles each on a 20 amp circuit. Looks like the definition of a receptacle does not take the separation into consideration. Thanks pcboss for pointing that out! Hopefully the third time is the charm.

Mod Note: the OP was correct that the receptacle is now a simplex and needs to be circuit rated.

Attachment 26886
 

Last edited by pcboss; 02-17-14 at 11:00 AM.
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Old 02-17-14, 10:58 AM
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Sorry, you were correct since there is only one receptacle per circuit. My error. I will correct my post above.
 
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Old 02-17-14, 10:00 PM
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Thanks Everyone

Thank you all for your responses.

My son had someone with a lot more knowledge to look at the circuit. He said that the the existing circuit (12/2 with ground) from the breaker box to the switch box was good. He wired 2 receptacles with 12/2 wire. One is switched for the disposal and the other un-switched for the dishwasher. He installed a GFI receptacle in the always hot leg.

If I understand the comments correctly the switch should be 20 amps. Is that correct. I am not sure what he installed so I need to check that.
 
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Old 02-17-14, 10:34 PM
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But you needed only one duplex receptacle not two and you didn't need a GFCI. However what he did is not wrong. The switch should be horsepower not tungsten rated and should equal or exceed the horsepower of the garbage disposal. Usually though a 15 amp tungsten rated light switch is fine.
 
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