Generator Neutral Bonding: Home Interlock Safety & NEC 250.20 Explained
01 Floating Neutral vs Bonded Neutral Explained
Portable generators ship in one of two configurations: floating neutral or bonded neutral. In a floating neutral generator, the neutral conductor is isolated from the steel frame ground.
In a bonded neutral generator, the neutral wire connects to the generator frame. Units like the Honda EU7000iS and Champion 201176 come with factory floating neutrals.
- Floating neutrals isolate return currents from generator metal frame.
- Bonded neutrals tie neutral and equipment ground together internally.
- Residential breaker panels already have a main bonding jumper installed.
02 Why Home Interlocks Require a Floating Neutral
Your home service panel contains a utility neutral-to-ground bond. Connecting a bonded neutral generator to a manual transfer switch or interlock creates an illegal second ground bond.
This creates parallel return paths across ground wires. Current flows along water pipes and appliance chassis, presenting severe shock risks and tripping GFCI breakers instantly.
- 1 Inspect Generator Neutral Status: Check the data plate or use a multimeter between neutral and ground pin.
- 2 Verify Single Panel Bond: Ensure the utility breaker panel provides the single system ground bond.
- 3 Use Approved Interlock Kit: Install an approved mechanical interlock bracket on your panel.
03 How to Unbond a Generator for Home Interlock Use
If your generator has a bonded neutral, remove the neutral-to-ground bonding jumper wire behind the alternator end-cover. Store and label the jumper inside the panel cover for future jobsite use.
For safe installation by licensed residential electricians, explore certified professionals through our Atlanta Transfer Switch Electricians directory.