alarm
alert
arrow
background
battery
black
blank
careful
caution
charge
danger
dangerous
electric
electrical
electricity
energy
flash
grey
hazard
hazardous
high
illustration
industrial
industry
label
lethal
light
lightning
power
powerlines
protection
protective
risk
safety
shock
sign
station
substation
symbol
technology
threat
transformer
triangle
volt
voltage
warning
watt
wattage
yellow
zone