Conduit Fittings 101 for Long Island Contractors: Safe, Code-Ready Installs

Updated: October 13, 2025

~11 min read • ~2,200 words • Flesch ~60

TL;DR: Pick listed fittings that match the raceway and environment, confirm bonding and any insulated bushing needs, use the right sealing hardware in wet or corrosive spots, and document everything for the AHJ. Follow NEC 2023 Articles 300, 250, and the raceway-specific Articles for coupling and connector rules. When uncertain, ask the local inspector first.

Why it matters

Conduit fittings do the quiet work that keeps jobs safe, compliant, and billable. They protect conductors at sharp transitions, bond metal systems, keep water out, and maintain the continuity inspectors look for. When fittings fail, you get nuisance trips, corrosion, damaged insulation, and callbacks. When they are chosen and installed right, you move faster, pass inspections, and reduce rework.

Start with the basics: pick fittings that are listed for your raceway, location, and environment. Then verify bonding, enclosure ratings, and any insulated throat or bushing requirements before you pull wire. For material choices, match the job: steel or malleable iron for durability, PVC conduit fittings for wet or corrosive areas, and liquidtight fittings where flex meets weather. If you need help sourcing, check Revco’s EMT fittings and liquidtight connectors selections early in design.

Local note: On Long Island, individual towns, villages, and counties may amend or phase in code adoptions on their own timelines. Always confirm requirements with the local Authority Having Jurisdiction (AHJ) before you buy or install.

Fundamentals

What conduit fittings actually do

• Protect conductors at entries and bends with bushings and insulated throats.
• Maintain raceway continuity with couplings and connectors so equipment grounding paths stay effective.
• Seal against dust and moisture with listed gaskets, o-rings, and sealing washers where required.
• Transition between sizes or materials using adapters specifically listed for that purpose.
• Mount and align raceways with straps and clamp backs to preserve clearances and spacing.

Common fitting families you will use most

• Bushings and insulated fittings: protect conductors at raceway ends and meet insulated fitting thresholds when required.
• Couplings and connectors: join raceways and boxes while keeping mechanical strength and electrical continuity.
• Adapters and reducers: handle transitions in trade size or material. Use only listed combinations.
• Elbows and bends: factory elbows save time and preserve conductor space when site bends are not practical.
• Clamp backs and straps: maintain alignment and stand off where surfaces are uneven or where drainage or cleaning is needed.
• Liquidtight and corrosion resistant options: for washdowns, rooftops, marinas, and parking structures, consider RMC and IMC fittings or liquidtight families with the right environmental rating.

Code & compliance (NEC 2023 references)

Use these as planning checkpoints. Always verify local adoption and amendments with the AHJ.

• Raceway continuity: Raceways must be continuous and mechanically secured. See NEC 300.10 for continuity. Couplings and connectors for each raceway type are addressed in the raceway Articles, such as 358.42 for EMT, 344.42 for RMC, and 342.42 for IMC.
• Where insulated fittings are required: NEC 300.4(G) covers insulated fittings to protect conductors where they emerge from raceways in specific conditions. Also consider 300.15 for fittings at junctions and entries.
• Bonding of fittings: Metal raceways and associated fittings must be bonded so fault current clears effectively. See NEC 250.96 and 250.97 for bonding requirements, including around nonmetallic raceway breaks and around concentric or eccentric knockouts when applicable.
• Corrosion protection and wet locations: NEC 300.6 covers corrosion protection for ferrous parts. Underground and wet location practices appear in 300.5 and in the raceway Articles for selections like PVC (352), LFMC (350), and LFNC (356).
• Raceway specific selection:
  • EMT: Article 358, including 358.42 for couplings and connectors and 358.60 for grounding and bonding.
  • RMC: Article 344, including 344.42 for couplings and connectors.
  • IMC: Article 342, including 342.42 for couplings and connectors.
  • PVC (RNC): Article 352 for locations, support, and temperature considerations.
  • LFMC and LFNC: Articles 350 and 356 for fittings, equipment grounding considerations, and wet location rules.
• Boxes and fittings: NEC 300.15 addresses where fittings are required and how raceways terminate into boxes and enclosures.

