Neutral and ground in a subpanel

What to try

1. 1On Wired right, set Heater to 1,500 W. All the current comes back on the feeder neutral, and the ground wire carries none.
2. 2Pick Bonding screw left in. Part of the current now comes back on the ground wire and the metal can whenever the heater runs.
3. 3Pick Screw in, neutral loose. All the current comes back on the ground wire, and the heater still runs, so nobody notices.

NEC 2026 sections it covers

250.24(C)

At the service, the main bonding jumper ties the neutral to the ground bar and the can.

250.24(B)

The neutral is not bonded again past the service.

250.142(B)

Past the service, the neutral must not connect to ground wires or metal parts.

408.40

A panel's ground bar is bonded to its metal can.

250.28(B)

A bonding screw used as the main bonding jumper is green.

250.6(A)

Grounding must not put normal current on ground wires.

250.30

A transformer follows its own bonding rules.

250.32

A separate building follows its own rules too.

334.80(A)

NM cable carries its 60°C amps.

Table 310.16

The table of allowed amps for each wire size.

Table 250.122

It sizes the feeder's ground wire from its breaker.

240.4(D)

12 AWG copper gets a 20 A breaker at most.

210.8(A)

A basement receptacle in a home needs GFCI protection.

Section numbers only. Read the full text in your code book. Temperatures and times in the visual are teaching models.

See something wrong? Tell us and we will check it against the code.