Induction Cooktop, no neutral (?!)
I'm in Minnesota, hoping for some advice on wiring my induction cooktop. This is crazy to figure out: no neutral lead from the appliance! The specs are:
The install manual says:
"Frame grounded by connection of grounding lead to neutral lead. If used in a mobile home of if local codes do not permit grounding through neutral, open connection and use grounding lead to ground unit in accordance with local codes. Connect neutral lead to branch-circuit neutral conductor in usual manner.
Attach flexible conduit to the junction box.
CAUTION: To reduce the risk of electric shock and fire, do not use a flexible power-supply cord.
Connect the cooktop lead wires to the junction box supply wires in proper phase:
black (L1) to black
red (L2) to red
green wire to ground
If the cooktop is installed and connected as specified above, it will be completely grounded in compliance with the National Electrical Code. "
Here is my proposed wiring, 6 gauge.
I would use the big blue wire nuts, for 6 gauge.
If this is indeed a case where, as they note "local codes do not permit grounding through neutral", they suggest to "open connection and use grounding lead to ground unit in accordance with local codes. Connect
neutral lead to branch-circuit neutral conductor in usual manner."
What the heck does "open connection" mean?
Some online forums seem to suggest that the wiring I propose would be
fine for a pure 3-wire 240V situation, but not for a 240V/120V
situation, where there are blower motors and other things in the
appliance. In that case, the forums suggest, a neutral must be
provided. I don't know how to make one up, if the circuit inside the
appliance has already mingled neutral and ground.
I have a 50amp breaker ready to go
What is the right way to get this done?
Thanks to everyone for this great forum.
How many leads (conductors) are hanging out of the flex? What size are they? What is the rated kW of your cooktop? You may not need such a large circuit. Can you take a close-up picture of the nameplate and the end of the flex?
Some manuals give generic instructions for different units. IF your unit does not even have a neutral wire in it, then that section would not apply. Look carefully at the leads coming out of the flex. Are any of them crimped together?
Meaning, to disconnect the neutral wires from the ground wires, or to disconnect neutral wires from the chassis, and provide another conductor (green or white) as needed through the (flexible) conduit to the junction box.
Looks like you edited your post to add the pictures in after my initial reply. They do clear up a couple of issues.
From what I see here, your supply circuit is a bit oversized: The nameplate rating is 7.2 kW which = 30 Amps. A #10 wire and a 30 Amp breaker would have been sufficient.
Since you oversized your circuit conductors, you'll have to stick with that 50 Amp breaker, or else your equipment grounding conductor is too small to comply with the Code.
No neutral wire is needed for this appliance.
How would it violate code by decreasing the breaker size to the correct breaker size? Would think at having a larger breaker size the appliance is not being protected like it should. Even though the wire size is larger than needed, no big deal.
The breaker is not there to protect the appliance, it is there to protect the wires from overheating. You can use a 50A breaker with #6 wire, or you could install a 40A or 30A breaker. The appliance is almost certainly protected by an internal fuse, in any case appliance protection is the responsibility of the manufacturer.
IT violates the code because you have essentially upsized the circuit conductors without a corresponding upsizing of the equipment grounding conductor.
The section of the Code you need to refer to here is 250.122(B):
Of course, your inspector-critter may not be bothered with it either way .... :whistling2:
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