Busway: flexible industrial distribution.
Busway (bus duct) is a metal-enclosed conductor system that distributes power along its length with plug-in tap capability. Industrial applications and large commercial buildings benefit from busway's flexibility.
By Steven Lockhart · Reviewed by Alex Towery, C-10 #989290
Updated 2026-06-16
Busway install scope: feeder busway (high-amperage, long distance) or plug-in busway (allows tap-in fusible/breaker units anywhere along length), section assembly, support and bracing, end feed and tap units, transition fittings to switchgear and panels. Marin commercial/industrial busway installations $80-$200 per linear foot for plug-in busway, $40-$120 per foot for feeder busway, plus tap units. Used primarily for installations 400A+ with distributed tap requirements.
01When busway makes sense.
Busway shines in distribution scenarios where multiple loads need to tap off a common high-amperage feeder at various points — warehouse and manufacturing floors with mobile or reconfigurable equipment, large retail stores with periodic tenant build-outs requiring power tap-ins at different locations, data centers and server rooms with distributed power needs. Conventional conduit/wire distribution would require pre-determined load locations; busway allows tap-ins anywhere along the busway length without re-pulling wire.
Cost comparison: traditional conduit/wire feeder + multiple sub-panels can be more economical for static load locations and lower amperages. Busway is more economical at high amperages (1,000A+) and where flexibility is valuable. Crossover point varies by project geometry, but typical break-even is 600-800A with 2-4 tap locations. We compare both approaches in design phase for projects in the gray zone.
02Busway types.
Feeder busway
Continuous run with no tap points. Used for transferring power from one location to another (service entrance to MDP, MDP to remote switchgear). Higher amperages, lower cost per foot than plug-in busway.
Plug-in busway
Has tap points every 24 or 30 inches allowing plug-in fusible or breaker units to be installed anywhere along the run. Flexibility comes with cost — 50-100% more per foot than feeder busway.
Amperage range
Residential-style busway doesn't really exist; busway starts at 100A and goes up to 5,000A+. Common Marin industrial installations 400-1,200A; larger data centers and industrial facilities use higher amperages.
03Install considerations.
Busway requires proper support and bracing per manufacturer specifications and NEC 368. Horizontal runs need support at typical 5-foot intervals; vertical runs need support per manufacturer. Seismic bracing required in California per CBC; bracing details depend on busway weight and orientation. Marin's seismic zone requires particular attention to bracing details — we follow manufacturer engineered designs and have AHJ pre-approval for typical installations.
Modular construction: busway comes in 10-foot standard sections plus shorter custom sections, elbows (vertical and horizontal), tees, end feed boxes, and tap units. Assembly is mechanical (bolted joints with engineered tightening specs) plus electrical connections at each joint. Field assembly typically 4-6 hours per 100 feet of straight run, longer for routes with fittings.
Common questions.
What's the lead time for busway?
4-8 weeks typical for residential-scale industrial busway installations (Square D, Eaton, GE are major suppliers). Larger or specialty installations 10-14 weeks. We design busway scope early in project to allow procurement lead time without delaying overall project timeline. Standard catalog busway has shortest lead time; custom configurations longer.
Can I add tap units after install?
Plug-in busway is designed for exactly this — install plug-in busway initially, add tap units (plug-in fusible or breaker units) as future loads need them. Adding tap units to existing plug-in busway is typically a 1-2 hour install per unit. Adding capacity (more amperage) requires upgrading busway sections, which is a larger project.
Is busway safe in seismic events?
Yes when properly braced per manufacturer requirements. Seismic bracing for California adds modest cost but is required by CBC for commercial installations. Properly braced busway has performed well in California earthquakes. Bracing details are engineered by manufacturer based on busway weight, length, and orientation; field installation follows engineered details.
What about busway maintenance?
Busway requires periodic inspection (visual annually, thermographic scan every 3-5 years), bolted joint torque verification (every 5 years per manufacturer), and tap unit testing as part of normal panel/breaker maintenance. Most Marin industrial installations include busway in their facility electrical preventive maintenance program. We provide maintenance services and contract pricing for ongoing operations.
How do you handle pricing — flat fee or hourly?
Both, depending on scope. Routine service calls and predictable scope (panel replacement, EV charger install, transfer switch install, fixture replacement) are flat-fee quoted up front. Diagnostic visits and emergency scope are hourly because we don't know what we'll find. Either way, you get a written quote before work starts on anything significant, and we don't proceed beyond the quote without your sign-off.
How quickly can you schedule?
Depends on scope and season. Emergency dispatch: same-day across Marin County (1-3 hours business hours, 1-4 hours after-hours). Same-day standard service: 3-6 hours from call when capacity allows; otherwise next business day. Scheduled service work: 1-3 weeks typical. Larger projects requiring permits and PG&E coordination: 4-12 weeks depending on scope. We're upfront about timeline at the quote stage.
What warranty do you offer on work?
Our standard residential warranty: 2 years on labor, manufacturer warranty on parts (varies by product — typically 1-10 years). Major installs (panels, generators, EV chargers) often have longer manufacturer warranties (5-10 years). If there's an issue with our work in the warranty period, we come back and fix it at no cost. We also stand behind work past warranty — repeat customers and referrals matter more than a transactional fix.
Are you licensed and insured?
Yes. California State License Board C-10 Electrical Contractor #989290, in good standing. Carry general liability insurance and workers' compensation insurance as required by California law. Bondable on projects requiring it. Happy to provide proof of insurance to clients or property managers on request. License lookup: cslb.ca.gov.
Talk to a licensed electrician in Marin.
Family-run, C-10 #989290, 20+ years in the trade. Honest scoping, fair pricing, work that lasts.