Remains of the broken glassReplacement fireplace shown properly installedExample of the labelsLabels located in this concealed space
Fireplace Acts Like Improvised Explosive Device
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The renovation of a century old house included a modern gas-log fireplace normally ignited by activating an electrical switch on the adjacent wall. The owner turned on the switch and knelt to see why the gas had not immediately ignited and received a face full of pellets as the tempered glass door shattered from a gas explosion. The injuries were severe enough to merit a claim against the fireplace manufacturer.
The assignment requested an evaluation of possible design, construction and/or labeling deficiencies that would support a law suit.
• Why did the fireplace fail to ignite initially?
• Don’t gas devices have a time delay on flame failure?
• Why was the owner’s face in front of the unit?
• Were there any safety instructions or warnings?
Documents, specifications, photos, and medical and incident reports were reviewed after the site visit. Unexplained ignition delay caused the gas to explode. The investigation then focused on the choice of ignition controller, and instructions and warnings provided by the labels affixed to the fireplace.
National design standards required that the fireplace have a time delay lockout, either separately or internal to the gas control and ignition module, activated upon failure to ignite. This fireplace did not have that required safety function. Further the designer must anticipate all predictable uses and misuses of the device. The labels assumed a rational operator with agility, visual acuity, and some critical analysis skills. The design failed to account for use by the old and infirm, and by normal, capricious or underage children.
Some manufacturers seem to believe that they can solve safety or complex design problems with the liberal application of instruction and warning labels. Often these notices seem to have been written, not by safety professionals, but rather by attorneys, or foreign manufacturers with limited command of the language or the operating conditions of the device or appliance. (In another case, a manufacturer was found liable for an otherwise adequate warning label, just for not testing the effectiveness of that label.)
Many warning and instruction stickers adorned the “fireplace.” However none were visible during normal operation. Their content indicated that the designer/manufacturer knew of the danger of explosion if the firebox was allowed to fill with unignited gas.
At a nominal additional cost, electromechanical gas controllers are available that will automatically force delay of any possible restart attempt upon ignition failure.
The warning and instruction labels were located in a concealed space below the fireplace, accessible after tilting a grill forward and down. The labels were vague, confusing and impractical, with no external indication of their existence or location. Hanging an instruction booklet on the wall beside the fireplace was impractical. The case settled for the plaintiff because the selection of the gas control valve without a delay timer was a design defect, and the labels inadequately instructed and warned.
Lets look at the labels to get an idea of what not-to-do when creating instructions and warnings.
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This is how the finished fireplace looks when installed. Control of the gas and ignition is through use of the wall switch vaguely visible between the fireplace and the window. This switch has the same style as an ordinary room light switch. An additional problem occurs because we routinely operate such switches with no need for concern about sniffing for gas, explosions, or waiting times. Such a switch, though electrically appropriate, belies the additional danger inherent with the gas fireplace.
Though “safety glass” is wonderful for car windows and sliding doors because it eliminates the danger of long sharp shards that can induce deep gashes during an accident, it turns the common home fireplace into a fragging grenade if an explosion occurs. For this reason, exceptional attention to design details becomes imperative.
The second instruction is “Open control access panel.” The panel covers the instruction so how are you to know about the instruction?
“WARNING: IF FIREPLACE DOES NOT LIGHT ON FIRST TRY WAITING 5 MINUTES BEFORE TRYING AGAIN. IF FIREPLACE STILL DOES NOT LIGHT CONSULT TROUBLESHOOTING GUIDE OR CALL FOR SERVICE.”
Do they think old grandma, left just for a few minutes while you ran to the store, or the fascinated kindergarten kids who ran in ahead of you while you unloaded groceries, are going to 1) find this label, 2) understand the erroneous grammar, or 3) assume that the suggestion “try waiting” is really meant to be a command, “do not attempt to light for five minutes?” The importance of this warning is Life or Death! How would your international visitor with limited understanding of English interpret this warning, even if it were otherwise in plain sight?
“B. BEFORE OPERATING smell all around the appliance area for gas. Be sure to smell next to the floor…”
Could you fault the subject owner for having his face in front of the unit? Was he merely following instructions? How many users of a gas fireplace would get down on the floor and sniff before turning on the switch? An automatically delayed controller would eliminate the need for this procedure and eliminate the uncertainty of predicting the user’s behavior.
“WARNING: if you do not follow these instructions exactly, a fire or explosion may result causing property damage, personal injury or loss of life.”
It was impossible for the manufacturer to claim that they were unaware of the hazards while having this warning affixed to their “appliance.” It's as if they used the same standard set of warning labels for all products that they produced.
The fireplace appears like this before installation. Unlike some generic factory production machine, all its surfaces disappear behind the wall, and warning labels are inappropriate for the front “finish” surface. This product is not a candidate for solving any “danger” problems with the use of warning or instruction labels. Further it is unlikely that most of the predictable users would find and read an instruction or owner’s manual before attempting operation.
The labels are located behind an air grill whose louvers, in normal operation, are angled, preventing the user from discovering the labels behind. Further it takes auxiliary illumination (like a flashlight) to read them, assuming they are still legible after the construction debris, and all the normal accumulation of dust from the convection flow of heated room air, have taken their toll.
The current “in vogue” term for this is TMI (too much information). In a world where many digital products now do not even include paper instructions, users have become trained to “just try it” until it is figured out. This is where we might suspect that defense attorneys rather than industrial designers specified the content and placement of these labels. Yes, they are there. No, they do not, as a practical matter, serve their intended function. In this case, there was no labeling substitute for designing and selecting the proper gas controller with a built-in delay timer.
This is the igniter and gas valve controller. It also has a “WARNING” acknowledging that explosions can occur. It makes a vague attempt to suggest, perhaps, a need for a safety lockout timer, maybe external, sorta. See “Reset Lockout Thru Safety Switch” at the bottom of the label. This represents a vague, nonfunctional instruction. Or is it a warning? Did this tell me that I need to design and install an external lockout? Or did it infer no need to worry as the lockout is built in? Or maybe if the fireplace doesn’t ignite because this controller has locked it out, try flicking the on/off switch for a reset?
In fact there is no timer in this unit, and there wasn’t one incorporated externally within the overall fireplace controls, either.
Can you imagine getting down on your hands and knees, pulling down this grill, and reading the warning labels each time before lighting (assuming that your old-person’s reader-cheater glasses will even focus within that space)?
There are a lot of human factors to be considered when designing a consumer product, or even an industrial machine.
A designer would be well advised to have their designs reviewed by a safety engineer, or human factors expert, preferably one with forensic experience.
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Fire Cause and Origin
Power Wiring and Circuits
National Electrical Code (NEC)
General Order 95
Electrician Trade Practice
Lock Out / Tag Out