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Wiring for two front Driving Lights?

Chet Zerlin

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Hello all,

I'm planning on installing two 7" driving lights to the front of my 100-6 Healey and wiring them to an existing switch already installed by the PO on the dash. There is no wiring currently installed so I will also need to connect to a power source. What's the best way to wire these lights to that switch and power? My existing fuse box looks really "full" :smile: Will I need some type of relay?
I'd like to make them "active" only when the other lighting circuit is active too.

Any suggestions or information would be greatly appreciated.

Thanks!
Chet
 

Csarneson

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So it sounds like you want this switch to be in series with the standard headlight switch.

To do that you need to take another new wire off your headlight switch on the switched side to your PO switch. From there a wire from the switched leg of your PO switch to a new relay. Your relay should probably be fed from a 12-gage wire coming from your left side of your fuse box or some other non-fused battery power. I'd put an inline fuse on that wire. Then just feed a new wire from your relay switched leg to your new lights. I'm a big fan of using relays and big gage wire to high-amp draws and long connections.
 

steveg

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Once again inserting a plug for Tom's Toys color wiring diagrams. These have a very high usefulness to cost ratio:
https://tomsimport.com/category/new-parts/wiring-diagrams/

screenshot.1782.jpg
 

Keoke

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You can tie the existing PO"s switch to the same [R/W } hot lead to the head light switch , then install a relay in the engine compartment
close to the front of the car. now bring a hot lead { Brown } from the starter solenoid to the relays fixed terminal of the relay then
switched terminal can be wired to your driving lights a fuse in each of these leads is suggested- JAT
 

RAC68

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Hi Chet,

drawing power through your existing wiring harness will put an added strain on all components in series and the under rated wiring. I would draw a separate power line from your voltage regulator and separately fuse that line to 3 relays serving high, low, and driving lights. Properly connected, power would be drawn through the new line with your original harness and its components, along with separate driving lights switch, supporting the low power draw needed for switching the relays. The relays can be mounted on the left access panel inside the right wheel well and where headlight wires come together.

I have attached my setup as an example but you can alter the setup to align with your thoughts and requirements.

https://drive.google.com/file/d/0Bx...NWRiLWFkMTYtOGMyYTgwYTQ5Y2E5/view?usp=sharing

Enjoy your Healey,
Ray(64BJ8P1)
 
OP
C

Chet Zerlin

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Quick follow up. If I wanted to have this switch as a separate circuit and not dependent on the headlights being on could I draw power from the non-fused side of the fuse box instead of the headlight switch?
 

steveg

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Quick follow up. If I wanted to have this switch as a separate circuit and not dependent on the headlights being on could I draw power from the non-fused side of the fuse box instead of the headlight switch?

Chet - check out Ray's schematic. Your only difference would be the switching line would go from the output side of the ignition switch to the PO switch to the 85 terminal on the relay.
 

steveg

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Ray and Keoke - People say put the relays close to the lights. This means you have a relatively long heavy gauge always-hot wire going to the relay. If the relay is closer to the source, say, near the solenoid, you have a shorter, less vulnerable, hot wire and a relatively long heavy gauge supply wire to the lights.

Is there a difference? Am I missing something?

Edit: is this it?: If you have multiple relays up front you only run one long hot wire to them. Multiple short wires to the various lights. No difference if 1 relay; more efficient if multiple relays.
 

Keoke

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Quick follow up. If I wanted to have this switch as a separate circuit and not dependent on the head lights being on could I draw power from the non-fused side of the fuse box instead of the headlight switch?

That is what the method I spelled out accomplishes the { R/W} wire is simply a hoe bus that excites the head light switch the switch does not preform any function in the driving light control.
 

Keoke

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Put the relay on the shroud support braket Steve in the engine bay.-OK
 

Keoke

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Ray and Keoke - People say put the relays close to the lights. This means you have a relatively long heavy gauge always-hot wire going to the relay. If the relay is closer to the source, say, near the solenoid, you have a shorter, less vulnerable, hot wire and a relatively long heavy gauge supply wire to the lights.

Is there a difference? Am I missing something?

Edit: is this it?: If you have multiple relays up front you only run one long hot wire to them. Multiple short wires to the various lights. No difference if 1 relay; more efficient if multiple relays.

No putting the relay on the left hand shroud support bracket in the engine bay will address that concern.

No adding components reduces reliability.
 

