Generator Use & Safety

Spring is [hopefully] coming soon with expected turbulent weather.  A new hurricane season is also upon us.  Both are liable to cause disruptions to utility electrical power.  Annual ARRL Field Day is also approaching.  Time to think about auxiliary power generators.

Small gasoline-powered generators are relatively common and widely available for emergency or portable electrical power.  It’s a good idea for the prepared homeowner to have one, mainly to keep the fridge/freezer cold during times of sustained power outage.  The savvy radio amateur also recognizes the importance of communications capability in a blackout scenario as well.  Power is needed to make our radios work beyond what limited battery capacity we have, particularly in emergency situations.  Most EmComm groups include generators in their plan and have them on hand.  Not every ham does.

Honda Generator

Consider having a small generator for essential power when the lights are out for hours.  Having a generator is good; knowing how to use it safely is the focus of this topic.  We will look at four related safety considerations:

  1. Carbon Monoxide hazards— CO
  2. Fuel handling and storage (fire)
  3. Generator grounding
  4. Shock hazard

Carbon Monoxide (CO) is the primary hazard with generators, since  CO is produced in the exhaust of all gasoline and natural gas combustion engines. 

g0b04-2019

NEVER, ever run a generator inside a dwelling or garage where exhaust can seep into the occupied space.  CO is a colorless and odorless gas which can kill or injure humans and animals.   It can be detected only with chemical or electronic CO detectors; it’s wise to have detectors in every home.

E0A07-2016

Always operate a power generator outdoors in a well-ventilated area. Continue reading

Flat Ground Strap

Ever wonder why RF grounds should be flat straps and not regular wires?

This is because ordinary wires are not good conductors at frequencies higher than 50-60Hz. This complicates wiring and bonding requirements.

Impedance (effectively, AC resistance) of a conductor increases with frequency and length due to inductive reactance.  The higher the frequency, the greater the impedance.

XL

All conductors have some measurable inductance, and it doesn’t take much to yield significant impedance.  At KHz or MHz frequencies, long round wires might present hundreds or even thousands of Ohms impedance; not suitable for grounding.

A good ground has less than one ohm impedance.  This is a genuine safety issue.

G4C05-2015

Since inductive reactance increases with frequency and length, safety grounds and module bonds need to be something other than long round wires when radio frequencies are involved.

When high frequency grounding is required, use short, wide, and flat conductive straps.  The high aspect ratio minimizes electrical inductance vs. a round wire, as does a short conductor.  This lowers the ground wire’s impedance at higher frequencies.

T4A08-2018

So now you know.  Keep it flat and short (KIFS is a lousy acronym).

It’s not just a suggestion; this one might just bite you if you don’t heed the guideline!