Interpretation ID: 2781y
1686 Lighthouse Hill Road
Homer, NY 13077
Dear Mr. Bonvallet:
This is in reply to your letter of October 5, l990, with respect to a prospective headlighting system. It is contemplated that the lower beam on the system would be furnished by a gaseous discharge headlamp, an "integral beam" headlamp under Standard No. l08. The upper beam would be furnished by a replaceable bulb headlamp using an HB3 light source.
You comment that a combination system such as this is not specifically addressed by Standard No. l08, and you ask for confirmation of your opinion that the photometric requirements of Figure l5 would apply to both the upper and lower beam headlamps.
At the present time, such a hybrid headlighting system is impermissible under Standard No. l08. The standard establishes separate requirements for integral beam headlighting systems (S7.4), and for replaceable bulb headlighting systems (S7.5). Though "integral beam headlighting system" is not specifically defined by Standard No. l08, such a system would appear to be one that consists of integral beam headlamps. Standard No. l08 does define "integral beam headlamp", and that definition specifically excludes "a replaceable bulb headlamp" such as one containing an HB3 light source. Similarly, a "replaceable bulb headlamp system" is one that consists solely of headlamps containing HB1, HB2, HB3, HB4, or HB5 light sources.
It is true that Figure l5 is one of three lower beam photometric options that apply to an integral beam headlamp, such as one producing illumination through gaseous discharge. However, under the language of the standard, Figure l5 applies when the lamp is used in a four headlamp integral beam headlighting system (S7.4(a)(l)(i)). It is also true that the upper beam photometrics of Figure 15 apply to an HB3 replaceable bulb headlamp (S7.5(e)(3)(ii)), but only when used in a four lamp headlighting system in which each headlamp contains a single replaceable light source.
As you know, the policy of this agency for the last decade has been to reduce design restrictions on headlighting systems. Removal of the implicit prohibition against hybrid headlighting systems would be a further step in this direction. If your client is seriously considering such a system, it may submit a petition for rulemaking at the appropriate time.
Sincerely,
Paul Jackson Rice Chief Counsel
ref:l08 d:12/24/90