vette

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Hello folks, sorry to bring in some counter points to the general consensus here but YOU DONT NEED RELAYS. In my opinion there is entirely too much use of relays in the LBC world. People get them misused, misinstalled, poorly grounded, etc, etc and then they have more trouble and alot of spagetti wires all over the place. Generally the running lights used as Fog or Driving lights such as the Lucas ones seen in Moss HAVE NO MORE THAN 60WATTS. On 12 volts that equates to 5 amps each so 10 amps for the circuit at best. You don't need a relay for 10 amps. Use a piece of 14 or 12 gauge stranded wire and it will handle 10 amps easily. Some say well you are protecting the small switch with a relay. I have been running my fuel pumps, driving lights and OD on 20amp toggle switches for years with no problems. Now as to your source of power. Just as a side bar, I have an 8 pole fuse block installed under my dash above my foot pedals which provides me with many points to pull another fused circuit if I want to but, If you are running the original 2 fuse fuse holder out on your firewall then know that the bottom fuse is the largest at 50 amps and it is almost doing nothing. Most of all the cars electrics are run off the top fuse which is a 35 amp fuse. the bottom 50 amp fuse was designed to be used for accessories such as radio, cigarette lighter, horns and of all things RUNNING LAMPS. If you have an early 100/6 the 50amp bottom fuse has two brown/green wires on one side of it. These go to the horns. If you have a later car you probably have just one wire on that side of the 50 amp fuse and the one wire goes to both the horns. I should be purple. But here's the deal, that fuse is fed by a brown wire. That brown wire comes directly off the "A" terminal of the voltage regulator which is fed directly from the battery terminal at the starter solenoid. You can't get much cleaner power than that. But too on that same era of Healey, the 100/6, the head light switch is powered directly off the A1 terminal of the voltage regulator with a brown/blue wire. But i would stay away from the headlight switch because it already is loaded up with a lot of current and I would not add another 10 amps to it. So the easiest way and one that will be trouble free by the KISS method (keep it simple stu...) is to attach a 14 or 12 guage stranded wire to the load side of the 50a fuse and run it to a 20amp toggle switch and then to the lights. Bingo, done. If you feel that the 50amp fuse already has too much on it, example being, horns, radio, etc. then you could attach your source wire to the feed side of the 50 amp fuse and use a 10amp inline fuse holder to fuse your new wire. Or the most direct source from the battery is the "A" terminal of the voltage regulator. Put your source wire on there with an inline fuse hold and a 10 amp fuse. In the pic of my fuse box you might notice that the only 10 amp fuse I have is on the OD. This has been working this way for years and I have no relays in my car.
 

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RAC68

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Hi All,

Steve,

I believe the placement of the relays should be reasonably close to the source of power for the reasons you mentioned. To satisfy that requirement, I had installed the fused power line as a takeoff on the alternator and connected the relays through a reasonably short oversized 10-gauge line. The 3-relays were installed on the access panel as a convenient location where the original wiring and circuits terminate. Keep in mind that when retrofitting relays, you need to keep space, convenient access, and original wire terminations in mind. Other then the many in-line fuses I have installed, I want to retain the ability to (reasonably easily) return to Concourse by removing any modification made (probably not in my lifetime). I still have the original harnesses (though rewrapped in approx. 1986).

Vette,

As mentioned, I have original wiring within rewrapped harnesses and find the stranded wire within to be quite thin. Also, all power to lighting passes through the light switch and dip switch before getting to the bulbs and, back when new, the amperage demand was reasonable. However, over the years, a number of lighting power increases have been made (no LEDs) that I have not been comfortable passing through my aging thin wiring or components. As a result, I added relays to lessen power flow through my components and harnesses while providing more than sufficient margin to handle the increased power draw.

Chet,

Although a separate activation/deactivation switch should be installed to turn on the Driving lights manually, the Driving lights are required to only go on in conjunction with High beams. This Stat Law requirement is reasonable as Driving lights provide a distant narrow beam and are best used in conjunction with High beams provide a wide light. With the detection of oncoming traffic, you want to be able to turn both off simultaneously and not have to react to each independently (which most likely always happen).

Ray(64BJ8P1)
 

Keoke

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Well Ray:
What you pose to do when high beams fail?

with independent switches you can satisfy the law and get home when your headlights fail cuz you are not supose to drive without lights ???
 

steveg

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Well Ray:
What you pose to do when high beams fail?

with independent switches you can satisfy the law and get home when your headlights fail cuz you are not supose to drive without lights ???

I had exactly this happen when I first rewired with relays. I had 10A fuses each on my low and high beam H4 Hellas and 15A on Moss 48W driving lights. 10A was insufficient and the low beams went out in the early morning dark and I drove with only the driving lights until sunup. Now they all have 15A fuses. I usually drive with my driving lights on in the daytime to help other drivers see me.
 

steveg

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Another place to stash relays: inside a gutted voltage regulator. I used this before I moved all my relays to a Buss relay & fuse block on the plenum. Now I use it to cover wiring pass-throughs in the firewall.

screenshot.1790.jpg
 

RAC68

Darth Vader
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Keoke,

That is true but there are a number of failures that will put your Healey out of action and if an emergency, I could physically intervene and jumper the Driving lights as a temporary measure. It would not be difficult to implement a switch between relays to allow power to be directed to the driving lights independent of the High beams. However, under normal conditions you still want the to conform to the law and have your Driving lights turn off when dipping your High beams.

My implementation conforms to the law and, luckily, I have not had a lighting failure. So, what do you want to place your implementation on, the prescription of law with the convenience of responding to oncoming traffic with a single action, or the possibility of a component failure (or, in Steve's example, a miscalculation). My choice, I would rather not provoke receiving a ticket or cause an accident when dipping my headlights but forgetting to turn off my driving lights to oncoming traffic (a expected repetitious task). There is a reason the Law was passed and it will now be Chet's decision to make.

Ray(64BJ8P1)
 
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