advice
ahead
alert
arrow
attention
background
black
board
cable
careful
caution
danger
dark
death
electric
energy
forbidden
gray
hazard
high
icon
industry
inform
isolated
lightning
notice
old
orange
power
protect
risk
safety
security
shock
short
sign
signal
signpost
supply
symbol
technology
text
thunder
triangle
voltage
warning
web
white
wire
yellow