Lightning damages corrugated stainless steel tubing, starts house fire

A lightning strike in a neighborhood in the interior region sparked a series of events which could have led to dire consequences.

Lightning struck the ground near a natural gas underground distribution line, energizing the tracer wire used by a gas utility to locate underground gas lines. This created an electrical arc that shorted from the tracer wire (serving the individual gas service to the home), to the gas service riser upstream of the gas meter.

This electrical arc caused a hole in a corrugated stainless steel tubing (CSST). The resulting gas leak and sources of ignition started a fire in the home. Fortunately, the fire occurred in an enclosed joist space that also carried a plastic water line. The water line melted and the water pressure doused the fire.

During the investigation, it was found that the home’s gas lines were not bonded as required by CSA B149-10 Natural gas and Propane installation and Handling Code (CSA B149-10) and the CSST manufacturer’s certified installation instructions.

The installation of CSST requires proper bonding, which means a low impedance path is obtained by permanently joining all non-current-carrying metal parts. This ensures electrical continuity and having the capacity to safely conduct any current likely to be imposed on it. Proper bonding and grounding will reduce the risk of damaged caused by a direct or indirect lightning strike.

Note: Bonding is electrical work and must comply with the Canadian Electrical Code part 1 and must be performed by a licensed electrical contractor.

CSA B149-10 section 4.7.3 indicates the requirements for interior metal piping to be bonded while section 4.1.3 further enforces the requirement for CSST to be installed according to the certified installation instructions.

This incident has resulted in continuing education to many gas fitters regarding the importance of ensuring that gas lines are properly bonded. Although this is a requirement that is usually looked after by a qualified electrician on a new construction, remember that the gas contractor is required by the gas code section 4.7.3 to ensure the bonding is installed. On retrofit work, there may not be a qualified electrician involved in a gas appliance installation.

It is important to note that proof of manufacturers’ training is required prior to installation of CSST. There are a number of different CSST brands. They all have detailed requirements for electrical bonding of their products in the manufacturers’ certified installation instructions.

If you have any questions, contact your local BCSA gas safety officer or call 1-866-566-7233 and we will have a gas safety officer get in touch with you.

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