Adding a Gas Range to an Existing 1/2-Inch Gas Main in Dover
A 1,200-square-foot ranch in Dover has a 1/2-inch black iron gas line from the meter to a basement manifold. The run is 35 feet from the meter to the farthest existing appliance. The existing load is an 80,000 Btu/h furnace and a 40,000 Btu/h water heater. The homeowner is adding a 60,000 Btu/h range in the kitchen, 25 feet of branch from the manifold. The gas is natural gas at 7 inches water column. The contractor proposes to keep the 1/2-inch main and use a 1/2-inch CSST connector to the range. The range shutoff will be in the basement, 8 feet from the appliance, and the connector will pass through a floor joist bay to the kitchen. The local gas inspector has flagged the plan for sizing, sediment trap, and bonding.
1. Size the gas main and the range branch using the longest-length method.
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The total connected load is 80,000 + 40,000 + 60,000 = 180,000 Btu/h. The longest length from the meter to the farthest appliance is 35 feet to the manifold plus 25 feet of branch = 60 feet. Using the capacity table for natural gas at the available pressure, 1/2-inch black iron at 60 feet can carry roughly 50,000 Btu/h, far less than 180,000. Even 3/4-inch at 60 feet is only about 109,000 Btu/h, which is still undersized. A 1-inch main is required, or the load must be reduced. The range branch itself is 25 feet and carries 60,000 Btu/h; 1/2-inch at 25 feet can carry roughly 85,000 Btu/h, so the branch size is acceptable if the main is upgraded. The inspector should require a sizing calculation using the actual longest length, not just the 35-foot main run.
2. Evaluate the proposed shutoff location and CSST connector routing.
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The shutoff is in the basement, 8 feet from the range. The code generally requires the appliance shutoff to be in the same room as the appliance and within 6 feet of the appliance, unless the appliance is in a location where a remote shutoff is specifically permitted. A basement shutoff 8 feet away and separated by a floor is not acceptable as the appliance shutoff. The connector must be listed for the appliance, not concealed in a floor or ceiling, and must not pass through a floor joist bay in a way that makes it concealed or subject to damage. The connector length is also limited; many listed connectors are limited to 6 feet. The installer should run rigid pipe or a listed CSST system to the appliance location and provide an accessible shutoff within 6 feet in the same room, plus a sediment trap with a 3-inch drip leg at the range.
3. What bonding and sediment-trap requirements apply to the CSST installation?
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CSST must be bonded in accordance with the manufacturer’s instructions and the fuel gas code, typically by connecting the CSST system to the grounding electrode system with a listed bonding clamp and conductor sized for the service. The bond is intended to equalize potential and reduce the risk of arc damage, not to replace the equipment grounding conductor. A sediment trap is required at the range and at each appliance unless the appliance is specifically exempt; it should be installed downstream of the shutoff and as close as practicable to the appliance, with a drip leg at least 3 inches long. The inspector should verify that the CSST is listed, that it is not concealed in a way that violates its listing, that the bonding connection is accessible, and that the range connector is not used to make the final connection through a wall or floor.