Novice Ancillaries Wiring Question

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Nikki&Austin
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Novice Ancillaries Wiring Question

Post by Nikki&Austin »

We have bought one of these fuse boxes (x10 fuses) to hopefully simplify the wiring of electric fan, fog/driving lights, radio etc.

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As we understand it, this allows us to take just one power feed from the ctrl box and not have lots of in-line fuses into the battery / ctrl box - potentially 2 each for every ancillary / lamp.

Do we assume that we take a feed for each ancillary from whichever relevant fuse we choose and that that simply replaces the power feed to the battery in the following fan diagrams?

For a fan on manual control only, it looks like we splice the wires from the relay together for 86 and 30 to the same fuse/feed, or do they need separate fused feeds ?

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Also, for lamps with non-illuminated switches, i.e., simple toggle 2 way switches it seems less simples ?

We assume that on the relay……..

87 goes to the respective lamp
86 goes to ground
30 would go to the fuse feed
85 goes to the switch
the other connection on the switch goes to ground ?

.....but - does the switch also need to get feed (if the switch is not illuminated) , or does this come via the relay ? If not, is it assumed the switch doesnt need to be earthed as the relay does this ???????? (the switches are in a fibreglass pos - not the metal dash.

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Otherwise, on the following diagram, every lamp would require 2 connections to the fuse box, one for the switch and one for the relay ????????

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Duncan
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Re: Novice Ancillaries Wiring Question

Post by Duncan »

love the ejector seat option! :clapping:

I'll have a think about what you're asking about the fan wiring, in the meantime, I've thrown together a diagram for the lights. The important bit is that the relay connection numbering is correct...
Headlight relay.jpg
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Basicly you're using the switch to enable/disable power to the coil on the relay, and letting the relay do the same for the lights.
Big Daddy
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Re: Novice Ancillaries Wiring Question

Post by Big Daddy »

Duncan wrote:Basicly you're using the switch to enable/disable power to the coil on the relay, and letting the relay do the same for the lights.
But you didn't explain why the relay is necessary Duncan, so:

Relay coil demands very little current so electrical load across the switch is low. Lights require high current which is probably beyond load capacity of the switch, which would would burn out if it was used to switch them without a relay.

However high current switches are readily available these days. So you may find one which will handle current draw of those lights without resorting to fitting a relay in the circuit. Do you know current rating (ie amps) of your lights :?: .. :wave:
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Big Daddy
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Re: Novice Ancillaries Wiring Question

Post by Big Daddy »

Found this 25 amp toggle switch from Halfords. Would be very surprised if either your auxiliary lamps or cooling fan pass anything approaching 25 amps, which means the relays can be eliminated.

That's unless you are triggering cooling fan from a engine temperature sensor in parallel to manual switch, when the relay should be retained. Temperature sensors will only flow a few amps. I recommend installing one, otherwise forgetting to turn the fan on is simply too easy.

Can you advise maximum current (ie amps) for auxiliary lamps and cooling fan please :?: ... :wave:

http://www.halfords.com/workshop-tools/ ... amp-hef355
25amp switch.jpg
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Duncan
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Re: Novice Ancillaries Wiring Question

Post by Duncan »

Big Daddy's on to it...

Only thing I would add, is that with using a relay, you can have the relay in the engine bay and you don't need to run full-ampage (i.e. thick) cabling into the dash to the switch.
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Re: Novice Ancillaries Wiring Question

Post by Big Daddy »

Duncan wrote:Only thing I would add, is that with using a relay, you can have the relay in the engine bay and you don't need to run full-ampage (i.e. thick) cabling into the dash to the switch.
:iagree: But cable size needed for extra lamps and cooling fan is not very thick anyway... :whistle:

Back in 1970s, Jaguar went further by powering components directly from live feed and only switching the earth side of circuits within the passenger compartment. So any severing or chaffing of cables at the bulkhead or inside the car switched components on at zero volts (grounded) but could not cause a fire. Almost doubled wiring required and cost a fortune, but these were Leyland days. And that's without the banks of 6RA relays from Joe Lucas... :rol:
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Nikki&Austin
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Re: Novice Ancillaries Wiring Question

Post by Nikki&Austin »

Thanks for the schematic Duncan, v helpful.

Checked our switches - 16amp apparently. As we have the relays, we might as well use them, although the challenge seems to be finding a place to discreetly mount everything ! As well as fuse boards, someone should have invented relay boards !!
Big Daddy
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Re: Novice Ancillaries Wiring Question

Post by Big Daddy »

Nikki&Austin wrote:As we have the relays, we might as well use them...
Each to their own... :whistle:
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gazza82
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Re: Novice Ancillaries Wiring Question

Post by gazza82 »

"If you're driving on the edge ... you're leaving too much room!"

Club WebEditor.

Cars: "Project 757" '59 A35 2-door bought in 1971 & Subaru BRZ SE LUX Auto plus "family fleet": Alfa MiTo, Peugeot 206, (Ex '98 Alfa Romeo 156 2.0 TS)
Big Daddy
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Re: Novice Ancillaries Wiring Question

Post by Big Daddy »

... :whistle:
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SteveClem
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Re: Novice Ancillaries Wiring Question

Post by SteveClem »

I like these old cars because they are simple and I've been striving for years to make them simpler. Don't think it can be done...
Big Daddy
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Re: Novice Ancillaries Wiring Question

Post by Big Daddy »

:iagree: Austin even resisted fitting a solenoid (alias relay) to the starter motor circuit... :thumbs:
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gazza82
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Re: Novice Ancillaries Wiring Question

Post by gazza82 »

Then I made mine complicated by copying a Mini starter circuit 8-} :lol:
"If you're driving on the edge ... you're leaving too much room!"

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Cars: "Project 757" '59 A35 2-door bought in 1971 & Subaru BRZ SE LUX Auto plus "family fleet": Alfa MiTo, Peugeot 206, (Ex '98 Alfa Romeo 156 2.0 TS)
Big Daddy
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Re: Novice Ancillaries Wiring Question

Post by Big Daddy »

gazza82 wrote:Then I made mine complicated by copying a Mini starter circuit 8-} :lol:
More electrical connections, more switch contacts, more cables, more failure modes just waiting to cause havoc... :whistle:
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Big Daddy
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Re: Novice Ancillaries Wiring Question

Post by Big Daddy »

gazza82 wrote:Then I made mine complicated by copying a Mini starter circuit 8-} :lol:
Original Mini had a mechanical starter switch without solenoid (aka relay). Exposed underfloor location was probably less than ideal (carp)... :whistle:
17H5260_classic_minmini_floor_mount_starter_switch.jpg
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