alarm
alert
area
arrow
attention
background
beware
black
bolt
careful
caution
construction
danger
dangerous
death
electric
electrical
electricity
energy
fence
forbidden
graphic
hazard
high
icon
illustration
industrial
industry
information
isolated
keep
label
lightning
notice
power
protection
red
risk
safety
secure
security
shock
sign
symbol
volt
voltage
warning
white
yellow