Two circuits - one box

[PassnThru]

Replaced my garbage disposal this weekend and it got me thinking about my power under the sink. I currently have a metal junction box mounted to the back of the sink cabinet. Since I have a dishwasher and a garbage disposal I have two feeds into this box. The potential issue is that the feeds are from separate but side by side breakers (240 potential) from the main panel. The feeds are 12/2, not 12/3 so they do not share a neutral. I didn't look in the box this weekend but as I recall the circuits are treated separately in the box - i.e. the neutrals are not joined in the box - only the grounds. I was concerned about code and safety - I could see someone potentially only turning one breaker off to work in the box - although it should be obvious from appearances that there are two separate circuits. Is this really an isssue? Do I need separate boxes for each circuit? Should it just be labeled? Or is everything OK as is?

 

[mrb]

its ok to have more than one circuit in a box. make sure the neutrals are kept seperate. If the two circuits are on a common yoke (split duplex) then the breakers need a handle tie.

 

[PassnThru]

its ok to have more than one circuit in a box. make sure the neutrals are kept seperate. If the two circuits are on a common yoke (split duplex) then the breakers need a handle tie.

Ok - that's good. There is no receptacle in the box - they go out directly to the dishwasher and the garbage disposal (which is direct wired).
Thanks.

 

[walrus]

Ok - that's good. There is no receptacle in the box - they go out directly to the dishwasher and the garbage disposal (which is direct wired).
Thanks.

Isn't there a requirement for a disconnecting means in sight of the equipment?

 

[oleguy]

dish washers are not supposed to be hardwired.also trash compactors,disposals.cord and plug only.422.16(b)(2).

 

[mooman]

Does not say HAS to be cord and plug only

NEC 422.16 (b) (2) says this.....



(2) Built-in Dishwashers and Trash Compactors.
Built-in
dishwashers and trash compactors shall be permitted to be
cord-and-plug connected with a flexible cord identified as
suitable for the purpose in the installation instructions of
the appliance manufacturer where all of the following conditions
are met.
(1) The flexible cord shall be terminated with a groundingtype
attachment plug.


Exception: A listed dishwasher or trash compactor distinctly
marked to identify it as protected by a system of double insulation,
or its equivalent, shall not be required to be terminated
with a grounding-type attachment plug.
(2) The length of the cord shall be 0.9 m to 1.2 m (3 ft to
4 ft) measured from the face of the attachment plug to
the plane of the rear of the appliance.
(3) Receptacles shall be located to avoid physical damage
to the flexible cord.
(4) The receptacle shall be located in the space occupied
by the appliance or adjacent thereto.
(5) The receptacle shall be accessible

 

[walrus]

I have a septic so no garbage disposal, but aren't they controlled by a toggle on the wall? Wouldn't that be the disconnect? What about a permanently affixed lockout device on the breaker?

 

[PassnThru]

Thinking about things today (I'm at work) I recall four cables coming in - going out of the box. I believe my earlier assessment was wrong - one of the wires is probably the switch leg for the disposal. Which would mean that there is one supply - a 12/3 which means a shared neutral. I know for a fact that it feeds from two single pole breakers. I'll verify later - don't know if that changes things or not.
I've never seen a built-in dishwasher with a plug but I haven't seen that many. I've seen a disposal with a plug but I assumed it was a convenience thing - not a code thing.

 

[walrus]

Thinking about things today (I'm at work) I recall four cables coming in - going out of the box. I believe my earlier assessment was wrong - one of the wires is probably the switch leg for the disposal. Which would mean that there is one supply - a 12/3 which means a shared neutral. I know for a fact that it feeds from two single pole breakers. I'll verify later - don't know if that changes things or not.
I've never seen a built-in dishwasher with a plug but I haven't seen that many. I've seen a disposal with a plug but I assumed it was a convenience thing - not a code thing.

If it was installed before 2008 code was accepted by your local, a MWBC(12/3) could be on 2 separate breakers

 

[Falcon67]

I wired ours like that - two separate runs to the area into one box. Left outlet is switched for the disposal and the right is always hot for the dishwasher. Separate circuits, all the copper tied together. So what on the copper in my mind - ground is ground. Both appliances use cord and plug for easy service. If the disposal jams, why wander out to the breaker box. I put the dishwasher on a cord so I could put a surge protector on the dishwasher. Every damn appliance needs one now - stove, clothes washer, etc.

 

[oleguy]

Does not say HAS to be cord and plug only

NEC 422.16 (b) (2) says this.....



(2) Built-in Dishwashers and Trash Compactors.
Built-in
dishwashers and trash compactors shall be permitted to be
cord-and-plug connected with a flexible cord identified as
suitable for the purpose in the installation instructions of
the appliance manufacturer where all of the following conditions
are met.
(1) The flexible cord shall be terminated with a groundingtype
attachment plug.


Exception: A listed dishwasher or trash compactor distinctly
marked to identify it as protected by a system of double insulation,
or its equivalent, shall not be required to be terminated
with a grounding-type attachment plug.
(2) The length of the cord shall be 0.9 m to 1.2 m (3 ft to
4 ft) measured from the face of the attachment plug to
the plane of the rear of the appliance.
(3) Receptacles shall be located to avoid physical damage
to the flexible cord.
(4) The receptacle shall be located in the space occupied
by the appliance or adjacent thereto.
(5) The receptacle shall be accessible

you are right but it is not a good idea to hard wire those appliances.but i guess do what you want to do.I have wired houses for 20 years and never hard wired those.

 

[PassnThru]

Thinking about things today (I'm at work) I recall four cables coming in - going out of the box. I believe my earlier assessment was wrong - one of the wires is probably the switch leg for the disposal. Which would mean that there is one supply - a 12/3 which means a shared neutral. I know for a fact that it feeds from two single pole breakers. I'll verify later - don't know if that changes things or not.
I've never seen a built-in dishwasher with a plug but I haven't seen that many. I've seen a disposal with a plug but I assumed it was a convenience thing - not a code thing.

OK - confirmed that it was a 12/3 supply. It does all predate 2008. No outlet involved - I think code wise it is OK. Would it be prudent to label the box as containing 2 circuits (again - 240 potential) for anyone else that might dig into it? What does code require now considering the situation? A handle tie? A double pole breaker?
I'm personally fine with it but I'd like to learn and would possibly work on it if there was a good reason.
While I'm on the subject, I wired the new disposal with the existing romex. I'm guessing that may not be allowed by code anymore since no one seems to want romex exposed any any fashion anymore.

 

[MrMark]

Yes, double pole breaker or handle tie. I would label it at least.