Presented to the SFPE
January 13, 2014
Paul McCoy, P.E.

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• Paul McCoy is a graduate of IIT - Electrical Engineering
Licensed Professional Engineer in State of Illinois
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Former senior executive at ComEd
• Included close relationships with the Fire Service both in Chicago and suburban areas
Co-developed the ComEd Safety Village
Established first-in-nation outfitting of workforce with fire-retarding clothing
Worked extensively with the MABAS structure
Extensive “hands on” work with all classes of electrical equipment, controls and system protection technology including trouble analysis, system analysis and project commissioning on equipment from 480 to 765,000 volts
• Includes extensive understanding of the effects of electrical contact and the human body
Extensive operations, operational analysis, commissioning, and energy policy experience
Co-founder of several industry organizations
Currently a director or principal with several companies

• What is a “power surge”?
• Caused by nature
• Caused by the utility or within the end-user environment
• Why are some dangerous and what causes this?
• Is there a “signature” that can be rapidly recognized?
• What kind of damage is caused?
• What should a first responder look for?
• Assessing risks
• Can they be mitigated?
• Wrap-up and questions

• An elevation in service voltage
• Can be a shortlived “spike” or a series of same
• Generally lasting just a few thousandths of a second
• Longer-lived voltage elevation caused by utility equipment failure or mis-operation
• Lasting for sizeable fractions of second or longer
• Generated from inside the home

• Lightning is the only common natural cause
• Characterized by an almost instantaneous rise in voltage of short duration
• The steep rise in voltage (far faster than normal utility frequency) can cause some bizarre things to happen
• It’s a function of packing substantial energy into an extremely short time
• Stories are legend about the effects on structures, electrical equipment and humans
• All utilities protect themselves (and us) from the vast majority of damage – but nothing is perfect
• A big factor is exactly where the lightning strike occurs
• Effects dissipate rapidly with distance so usually affects just a few homes or businesses (per strike)

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• Total flash duration:
Number of strokes/flash:
Stroke duration:
200 - 300 ms
3 – 5
50 70 µs
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• Interstroke interval:
Current:
Total charge transfer:
• Total flash energy:
60 ms
50 – 300 kA
20 – 200 C
10 9 – 10 10 J
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This is total cloud to ground energy
A fraction of this is delivered to what is “struck” on the ground

• 4 kJ equals the energy in one gram of TNT
• 1 MJ will easily melt one pound of steel
• 2 MJ will easily vaporize that same pound of steel

• Caused by switching
• Capacitors (devices that control voltage)
• Maintenance
• These are generally harmless in the context of what we are concerned about in this discussion
• Can also be caused by your “neighbors”
• Starting and stopping of their air conditioners, etc.
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Industrial processes like welding, large air compressors, elevator motors, and on and on
These are also generally harmless in the context of today’s discussion (but can be really irritating)
• Then there is the category of sustained elevated voltage, which can cause substantial damage

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Source: www.nerc.com
The “grid” can be broken down in to four main components:
Generation, Transmission, Distribution, and Load
This diagram is a basic overview, but does not truly illustrate the
HIGHLY interconnected nature of the transmission system.
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• Voltage above normal.
• Significantly above-normal voltage will cause real damage !
• While voltages don’t reach lightning-strike levels, the total energy available at the home service entrance is actually considerably larger and of longer duration
• This is almost always caused by the utility if you are a residential customer

• Failure of voltage regulation devices and/or controls at the substation or on the distribution line
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• Can lead to over-voltages of 10-20%
Can cause premature appliance failure
• Can cause overheating of end-use equipment
• Or it can occur when a power line of higher voltage contacts a line below it of lower voltage (hardware failure)
• This can raise the lower voltage line to that of the higher voltage line for fractions of a second or longer
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• This can produce voltages double or more of normal
• Internal home damage can be immediate and widespread
“Signature” – multiple homes/businesses with damage all at the same time

• Anything electronic
• If lucky, limited to power supply
• Appliances
• Control panels and compressor/motors
• HVAC
• Controls, motors, contactors
• This damaged equipment can be the source of fires if the enclosure doesn’t contain hot material

• Extremely high voltage can also cause:
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• Exploding light bulbs
Destroyed surge protectors (both plug-in and whole-house)
• Energy being dissipated is beyond rating
Destroyed plug-in timers and dimmer switches
Sparking outlets
• All of these have the potential to cause fire, especially if they are near/under curtains, bedding, on rugs, under upholstered furniture.
• Except in extreme cases, relatively modern house wiring and the main panel will fare the best (modern wiring is rated at 600 volts)

• After obvious checks for smell/smoke
• Check electronics
• Surge protectors
• Timers/dimmers
• Unless smell/smoke indicate, metal-enclosed appliances, other metal-enclosed utilization equipment and the main/panel may be best left to the end of your “sweep”.

• In particular look for “hidden damage”
• The bottom of surge protectors
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Hidden timers
If any bulbs have “popped” check all the closets, crawl spaces, etc. for any potential incipient fires
• If the house is without power, check the main panel
• If the main breaker is tripped, don’t close it without an internal check of the main panel by someone qualified
• Evidence of wiring, main panel, outlet or wall switch damage should be cause to require a detailed check of house wiring and other equipment by someone qualified
• I’d have everything checked anyway (includes the entire HVAC system)

• For utility-induced extended high voltage there is no foolproof mitigation
• Surge protectors can help, but cheap ones provide little or no protection
• Whole-house protection helps a lot.
• Can be pricey
• Be prepared for the protection to sacrifice itself to save the house equipment – so how it is installed/mounted is important
• Here, again, you get what you pay for
• Still need point-of-use surge protection

• Coordinates with the whole-house unit (which has a higher voltage clamping rating)
• Think of these working as a “waterfall”
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Adds additional energy dissipation capability
This is a case of “you get what you pay for”
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• Higher cost units usually have higher energy dissipation ratings (up to 3500 Joules)
What many don’t know is that surge protectors have an expiration date (generally about 5-7 years from date of purchase) – it’s stamped on the back
• Every surge they “clamp” takes life from the unit
• Top-of-the-line whole house units have replaceable energy dissipation surge blocks

• Instances of extended high voltage are rare
• But when they occur significant damage is possible
• Damage is reduced with a good electrical installation and quality surge protectors (whole-house and point-of-use).
In these events expect the service-entrance surge protector and point-of-use surge protectors to sacrifice themselves.

Contact Info: mccoy@mccoyenergyconsulting.com