Beyond the NEC, confirm the fitting carries a listing mark appropriate to its category, such as UL 514B for conduit, tubing, and cable fittings, and check any NEMA FB 1 guidance for ratings and construction features.

Selection steps

1. Identify the raceway type and location. EMT, RMC, IMC, PVC, LFMC, or LFNC, and whether the area is dry, damp, wet, corrosive, or subject to sunlight and temperature swings. This drives material and gasket choices. If you expect washdown or coastal exposure common on Long Island, lean toward corrosion resistant fittings and consider weatherproof boxes and covers.
2. Match the listing. Choose a fitting listed and labeled for that raceway and environment. Avoid mixing plumbing parts or unlisted reducers. For transitions, use adapters specifically listed to join the two systems.
3. Confirm bonding and insulated needs. Where metal raceways terminate or pass through concentric or eccentric knockouts, evaluate bonding bushings or bonding jumpers as required by NEC 250.96 and 250.97. Where insulated fittings are called for by NEC 300.4(G), select bushings or connectors with insulated throats.
4. Check enclosure and sealing ratings. For wet or outdoor locations, use fittings with appropriate ingress protection and any required sealing washers or o-rings. In hazardous or classified spaces, follow the specific Article and manufacturer instructions for sealing fittings.
5. Plan support and alignment. Use straps and clamp backs to maintain stand off and straight runs. Proper alignment protects conductor insulation, makes pulls easier, and looks professional at inspection.
6. Document and verify. Note fitting part numbers and listing categories on your submittals. Photograph terminations that use bonding bushings or specialty adapters so the inspector can see details without removing conductors.

Sizing and configuration choices

No math here. Use listed fittings that match trade size and raceway type. Maintain box fill and conductor bending space by using factory elbows where tight routing would crowd the enclosure. For reducers or adapters, rely on products listed for the exact transition and avoid makeshift stacks that defeat listing or bonding. If a knockout pattern creates concentric rings, plan for bonding provisions.

Installation and wiring notes

• Thread engagement: For threaded systems like RMC and IMC, ensure full thread engagement per manufacturer guidance so the fitting can bond and seal correctly.
• Torque: Many listed connectors specify a tightening range. Follow the instruction sheet to avoid loose terminations or cracked hubs.
• Sealants: Use thread sealants only where the manufacturer permits them. On plastic threads, avoid products that attack PVC. For wet locations, use the sealing washers supplied with the fitting.
• Orientation and drainage: On outdoor boxes, position fittings and hubs to shed water. Use conduit bodies with covers and gaskets where accessible pulls are needed.
• Support and stand off: Maintain support spacing per the raceway Article. Clamp backs help keep straight lines and allow washdown behind the run.
• Mixed materials: When transitioning from metal to nonmetallic raceways, confirm bonding continuity around the break, often with bonding bushings or jumpers.

Testing, commissioning, and documentation

• Continuity check: Verify the equipment grounding path using a low resistance measurement or accepted continuity test before energizing.
• Bonding verification: Inspect for bonding bushings, locknuts, or jumpers where concentric or eccentric knockouts are present.
• Ingress control: Perform a visual wet check where appropriate to confirm gaskets and sealing washers are seated.
• Photos and notes: Capture labeled photos of unusual adapters, sealing fittings, or bonding arrangements for the closeout package and AHJ record.
• Spare parts log: Record which fittings were consumed and which failed during install so purchasing can adjust stocking levels.

