Rigid & IMC Compression Fittings Catalog | CT-27 Section 4
CT-27 Conduit Systems, Section 4. Threadless couplings and connectors for rigid metal conduit (RMC) and IMC, 1/2" through 2", UL 514B. This page mirrors the printed catalog section. Shop the collection or request submittal data from the trade desk at 1 (307) 206-0534.
Download the catalog section (PDF, 5 pages) Print-ready. Use it as a submittal sheet or trade desk handout.
Overview
Compression fittings join and terminate unthreaded rigid and IMC with a wrench: cut square, ream, insert to the stop, tighten. No threader, no cutting oil, no rotating the pipe. Zinc plated steel body, split compression ring and hex nut. Listed to UL 514B and permitted by NEC 344.42(B) and 342.42(B) where listed for the purpose.
| Feature | What it means on the job |
|---|---|
| Threadless install | Field cuts, tie-ins and repairs finish in minutes with two wrenches |
| Sized to RMC/IMC OD | Rigid and IMC share OD by trade size, so one fitting covers both. Not for EMT |
| UL 514B listed | Conduit fitting listing accepted by AHJs nationwide; NEC 344.42(B) / 342.42(B) |
| Concrete tight (RT connectors) | Pour in place at slab stub-ups and equipment pads |
| Zinc plated steel | Corrosion resistance for indoor and protected outdoor locations |
| Cross referenced | Drops into RACO and Bridgeport specs and submittals |
RTC series couplings join two lengths of unthreaded conduit end to end. RT series connectors terminate conduit into a box, panel or enclosure through a knockout, secured with a locknut.
Why threadless
- Labor. The installed joint is what costs money. Threading a cut end needs a vise, threader, dies, oil and a reamer, and several minutes per end. A compression joint is cut, ream, slide, tighten.
- Access. Existing runs are strapped, concealed and landed at both ends; they do not rotate into a threaded coupling. A compression coupling joins to them in place.
- Fewer tools and trips. No threader rental, no dies, no cutting oil in a finished space. A short cut is a coupling and a stub, not a new stick.
- Grounding continuity. The compression ring bites clean metal under wrench torque, keeping the raceway as a continuous equipment grounding path.
Full article: Why Use Threadless Rigid Compression Fittings.
Where to use
| Application | Typical fitting | Notes |
|---|---|---|
| Tie-ins to existing rigid runs | RTC coupling at the cut, RT connector at the enclosure | The most common use. Existing pipe cannot rotate into a threaded coupling |
| Field cut lengths | RTC coupling or RT connector | Every run ends in a cut stick. Finish it without a threader |
| Repairs and damaged sections | Two RTC couplings + new conduit | Vehicle strikes, corrosion at grade, demo damage |
| Short nipples and tight spaces | RT connector each end | Between disconnect and starter, through walls, mechanical rooms |
| Concrete encased / slab stub-ups | RT connector at the enclosure | Connectors listed concrete tight; pour in place |
| Retrofit and tenant improvement | RTC coupling, RT connector | Extend or reroute concealed existing rigid |
| Solar, EV, equipment pads | RTC at the riser transition, RT at the enclosure | Field cuts at grade and at inverters, EVSE, transformer pads |
Specify by location
| Location | Fitting | Listing to confirm |
|---|---|---|
| Indoor dry, exposed or above ceiling | RTC coupling, RT connector | UL 514B |
| Concrete encased, slab stub-ups | RT connector at enclosure | UL 514B, concrete tight |
| Outdoor / wet location | Raintight listed fitting or threaded | UL 514B, raintight |
| Hazardous (classified), NEC 500 series | Threaded only | No threadless fittings permitted |
| Direct burial, corrosive environment | Fitting listed for the environment | Per listing |
Full article: Where to Use Rigid Compression Fittings.
Buyer's guide: sizing
Rigid and IMC share these outside diameters. Match the fitting to the trade size stamped on the conduit. These fittings will not seal on EMT.
| Trade size | RMC / IMC OD | CT coupling | CT connector |
|---|---|---|---|
| 1/2" | 0.840 in | RTC-50 | RT-50 |
| 3/4" | 1.050 in | RTC-75 | RT-75 |
| 1" | 1.315 in | RTC-100 | RT-100 |
| 1-1/4" | 1.660 in | RTC-125 | RT-125 |
| 1-1/2" | 1.900 in | RTC-150 | RT-150 |
| 2" | 2.375 in | RTC-200 | RT-200 |
Cross reference
Couplings and connectors are separate part families at both manufacturers. Bridgeport offers a standard malleable iron version and an RT (raintight) steel version. Crosses identify the same trade size, raceway and fitting type; ratings differ by series, so confirm on the manufacturer datasheet before substituting on a specified job.
