T225 Busway Grounding, Isolated Ground & 200% Neutral
Compare housing ground, Isolated Ground (IG), 200% Neutral (N2) and N2IG for the T225 / 225A Track Busway system. See inside all four configurations, understand dedicated ground versus isolated ground, and choose matching feeds, busway lengths, electrical joiners and tap-offs.
Match the path through every component
- Power feed: connects the specified supply and grounding arrangement.
- Busway length: carries the selected conductor configuration.
- Tap-off: maintains the required connection to the receptacle or equipment.
See inside the four T225 configurations
Each view shows the same T225 assembly with its feed cover and busway side removed. The color accents below identify the configuration; they do not represent field-wire colors.
Standard uses the bonded housing and standard neutral. Isolated Ground (IG) adds the separate middle grounding conductor. 200% Neutral (N2) adds lower neutral copper for 200% neutral capacity. N2IG combines Isolated Ground and 200% Neutral.
The aluminum housing and metal enclosures remain grounded in every configuration.
Compare T225 Grounding & Neutral Options
| Configuration | Neutral capacity | Isolated Ground | Housing ground |
|---|---|---|---|
| StandardStandard neutral | Standard | No | Maintained |
| IGIsolated Ground | Standard | Yes | Maintained |
| N2200% Neutral | 200% | No | Maintained |
| N2IGIsolated Ground + 200% Neutral | 200% | Yes | Maintained |
Housing ground is maintained in every configuration. The aluminum busway housing and metal feed and tap-off enclosures remain grounded. Isolated Ground (IG) adds a separate insulated grounding path; it does not replace housing ground.
200% Neutral (N2): What Changes
Why specify 200% neutral?
Some nonlinear loads produce harmonic currents that add together in the neutral of a three-phase system instead of canceling. The resulting neutral load can call for additional neutral capacity.
200% Neutral (N2) provides that additional capacity when specified by the project load calculations. It does not filter harmonics or increase the T225 system’s 225A phase rating.
Neutral capacity and grounding serve different purposes
Neutral carries load current. Equipment grounding and bonding provide the protective grounding path. N2 maintains the housing ground and does not add Isolated Ground by itself.
N2IG combines 200% Neutral with a separate Isolated Ground path. Coordinate neutral capacity through the supply conductors, feed, busway and electrical joiners.
Does every electronic load need a 200% neutral?
No. Select neutral capacity from the actual connected loads, anticipated harmonic currents and project electrical design. Electronic equipment varies; the presence of computers or other electronic loads alone does not establish an N2 requirement.
Isolated Ground (IG): Details That Matter
The housing remains grounded with IG
Isolated Ground (IG) describes the separate insulated path to the compatible isolated-ground receptacle or equipment. It does not mean the metal busway housing or feed and tap-off enclosures are left ungrounded.
Preserve that separate path through the specified feed, busway, tap-off and field wiring to the designated grounding point.
An isolated-ground receptacle needs a compatible assembly
A compatible isolated-ground receptacle must be supported by the complete Isolated Ground (IG) configuration. USA TrackBusway supplies receptacles in compatible factory-assembled tap-offs.
Dedicated Ground (DG) vs. Isolated Ground (IG)
Dedicated Ground (DG) adds an internal grounding conductor bonded to the equipment-grounding path and housing in the specified assembly. Isolated Ground (IG) uses a separate insulated grounding conductor, kept separate from the housing along the distribution path to the designated grounding point. The housing remains grounded in both arrangements.
That difference must continue through compatible components. A DG component that bonds the extra grounding conductor to its housing can defeat isolation when placed in an IG path. Select the complete configuration from the approved drawings; do not treat DG and IG components as interchangeable.
For T225, DG is a project-specific requirement rather than one of the four configurations compared above. Confirm a dedicated-ground specification with USA TrackBusway →
Does Isolated Ground eliminate electrical noise?
IG can help address noise coupled through shared grounding paths, but it does not guarantee noise-free power or correct every power-quality issue. Its effectiveness depends on the complete grounding arrangement, connected equipment and installation.
Can an isolated-ground receptacle alone create an IG system?
No. The receptacle’s isolated grounding contact needs a compatible path through the tap-off, busway, electrical joiners, feed and field wiring. The metal housing and enclosures retain their separate equipment-grounding path. Choose matching T225 components below.
Choose the matching T225 components
Match the conductor configuration through the lengths, power feed and electrical joiners. Then select the PowerDrop or outlet-box tap-off for the equipment’s voltage, current, neutral and grounding requirements.
T225 PowerDrop cords
T225 outlet boxes
40A Track Busway: housing ground
The 40A system always uses housing ground for equipment grounding. Isolated ground (IG) and 200% neutral are not options on the 40A system. The T225 conductor configurations illustrated above apply to T225 / 225A busway.
40A tap-offs are rated up to 40A, with the selected breaker, receptacle and assembly determining the usable branch rating. Compare 40A receptacle and tap-off selection requirements →
Plan the complete configuration
- T225 system and supply: supply voltage, phase, load and run arrangement.
- Grounding and neutral: Standard, IG, N2, N2IG or a project-specific DG requirement.
- Equipment connection: receptacle designation, current, neutral requirement and tap-off selection.
- Project documents: one-line diagram, load calculations and grounding details for review by the project electrical engineer.
