H4, HB2, and 9003 bulbs Technical bulletin:

H4, HB2, & 9003 bulbs.

9003 and HB2 are different names for the same bulb, so these
Who may use HB2 or 9003
numbers apply to just two kinds of bulb: H4 and 9003/HB2. bulbs?
9003 or HB2 bulbs marked
“DOT” may be used in the US
they depend on the filament being very
and Canada in any car head-
precisely placed. If the filament is not lamp that is marked “DOT
precisely where it’s meant to be, the HB2,” and in any motorcycle
beam pattern will be shifted or changed. headlamp designed to take an
H4, 9003 or HB2 bulb. They
low beam
filament Like all engineered products, headlight can also be used in any car
bulbs are built to a technical standard headlamp designed to take an
high beam which specifies all mechanical, electri- H4 bulb.
filament
cal and dimensional aspects of the bulb.
This blueprint makes sure all bulbs of Who must use HB2 or 9003
bulbs?
a given type are interchangeable, and
Automakers must install only
provides allowable ranges, or manufac-
9003/HB2 bulbs marked
turing tolerances, for each aspect. “DOT” in the USA in head-
lamps marked “DOT HB2.” To
In 1991, automakers wanted to use H4 make sure such headlamps
headlight bulbs on cars in the US, but remain in compliance with
the DOT decided engineering blueprints Federal standards in the USA,
for H4 bulbs allow too much variance in use only replacement 9003
the position of the filaments within the or HB2 bulbs marked “DOT.”
9003 and H4 bulbs look alike, fit in bulb. So a new blueprint was made, with This is especially important in
all the same headlamps, have the same all the electrical and dimensional proper- areas where headlamp bulbs
are checked for “DOT” mark-
wattage rating and seem to be com- ties the same, but with stricter limits on
ings as part of a state vehicle
pletely interchangeable, but in some filament placement variance. Because of
inspection program.
places, the law says that only one or the the limits in the US on beam intensity in
other type must be used. effect in 1991, the maximum allowable Who may use H4 bulbs?
light output tolerance was also reduced. H4 bulbs may be used in H4
In 1971, the H4 bulb was introduced This new bulb specification was called headlamps, in any country
in Europe as the world’s first halogen “9003/HB2”, because at the time, two where such headlamps are
headlamp bulb that could produce both numbering conventions were in use. permitted on cars or motor-
low and high beam from a single bulb. It Many 9003/HB2 bulbs also carry the cycles. Outside the USA, they
quickly became the world’s most popu- “H4” marking, and vice versa, because may be used in headlamps
lar headlight bulb except in the USA, it is possible to meet the specifications designed to take HB2/9003
bulbs in areas where there is
where cars had to have sealed beam in both blueprints at the same time. The
no requirement or inspection
headlamps with non-replaceable bulbs. first headlamps with 9003 bulbs were on
for bulbs marked “DOT.”
Motorcycles in the USA have never been 1992 model cars.
required to use sealed beam headlamps, Who must use H4 bulbs?
and so the H4 bulb became popular for Filament placement variance is not a H4 bulbs with a circle-E mark
motorcycles in the US and worldwide. It problem with high quality bulbs made are required in many countries
is widely used to this day. by reputable companies. At Candle- outside North America.
power, we make sure all our bulbs
In 1983, the US Department of Transpor- are better than the law requires. Our
tation (DOT) first permitted cars in the filaments are all precision focused inside
US to use non-sealed-beam headlamps each bulb to ensure a properly placed,
with replaceable bulbs, but DOT require- properly formed beam in any headlamp.
ments differ from those in force outside In areas where there is no legal prefer-
the USA. One of the US requirements is ence for 9003 bulbs over H4 bulbs in
that the beam aim must not change when cars, any Candlepower H4 or 9003 Candlepower Incorporated
a bulb is replaced. This can happen if a bulb can be used with confidence in any 14626 Southlawn Lane
headlamp. Rockville, Maryland, USA
low quality replacement bulb is installed,
20850-1317
because in a poorly made bulb, the
filament is often improperly positioned. ph 301.340.0224
T002.01

Headlamps are optical instruments, and fax 301.762.2518

www.candlepowerinc.com
Copyright © 2003 Candlepower Inc. Illustrations are for visual ID only and do not imply interchangeability.