During 2005, we spent numerous articles describing a seven-point size-up to increase firefighters’ abilities to size-up buildings before they commit themselves to a structure for firefighting operations, which are normally conducted inside a structure that is being weakened every minute a fire is burning. Although firefighters are injured and killed every year as a result of interior firefighting operations, firefighters are also injured and killed every year as a result of exterior firefighting operations. Therefore, it is imperative that every person on the fireground continually look at a building that is exposed to fire (remember: buildings exposed to fire are really buildings going through a process of demolition) to determine the strengths and weaknesses of a building and if the building will give you the necessary time to do whatever you are planning to do in a safe manner. The Reading A Building archive can be found HERE.
The “Reading A Building” series covered numerous aspects of analyzing facets when “reading a building”. Remember there can be more to a building than concrete and wood. With these thoughts in mind, let’s briefly consider gas and electrical utilities, and specifically a few that vary from the “norm”.
If you have never noticed this type of gas meter, look at the back or side of any Olive Garden restaurant. This gas meter is known as a rotary vane meter and has a significantly different appearance than the typical residential gas meter. When an occupant uses more natural gas than a typical gas meter can handle, a rotary vane gas meter is used. This is an indication that the interior of the occupancy is using natural gas in a quantity that would not be “normal or typical”.
In this photo, there are two wires entering the structure instead of the modern and common three wires (or triplex). This electrical configuration is known as duplex and was used until it was replaced by the modern triplex configuration. This is an excellent indicator of “knob and tube” wiring, and is also an excellent indicator that balloon frame construction is present as both of these configurations were used during the same periods. Prior to triplex, duplex was the standard wiring configuration and consisted of two wires that traveled through a structure suspended on ceramic insulators and passed through ceramic tubes when traveling through a wall or plate. Unfortunately, this can present a significant hazard to a firefighter involved in suppression operations, specifically overhaul. As this type of wiring is now quite old, the insulation is brittle, and in some cases, has fallen from the wiring leaving bare wires. If this type of wiring is present, shutting off the electrical utility should be an initial priority.
This picture shows two different styles of natural gas risers that are visible from the ground to a gas meter. In the top picture, the riser has a ring, and in the bottom picture the riser has a washer. Why the ring and washer? The ring indicates a branch service and a washer indicates a plastic pipe has been inserted inside an older metal pipe. A typical branch service can be found at the rear of mini-malls. These structures have numerous occupancies inside one building. Each occupancy is fed by a separate gas meter that has its own shutoff. However, each meter is connected to a branch main that is in turn connected to a main in the street. This connection also should have a shutoff. So, this configuration presents responders with multiple opportunities to shut of the flow of gas. When plastic pipe is used or plastic is used inside an older metal pipe, the chance of the plastic breaking/cracking with a resultant leak is greater than with a plain metal pipe. Remember that a green band on the riser near the stopcock valve indicates the service line is all plastic which can increase the possibility of breakage and a resultant gas leak.