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Re: TR4 Headlight Switch with New Sealed Beams

To: sanborn@net1plus.com, triumphs@autox.team.net
Subject: Re: TR4 Headlight Switch with New Sealed Beams
From: DANMAS@aol.com
Date: Mon, 10 May 1999 17:26:07 EDT
In a message dated 5/8/99 7:59:52 PM Eastern Daylight Time, 
sanborn@net1plus.com writes:

>  new harness.  I
>  installed these new Sylvania X-travision halogen sealed beams. They are
>  modern 55/60 watt units instead of the original 30 or 35 watt ones.   
<snip>
>  I was concerned about whether the old electrical components would carry the
>  load of the new sealed beams.  
>  
>  Do I need to wire in the relays or will the old switch and the new harness
>  carry the load.

Brian,

The headlight wires on your car are *probably* rated for 8 amps. The old 
lights pulled a maximum of 6 amps, while the highbeams on your new lights 
will pull 10 amps. Fortunately, the wire ratings are conservative -- ie, they 
won't melt with 8.1 amps.

Whether or not you can get by with the existing wiring is a judgement call. 
If you still had the old wiring, I would say definately not, but with a new 
harness and all the associated new connectors, you probably can. The wiring 
harness on my car was not new, but it was cleaned well, and suspicious 
connectors replaced when it was restored about 11 years ago. When I got the 
car, it had the 55/60 watt headlamps, and they have been there ever since, 
with no problems.

I'm only guessing at the wire gauge for your TR4, so it could be smaller than 
the TR6. Triumph typically used wires about one size smaller than the 
*correct* ratings, so your wiring may only be rated for 6 amps.

I wish I could give you a more definitative answer, but there are so many 
variables, both in the car's wiring scheme and in the wire ratings, that's 
it's hard to do. Theoretically, you should use the relays. If you should go 
that way and need any help with wiring diagrams, let me know.

As additional info, in an emergency once, I ran my car's entire electrical 
load, including headlights, through a 16 gauge wire, rated for about 8 amps 
or so, for about an hour. I held the wire in my hand the whole time to 
monitor the temperature. It definately got warm, but never actually what you 
would call hot.

Dan Masters,
Alcoa, TN

'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
                    http://members.aol.com/danmas/
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74

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