Couplings
| Trade size | CT | RACO | Bridgeport | Bridgeport raintight |
|---|---|---|---|---|
| 1/2" | RTC-50 | 1822 | 3100 | 3100-RT |
| 3/4" | RTC-75 | 1823 | 3101 | 3101-RT |
| 1" | RTC-100 | 1824 | 3102 | 3102-RT |
| 1-1/4" | RTC-125 | 1825 | 3103 | 3103-RT |
| 1-1/2" | RTC-150 | 1826 | 3104 | 3104-RT |
| 2" | RTC-200 | 1828 | 3105 | 3105-RT |
Connectors
| Trade size | CT | RACO | Bridgeport | Bridgeport raintight |
|---|---|---|---|---|
| 1/2" | RT-50 | 1802 | 3000 | 3000-RT |
| 3/4" | RT-75 | 1803 | 3001 | 3001-RT |
| 1" | RT-100 | 1804 | 3002 | 3002-RT |
| 1-1/4" | RT-125 | 1805 | 3003 | 3003-RT |
| 1-1/2" | RT-150 | 1806 | 3004 | 3004-RT |
| 2" | RT-200 | 1808 | 3005 | 3005-RT |
RACO series listed concrete tight (dry locations); Bridgeport plain numbers are malleable concrete tight, -RT are steel raintight. RACO numbers verified on Hubbell specification sheets; Bridgeport 3100-RT series, 3002-RT and 3005-RT verified on distributor listings, remaining 3000 series by sequence.
Ratings and construction
| Item | CT RTC / RT series |
|---|---|
| Standard | UL 514B, conduit fittings |
| Code basis | NEC 344.42(B) rigid, 342.42(B) IMC, threadless fittings listed for the purpose |
| Concrete tight | RT series connectors |
| Temperature | 90°C (RT series) |
| Material / finish | Steel body, ring and nut, zinc plated |
| Raceway | Unthreaded RMC and IMC only |
Installation
- Cut the conduit square. Ream the inside edge so the ring seats evenly and conductors are not damaged.
- Slide the nut and ring onto the conduit. Push the conduit fully into the body until it bottoms on the stop.
- Hand tighten, then wrench tight. Do not use a pipe wrench on the body.
- Connectors: install the locknut inside the enclosure wrench tight, then the bushing.
- Where the raceway is the equipment grounding conductor, verify continuity. Clean painted or corroded pipe back to bright metal at the cut.
Companion line: EMT compression couplings (3105 series)
For EMT runs, the 3105 series compression coupling is the companion product, sized to EMT OD. Do not interchange with rigid fittings.
| Trade size | EMT OD | CT part | RACO | RACO raintight | Bridgeport | Bridgeport raintight |
|---|---|---|---|---|---|---|
| 1/2" | 0.706 in | 3105-0012 | 2922 | 2922RT | 260 | 260-RT / 260-SRT |
| 3/4" | 0.922 in | 3105-0034 | 2923 | 2923RT | 261 | 261-RT / 261-SRT |
| 1" | 1.163 in | 3105-0001 | 2924 | 2924RT | 262 | 262-RT / 262-SRT |
| 1-1/4" | 1.510 in | 3105-0114 | 2925 | 2925RT | 263 | 263-RT / 263-SRT |
| 1-1/2" | 1.740 in | 3105-0112 | 2926 | 2926RT | 264 | 264-RT / 264-SRT |
| 2" | 2.197 in | 3105-0002 | 2928 | 2928RT | 265 | 265-RT / 265-SRT |
Quick selector
| You have | Use |
|---|---|
| Unthreaded rigid or IMC, joining two lengths | RTC series rigid compression coupling |
| Unthreaded rigid or IMC, into a box or panel | RT series rigid compression connector |
| EMT, joining two lengths, dry location | 3105 series EMT compression coupling |
| EMT, into a box, dry location | 3101 series EMT compression connector |
| Any of the above outdoors | Raintight listed fitting (ask the trade desk) |
| Hazardous (classified) location | Threaded rigid system only |
Ordering
Order by CT part number from the collection. Sold each; box and case quantities and project pricing through the trade desk, 1 (307) 206-0534, or the distributor and contractor program. Same-day shipping on in-stock items.
Download this section as a PDF
Related: Buyer's Guide · Where to Use · Why Threadless · Cross-reference hub