Troubleshooting

• Frequent AFCI or GFCI trips: Check for loose connectors that compromise equipment grounding continuity.
• Water in boxes: Inspect for missing or incorrect sealing washers, cracked hubs, or fittings not listed for wet locations.
• Damaged insulation at entries: Add or replace insulated bushings and verify bushing size matches the raceway.
• Galvanic corrosion: Avoid dissimilar metals in coastal sites. Choose stainless or nonmetallic fittings where appropriate.
• Stripped threads or spinning locknuts: Replace the fitting and reassess torque practices and knockout condition.

Common mistakes

• Using unlisted reducers or plumbing parts to make a size change.
• Skipping bonding bushings at concentric or eccentric knockouts when required.
• Relying on paint for corrosion protection without meeting code intent or manufacturer guidance.
• Overtightening set screws or compression nuts until threads deform.
• Ignoring UV resistance on nonmetallic fittings used outdoors.

Parts to stock

• EMT compression connectors and couplings in common trade sizes.
• Bonding and insulated bushings sized for your typical feeders.
• RMC and IMC threaded hubs, locknuts, and sealing washers.
• Liquidtight straight and 90 degree connectors with gaskets.
• PVC adapters, male terminal adapters, and expansion fittings for exterior runs.
• Conduit connectors plus assorted pulling lubricants and accessories to speed the pull.

Shop at Revco: Browse EMT fittings, PVC fittings, and liquidtight fittings or call (631) 283-3600 for help matching listings and environments.

When to call the AHJ or an engineer

• Anytime local amendments could change a national rule or when code adoption dates are unclear.
• When using unusual adapters, sealing fittings, or when combining materials that raise bonding questions.
• In corrosive, hazardous, or high fault current environments where details matter.

Safety disclaimer

This guide is for qualified electrical professionals. Follow OSHA safe work practices, manufacturer instructions, and NEC 2023. Long Island jurisdictions may amend or phase in code differently. Confirm requirements with the AHJ before installation or inspection.

FAQ

• Do I need insulated bushings on every metal raceway? No. Use them where NEC 300.4(G) or the equipment listing requires added protection at conductor exits or entries.
• How do I prove bonding at concentric knockouts? Use listed bonding bushings or jumpers where required by NEC 250.96 and 250.97, and keep documentation or photos for the AHJ.
• Can I mix metal and PVC in the same run? Yes, with listed transitions and maintained bonding continuity around nonmetallic sections.
• Are liquidtight connectors required outdoors? Only where the location is wet or subject to moisture. Use fittings listed and gasketed for that environment.

Author: Revco Editorial Team — Electrical Content Editor

Technical review: Pending — add approved name and credential

Contact: (631) 283-3600

About Revco Lighting & Electrical Supply

Since 1978, Revco Lighting & Electrical Supply has been helping professionals bring their projects to light—literally. As a go-to source for lighting and electrical products across Long Island, NY and nearby areas, we specialize in supporting contractors, builders, and industry experts with practical solutions and dependable service. Whether it’s a complex commercial build or a simple residential upgrade, we’re here to make sure you have what you need, when you need it.

Sources

1. NFPA. “NFPA 70, National Electrical Code, 2023 Edition” — Articles 250, 300, 342, 344, 350, 352, 356, 358. Retrieved 10 2025. nfpa.org/NEC
2. UL Standards. “UL 514B: Conduit, Tubing, and Cable Fittings.” Retrieved 10 2025. ulstandards.ul.com/standard/?id=514B_11
3. NEMA. “FB 1 Fittings Standard.” Retrieved 10 2025. nema.org/standards/view/fb-1-fittings
4. IAEI Magazine. “Bonding for Services: Dealing with Concentric and Eccentric Knockouts.” Retrieved 10 2025. iaeimagazine.org
5. EC&M. “Bonding Bushings and Knockouts: What Inspectors Look For.” Retrieved 10 2025. ecmweb.com
6. Bridgeport Fittings, RACO, Carlon. Manufacturer installation sheets for fittings torque, sealing washers, and usage. Retrieved 10 2025. bridgeportfittings.com; raco.com; carlon.com