Categories?

May be a stupid question.

What do the categories designations mean? I.E. H1, H2, H13 etc . . .

I have 9003 bulbs and it seems like a endless number of possible categories.

Those are types of bulbs: H1 is a single filament bulb, H4 is a dual filament bulb, etc. I don't know if this answer your question?

Anyways, let's hear some admin or anyone experienced here.

hangn_9 said:

What do the categories designations mean? I.E. H1, H2, H13 etc . . .

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The 'categories' are a UNECE R37 thing, wherein

UNECE R37 and addenda
The term "category" is used... to describe different basic design of standardised filament lamps. Each category has a specific designation, as for example: "H4", "P21W", "T4W", "PY21W"or "RR10W".

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9003 is the "trade number" for what would be a category H4 lamp according to UNECE R37, and of type HB2 in 49 CFR 564 here in the U.S.

Ultimately, the use of the word "category" vs. "type" just seems to be a matter of diction.

I guess what I am trying to figure out. Do I have to replace with exactly the same"H" category as the original? Is one category more desirable than others? Or is it specifically dealing with Fitment? Is there a chart or listing that spells out what each possible 1 ,2 ,3 etc . . . means to a consumer?

hangn_9 said:

I guess what I am trying to figure out. Do I have to replace with exactly the same"H" category as the original?

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That's about the long and short of it.

Is one category more desirable than others?

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It depends on what the bulb is for. An H4 is undesirable in a front position lamp, and a P21W would be undesirable as a headlamp bulb. It seems you're ascribing too much importance with the lettering and numbering scheme as far as effectively imparting at a glance what that bulb is for and what its electrical and photometric performance really is. For example, the H3 might sound "higher" or "better" than the H1, but that's not the case. And H8 vs H7 similarly shows that greater humbers after the letter really don't tell you much.

Is there a chart or listing that spells out what each possible 1 ,2 ,3 etc . . . means to a consumer?

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UNECE R37 and its annexes could be somewhat helpful, if not also somewhat esoteric.

Each lamp is designed to use one kind of bulb. That decision is made when the lamp is being engineered. There are certain kinds of bulbs that can be replaced with certain other kinds in certain lamps without causing problems, but for the most part yes, you do have to replace it with the same kind. The number (H1, H2, H3, H4, etc) does not indicate better/worse or anything else about the characteristics of the bulb; these numbers are issued sequentially. H1 came in 1963, then H2 in 1964, then H3 in 1966, H4 in 1968-69, H5 and H6 exist in theory but were never adopted, H7 in 1992, etc. Meanwhile the US devised its own numbering system in 1983 with HB1 ("Trade number" 9004), HB2 ("Trade number" 9003) in 1992, HB3 (9005) and HB4 (9006) in 1985, and HB5 (9007) in 1991. Then the US authorities stopped trying to buck the system and the industry moved toward worldwide light sources so H13 is H13 all over the world, only someone (at Ford, I think) arbitrarily decided to call it "9008" even though there's no such trade number, so now there's a trade number 9008...confused yet? Replace the bulb in your headlamp with the same kind of bulb.