Island Cooktop

[West_Tex]

I have an existing kitchen island with a cooktop with 30 amp service and 10/3 running to it from my box in the garage. The supply wires run through the bottom of the island, through what appears 1/2 PVC in the slab, up to the attic behind my kitchen cabinets, then drops to the box in the garage. Also coming through the same opening in the island is a 12/3 to supply power to the outlets.

I am going to be upgrading my cooktop and the new unit specs out at 40 amps. I would like to run 8/3 wire for the new cooktop, but it will not fit through the existing raceway. At the bottom of the island is a downdraft vent that pretty much parallels the existing conduit run. The vent extends all the way to the roof through the attic. I capped the downdraft years ago because the island no longer has a downdraft, ie the vent is not being used for anything. There is plenty of room in the vent for any type of wire or conduit. The question is can I use the abandoned vent to run my 8/3 through the slab, then come out in the attic and complete my run to the electrical box in my garage?

Any replies would be appreciated. This is my first post but have learned tons on this forum lurking through the years.

 

[WorthFlorida]

I should be Ok. Normally, you're not allow to run wire inside a working air duct for never wanting to spread any fire or smoke from an electrical caused fire and a few more items. Two thing to do would be besure both ends are capped off so in the future one decides to use this vent to install a downdraft it would be difficult to do and not allow it to feed air or spread smoke in the event of a fire. Also, ground (green wire) the metal ductwork. Should a bare hot wire touch the metal ductwork you want the breaker to trip. Without a ground the entire duct could be hot and pose a fire and shock hazard. Do use metallic cable or conduit. There be no chance of shafeing or any sharp corner cutting into the the cable.

Your existing range may only have three wires, all new 220v appliances and code requires four wire. L1 (BLK), L2 (Red), neutral (WHT), ground (Green in conduit, usually bare wire in pre wired MC cable). "Do use 8/3 with ground." If you cannot get copper wire, then you need to use #6 aluminum wire.

It is always best to contact your local building department and ask the same question. To play it safe do pull a electrical permit. You can still do the work yourself as long you are living in the home. After a passed inspection you'll feel better knowing the work was performed correctly. If your doing a kitchen remodel and you have an old home, two 20 amp circuits are required for the countertops but since you did mentioned that the island has a 20a circuit for the outlets you're probably OK

If you cannot use this old vent this is another solution but you'll need to get a new floor. My friend had an island added to her total remodeled kitchen and to satisfy the electrical requirement, a grove was cut in the concrete slab, conduit was added. The cut was then mudded over when the floor tile was laid down.