The service pipe by which the gas is conveyed to a building is always put in by the gas company. The size of this pipe is governed by the number of burners to be supplied, but it should never in any case, even for the smallest house, be less than 1 inch in diameter. This may be slightly larger than is necessary, but the cost is only a little more and the liability of stoppages is much less; this also allows for the future addition of more burners, which is often a matter of much convenience. Service and distributing pipes for water, or naphtha gas, should be from 15 to 20 per cent larger than for coal gas. The material for the main service pipe, from the street to the house, should be either lead or wrought iron. As a rule, wrought-iron pipe with screwed joints is preferable to lead, because it is less likely to sag in the trench, thus causing dips for the accumulation of water of condensation. Care must be observed in the use of wrought-iron pipe to protect it by coating with asphalt, or coal tar, to prevent corrosion. The pipe should also be well supported in the trench. Service pipes should preferably rise from the street gas main toward the house in order to allow all condensation to run back into the mains. This, however, cannot always be done, owing to the relative levels of the street main and the meter in the house. The latter should be placed in a cool, well-lighted position, at or below the level of the lowest burner, which is usually in the cellar. If the meter is below the gas main, the service pipe must grade toward the house and should be provided with a drip pipe, or "siphon," before connecting with the meter.

When water accumulates in the siphon, the cap is removed and the pipe drained. The gas company usually supplies and sets the meter, which should be of ample size for the number of lights burned.

A stopcock, or valve, is placed by the company in the service pipe, so that the gas may be shut off from each building separately. This is usually placed outside near the curb in the case of buildings requiring a pipe 1 1/2 inches in diameter, or larger. In the case of theaters or assembly halls it is often required by law as a safeguard in case of fire. The meter is connected with both the service pipe and the main house pipe by means of short connections of extra heavy lead pipe. A cock is placed near the meter, and in large buildings this is arranged so that a lock may be attached to it when the gas is shut off by the company. Gate valves are preferable for gas mains, as they give a free opening equal to the full size of the pipe.