Forensic Engineers and Consultants

Archive: Residential

How Long Before the Pipes Freeze?

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An unexpected severe winter freeze will remind many people and businesses that when water in a pipe freezes, the ice will expand and burst the pipe or pipe fitting.  Large losses will result from flooding when the temperatures rise.  Insulation will help, but not prevent freezing.  Insulation simply slows down the rate of heat loss.  The time of exposure to subfreezing temperature is an important factor.

The American Society of Refrigeration and Air Conditioning Engineers (ASHRAE) Handbook of Fundamentals has a short entry on the topic (Chapter 23, page 23.5-6), which gives an equation for estimating the time that it will take an insulated pipe to freeze, Read More

Lack of HVAC System Design and Poor Installation Lead to Extreme Conditions

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Construction defects can appear in many forms.  The building does not necessarily have to fall down. There are many types of construction defects, including roof leaks, water intrusion into walls, as well as Heating, Ventilation, and Air Conditioning (HVAC) defects.

One extreme example of this was an office complex I was called to for an investigation of the source of mold observed on the walls.  The occupants complained that they could not find a temperature setting on the thermostat where they could make the office comfortable. When I inspected the office, I couldn’t believe what I was seeing.  A band of black mold Read More

Heavy Machinery Fires Caused by Hydraulic Hose Failures

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Heavy machinery fires are often caused by hydraulic hose failures.  Pressurized hydraulic fluid escaping from a failed hose assembly can be atomized into a fine spray that can be ignited by heated engine surfaces such as the engine exhaust or turbocharger.

Hydraulic hoses near the engine compartment of an excavator that burned.

 

Hydraulic hoses often fail due to age and wear, requiring regular inspection and replacement of hydraulic hoses to prevent failures. Hoses may also fail if they are misrouted.  Misrouting can lead to the hose being pinched or causing it to chafe against a sharp metal surface. Read More

TVSS or SPD … Can I Buy a Vowel? Understanding Surge Protection and the Changing Requirements

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Surge Protective Devices (SPD), formerly known as Transient Voltage Surge Suppressors (TVSS) have been around for a long time.   The most recognized version is integrated into outlet strips and used to protect sensitive electronics from surges, or higher than expected voltages on the power line.  Early versions of these surge strips were known to have problems where internal components could overheat and cause a fire.  Thermal protection was added to the designs to greatly reduce the potential for a fire hazard.  Such an implementation in an outlet strip is considered a Type 3 SPD. Read More

The Condensate System – An Important Item in Routine HVAC Maintenance

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HVAC systems are almost everywhere in the United States now.  As a life-long resident of the humid south that grew up in a home without central air conditioning; I definitely appreciate the ability of a well-designed and maintained HVAC system to remove the oppressive summer humidity.

The very humidity that makes your clothes damp with sweat and hastened the invention of cooled leather seats in automobiles also has another route to create havoc…condensate.

In order for an HVAC or “air-conditioning system” to reduce the humidity in the air of your home or office it must first cool the air down to a point where the air can no longer keep the moisture in suspension as water vapor.  The moisture must condense… creating condensate.  This is what is happening when your cool beverage of choice “sweats” on the exterior of the container in the humid summer. Now that you have liquid water, as opposed to water vapor, this condensate must be directed out of your conditioned space to prevent water damage due to backed up or leaking condensate. Read More

In a Flash – The Transfer of Energies in Our Global Electrical System

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According to published weather data for the year 2019, 2.35 billion lightning strikes were recorded across the world, with 223 million of these in the United States.  The movement of atmosphere causes electrical charges to build up between clouds.  A tipping point is reached where the insulating properties of the air cannot withstand the level of energy and a discharge occurs.

Image Credit: Charleston Post and Courier. A lightning strike over Charleston, SC on July 3, 2019.

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Congratulations Tom Kelly on CESCP Certification!

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Congratulations to Tom Kelly for completing his Certified Electrical Safety Compliance Professional designation. The National Fire Protection Agency (NFPA) program, CESCP, is designed to meet the needs of electrical and safety professionals who oversee electrical safety programs or who manage electricians and other personnel exposed to electrical hazards.

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Improper Hearth Extension Leads to Structure Fire

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The fire service affords you the opportunity to witness and observe things that a lot of engineers and even most people do not get the chance to see.  An example of this is the situation where extended elevated temperatures combined with poor construction techniques to result in a structure fire.

I have personally observed several occasions where a structure fire was initiated due to improper construction of the fireplace hearth extension.  The most recent one followed a multi-day cold snap, at least by South Carolina standards.  The thermometer read 17 degrees F as I drove to the call of smoke in a residence Read More

Major Causes of Wood Truss Failures

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Wood truss failures can vary and identifying the cause requires visual inspection as well as a working knowledge of the structural loads and building codes. These truss systems must transfer the gravity and lateral loads to the foundations. Consequently, the framing system and the foundation provide strength and stability for a structure. The most common type of wood-framed construction uses roof trusses, exterior and interior load-bearing walls, beams, girders, posts, and floor framing to resist the gravity and vertical loads. This type of wood-framed construction engages a system of horizontal diaphragms (roof and floors) and shear walls (vertical exterior sheathed walls) to resist the lateral loads. Read More

Residential Structure Fires

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The winter season is well underway in the United States, with the Christmas and New Years holidays behind us and the depths of cold weather here for the duration.  With winter, many people spend more hours indoors as compared to the summer when outdoor activities ramp up.  With more time spent indoors, it is somewhat intuitive that the use of electricity would increase as well.

Electricity is one of the most influential utilities in our daily life.  Much of what modern societies rely on to get through a normal day requires electricity.  Have you ever been in a slight panic looking for an electric outlet when your cell phone is below 10% charge?  Or how many times do we all attempt to turn on a light switch when we enter a room during a known power outage from sheer habit?  Even our personal transportation which has relied on gasoline for roughly 100 years is shifting toward electric automobiles. Read More

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