[HCARC] Last nights presentation

[k5hab at arrl.net]

Dear fellow members
Jim Froemke’s, K0MHC, presentation last night was great, informative and had a lot of enthusiasm.  It also has some really wrong information.  Like life and death information.
You cannot use a cigarette plug for power.  
Here is a picture of a Cadillac Escalade dash after a 100 milliamp GPS was plugged into the cigarette light with a 1 amp fuse.




There is another photo of a Chevy Suburban, which I do not have a copy of, showing the burned interior and a child’s arm.  This was caused by a laptop charger plugged into a cigarette outlet. The child died.
The number one cause of car fires, after accidents, are cigarette plugs. The problem is not that the plug is not fused for say 10 amps or that the 16 gauge wire will not carry the current.  It is that one amp at 12 volts will generate 12 watts of energy or heat and melt the wire.

Hear with permission is a quote from K0BG’s excellent website:

Do Not Use Existing Vehicle Wiring

Never, ever use existing vehicle wiring to power any amateur radio gear. This includes fuse taps, and so-called accessory sockets, aka cigarette lighter sockets! In part from the National Fire Protection Association <http://www.nfpa.org/>, sub-section 15-3.2.1:

Overloaded Wiring. Unintended high-resistance faults in wiring can raise the conductor temperature to the ignition point of the insulation, particularly in bundled cables such as the wiring harnesses or the accessory wiring under the dash where the heat generated is not readily dissipated. This can occur without activating the circuit protection. 

There's rarely a single cause for any given car fire, even if an investigator can trace all the way back to the incident that sparked the blaze. It's more likely that there was a combination of causes: human causes, mechanical causes, and chemical causes, and they all worked together to create an incredibly dangerous situation.

The process is called thermolysis (aka pyrolysis). It is the decomposition of the insulation covering the wire, brought about by high temperatures—resistive heating in other words. Thermolysis may occur within a few minutes, or over an extended length of time. Ignore this rule, and your vehicle may end up looking like a burnt cinder!


We all plug in our phone chargers, our computer chargers, our radar detectors, our GPSs and on and on into cigarette lighters.  Do not do it.  Wire directly and do not use a cigarette lighter for any electrical connections.

I will address the PVC antenna support tie raped to the cargo rack when I calm down.
Please stay safe out there.  
73
Peter
K5hab