Proper Bonding. Don't damage your generator.

Why You Should Never Double Bond the Neutral on a Floating Neutral Generator in a Fixed Installation

March 2026  ·  4 min read

When connecting a generator to a fixed electrical system, few mistakes are as consequential — or as commonly misunderstood — as double bonding the neutral on a floating neutral generator. It's a wiring decision that can compromise safety, trip protection devices, and put you in violation of the National Electrical Code. Here's what every electrician needs to know.

What is a floating neutral?

A floating neutral generator is one where the neutral conductor is not bonded to the generator frame or earth ground at the unit itself. The neutral is intentionally left "floating" — meaning its reference to ground is established elsewhere in the system, typically at the main service panel or transfer switch.

Nearly all commercial-grade AC alternators manufactured today ship from the factory as floating neutral. This is the industry standard — so if you're working with a modern commercial generator, there's a very good chance you're already dealing with a floating neutral, whether it's labeled as such or not. Always verify before making any bonding decisions.

What is double bonding and why is it a problem?

Double bonding occurs when the neutral is bonded to ground at both the generator and again at the main panel or transfer switch. This creates two neutral-to-ground bond points in the same system — and that's where problems start.

With two bond points, current has a parallel path to flow back through the grounding system rather than solely through the neutral conductor. This can energize equipment enclosures, conduit, and other metal parts of the system — creating a shock hazard for anyone who contacts them.

Double bonding can also cause nuisance tripping of GFCIs, interfere with ground fault protection equipment, and create objectionable current on grounding conductors — all violations of NEC Article 250.

The right approach for fixed installations

The neutral-to-ground bond should exist in only one location — typically at the first means of disconnect or the transfer switch. If your transfer switch is a common neutral type, it will handle the bonding automatically. When in doubt, always consult the generator manufacturer's documentation and reference NEC Article 250.

One bond point, in the right place, is all a fixed system needs. Getting this right protects your crew, your equipment, and your code compliance — and it starts with understanding that floating neutral is now the default for virtually every commercial generator on the market.