Duncan is one of the places where the usual Spartanburg County assumptions do not hold. Natural gas here comes from the Greer Commission of Public Works, not Piedmont. Permits for gas piping inside town limits come from the Town of Duncan's own building official, not the county. Get either one wrong and a simple job stalls.
The town has grown quickly, from about 3,200 people in 2010 to just over 4,000 in 2020, with industrial employers along I-85 and new subdivisions to house the people who work there. Most gas line work in Duncan now happens in those newer homes: tankless conversions, gas ranges, dryers and lines to the patio.
Homes around Main Street and the SC 290 and SC 292 crossroads are older and need a different eye. Their gas piping has often been extended piece by piece, and it deserves a leak check and a sizing review before anything new is added.
We are a short run down I-85 or US 29 from our base in Spartanburg. We plan the line, file with the town, run and test the pipe, and meet the inspector.
Greer CPW owns the meter, you own the rest
Greer CPW's gas system covers more than 400 square miles, reaching from Greer east past Duncan to Wellford. In Duncan, CPW owns the main, the service line and the meter. Every foot of pipe after the meter is private, and that is what we install.
If your plans add up to more gas than the existing meter is rated for, CPW decides whether to upgrade it, and that work runs on the utility's schedule. We add up the load early so a meter question does not surface the day the new appliance arrives.
Tankless is the big one
The most common gas line request in Duncan is a tankless water heater to replace the 40- or 50-gallon tank that came with the house. It is also the job most likely to need a bigger pipe. Many tankless units draw several times the gas of the tank they replace, and the builder's line was sized for the tank.
We size the new run from the meter outward, often as its own branch rather than a tee off the old water heater line. Venting changes too, since most tankless units vent through a wall in plastic or stainless pipe.
Slab homes and attic routes
Plenty of newer homes in and around Duncan are built on slabs, so there is no crawlspace to run pipe through. Gas lines in those houses typically travel through the attic in CSST and drop down inside a wall to the appliance.
That makes attic access and insulation part of the plan. It also makes bonding important, because CSST in an attic must be bonded to the electrical grounding as its manufacturer requires.
Patio grills, fire pits and outdoor kitchens
Newer homes with a back patio often get a natural gas line for a grill or fire pit. The run usually leaves the house in steel, goes underground in polyethylene pipe with a tracer wire, and comes back up through a steel riser with a shutoff near the appliance.
- Call SC811 before digging; it marks utility lines up to the Greer CPW meter
- Private lines past the meter are not marked, so keep a sketch of the route
- Check that the grill can be converted to natural gas, and buy the kit
- Plan the shutoff where you can reach it without leaning over the grill
Town permit, town inspector
Duncan permits its own construction work, and the building official works out of Town Hall on West Main Street. New gas piping inside town limits gets a town permit and a town inspection of the pressure test before it is covered or connected. For addresses outside town limits, the permit comes from Spartanburg County Building Codes.
In Duncan specifically
Not a Piedmont town
Neighbors who moved from Spartanburg sometimes call Piedmont about a Duncan meter. Duncan is in Greer CPW's gas territory, so meter and service questions go to CPW.
Builder-sized piping
Newer homes were piped for the appliances on the original plan. A second gas appliance, or a much bigger one, often needs a new branch rather than a tee into the old line.
Older homes near Main Street
Houses that predate the growth may have black steel through a crawlspace, extended over the years. We leak-test the existing system before tying anything new into it.
Propane outside the mains
Rural homes beyond the reach of Greer CPW's mains may run on propane. We pipe for propane pressure and make sure each appliance is set up for it.
How a gas line install runs
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Walk the job and add up the load
We look at the meter or tank, the existing piping and every appliance on it, and work out where the new line should tie in and what size it needs to be.
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Pull the permit
Gas piping is permitted work. We file with whichever building department covers your address, the City of Spartanburg or the county.
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Run the line
In the right material for each stretch, with a shutoff valve and a sediment trap at the appliance, supported and protected where it passes through framing.
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Pressure test
The new piping is capped and pressurized with air and held on a gauge. Under the fuel gas code the test is at least one and a half times the working pressure, never below 3 psi, for at least 10 minutes. Many inspectors ask for more. It has to hold with no drop.
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Inspection
The inspector sees the test on the gauge and checks the installation before anything is concealed or connected.
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Connect, purge, light and check
We connect the appliance, purge air from the line, light it, and check the flame and the connections for leaks. Every other appliance on the line gets relit and checked as well.
The full guide to gas line installation, and everything else about plumbing and gas in Duncan.