Stray electrical current is a very definite problem and procedures as detailed in O H & S documents have detailed this over a long period.

These types of incidents are real and not just the figment of someone’s imagination and some that come to mind are described below.

The method of overcoming stray electrical currents and gas piping is covered in Australian Standard 5601-2004 (2.11.4) that promotes the use of a metallic bridging device commonly known as a Bonding Strap.

AS 3500.1-2003 also describes the use of Bonding Straps and that they should have an electrical current rating of not less than 70 Amps.

Yesteryear the Gas & Fuel Corporation issued every individual person who was involved with fitting or disconnecting of Gas Meters, pipework and appliances with a set of Bonding Straps or equipment with similar abilities to suit different applications i.e.

Cable that had specifically designed ‘G’ clamps to suit large installations or pipe work.

The most commonly known use for using Bonding Straps is when cutting pipework.

Always place one clamp on either side of cut that is to be performed and always work with the Bonding Strap in place even if either side of the cut pipe test safe with a Neon tester or Multi Meter.

Electrical appliances such as Refrigerators, Washing Machines and Dishwasher cycle during their operation therefore voltage (and any fault with these appliances) may not be detected when testing either side of the cut pipe during a dormant period
between cycles.

Bonding Straps should also be used when disconnecting
• an appliance and/or replacing an appliance
• water and gas pipes
• changing a gas control

Incidents investigated have found the house where work may be carried out has no inherent fault with the electrical installation but the fault was traced to the electrical distribution system, (the) residence next door or up the Street and the fault in that residence has travelled through the mains supply of either Water or Gas pipes past other homes to the home where an incident has taken place.

Earthing systems have varied over the years from the once standard application of connecting the earth lead via the metal pipework of a cold water supply.

The introduction of plastic piping systems saw the introduction of an earth electrode commonly referred to as an earth stake.
An earth stake has limitations as to its effectiveness due to the electrical conductivity of the ground it is implanted in; ideally moist ground will provide a better earth

It remains standard practice today that where a cold water metal piping system is in place in a building the earthing system is still connected to both the metallic cold water piping and the earth stake.

Metal pipes for water or gas reticulation in a building were all that was available years ago and as both systems were of a metallic material earthing leads were inadvertently placed on gas reticulation pipework.

Corporation personnel who attended buildings where the earth lead was on gas piping would not work on the installation until an electrician had removed the earth lead and placed it on the cold water piping.

Similarly cold water and gas piping, particularly under a building can be like spaghetti with them laying over each other.

Then and as it is today you are your own Safety Officer it was the determination of the personnel on site if it was safe to work on the site.

Case histories on incidents or near incidents include seeing sparks jumping across from a gas meter to service and fitting lines and in days past from the meter or associated pipework to the metal casing of a meter box.