I am doing more research on this, and I need to clarify that the cooktop is 3-wire. My junction box wires are 4-wire.

I am mystified why the white and ground wires are connected together.

Usually called a "false ground" and usually done to get the ground on the receptacle when there is no actual ground wire ran to the box (or box itself grounded though conduit). Not correct anyway, might even be safer to just not have the ground connected at all?

" A bootleg ground is an electrical ground that is wired from
the neutral side of a receptacle or light fixture in an older 2-wire home. This
essentially connects the neutral side of the receptacle to the casing of an
appliance or lamp. It can be a hazard because the neutral wire is a
current-carrying conductor. Bootleg grounding is illegal and against code in many places "

I doubt very seriously that h82FAIL's "false ground" or "bootleg gorund" has anything to do with this situation. If there is no ground at the box it is illegal, improper, and unsafe to wire up a grounded receptacle to the neutral. If the box is grounded via the conduit, then it's not a "FALSE GROUND" or anything else, but a legal way of providing a ground. In this case you can connect the ground on the receptacle to the box or conduit by one of the approved means (terminal on a bushing or tapped hole in the box).

In this case it appears the cooktop only has two hots and a ground wire, then it would appear it needs no neutral connection at all and the neutral in the box should be left unconnected. Since this is a dedicated circuit and there's no neutral at the device it's not really a safety concern, but it is wrong.

HOWEVER before dismissing this as a non-problem, check very carefully that there is NOT INDEED a neutral needed for the cooktop. Some stoves have four terminals that allow the GROUND and NEUTRAL to be connected together for installation on GRANDFATHERED three wire circuits (an exemption in the code allows these to use the grounded (i.e. neutral) conductor to ground the appliance.
In this case, you need to remove the jumper and wire up the grounds and neutrals separately.

EEK! No this house is only 10 years old, so surely no need for bootleg ground!

From the junction box the white AND bare copper wire are connected to the cooktop ground. Again, both old and new cooktop are 3 wire which I now learn means 240v only (no 120v used).

From what I have read, the white wire should have been capped off and not used. The old cooktop was original to this production-built house, so I assume a licensed electrician was involved in the existing wiring connections.

Thus, I was going to duplicate the original wiring, but it makes no sense to me. What was the idea behind it? I am keen to learn but if I need a pro I will call one.

PS-- New Bosch InductionCooktop is aluminum wiring (Old Jenn-Air induction radiant hybrid was copper).I am reading I need to be sure to use Al/Cu connectors and no-ox lube. I thought aluminum was bad for wiring!

The Bosch induction cooktop is indeed a 208/240 ONLY device. If you read the instructions that come with it, it is clear that there are only the L1 and L2 (hot lines) and a ground. No white wire should be connected.

There are no ALUMINUM wires in this device. The silver color you see is "tinning" (a light layer of a non-aluminum alloy) over the copper to protect it.

Thank you everyone for clarifying all this! I will simply cap off neutral wire and I am happy to hear I don't need to buy special connectors, etc.

I guess it was "old school" to connect neutral and ground at appliance, but what I have read it is now not to code.

No, it was old school to not have the ground at all and possibly connect the appliance ground and neutral together.

It has never *EVER* been proper to connect the the ground and neutral of a four wire circuit together. Some moron wired your cooktop originally.

Thank you everyone! Cooktop works great, and boy does this thing boil water fast!

Yeah, love those inductions. The other trick if you are going to cook something that splatters is to line the entire cooktop with newspaper. Put the pan on top and cook. THen pick the whole mess up and throw it away!

Cool! The previous cooktop was a 10-12 yr old hybrid induction/radiant Jenn-Air, but its induction was wimpy-- one could not boil water using the induction! It was through the Appliance forum that I learned that model was known to be terrible.

I am so pleased that this new Bosch can boil water!

And I am so very grateful for these forums!