what amp for earth wire?

[autolycus]

Lucar has become a bit of a "hoover" word for spade terminals. Have a look at the Autosparks selection, where you'll see that you should really match both connector width (obviously), and the cable size. You can get away with smaller cables in terminals designed for larger ones, but they won't be as neat. You'll also see the various patterns of sleeve that they sell. Once you've carefully crimped a few connectors onto both ends of a length of cable, then discovered you've forgotten to slide the sleeves on first, you'll swear never to make the same mistake again. Till next time.

IMHO, these spade terminals make a far sounder and neater job than the pre-insulated ones you can get. A car with those nasty bits of squashed red, blue, and yellow plastic screams "bodger" to me.

On cable sizing, if in doubt, err on the larger size. Just occasionally, space for a cable or bunch of them, is the limiting factor, but usually it's just a matter of bigger cable costing a few pence more.


Kevin

[JaneHibbert]

interesting... what is the 'normal' common size, for example what size would you use on the back of a standard lucas / morris dash switch?

[JaneHibbert]

hmmnnn... i see they would look nicer on a regulator or something, and maybe more insulation on the back of a switch on the dash etc.

you would use a sleeve on a female one pushing it onto a male regulator spade i think yes? But would you use two sleeves if you were joining two wires together?

[bmcecosse]

You wouldn't use Lucars to join two wires - but you do get piggy-back connections which allow a second wire to couple in. Normal size is 6mm.....

[JaneHibbert]

what would you use to conect two wires, you see i have been using spade conectors

[bmcecosse]

Basically - you don't! Run new cables of the correct length - or piggy-back at a terminal.

[JaneHibbert]

hmn. what about when you put new headlights in and the old wires don't have bullet conectors?

[autolycus]

By far the most common size of spade connector on these cars is 1/4".

Male spade connectors aren't used much at all: offhand, I can only think of one fairly common usage, and that's where the ignition coil has one male and one female connector to avoid mixing up the + and - (or SW and CB) connections.

I think Roy's gone a bit OTT saying you shouldn't join cables, as there are plenty of places this was done, and for good reason. Bullet connectors were the usual factory method at the time, though nowadays the trend is towards multi-pin plugs that are just - better. I find fitting bullets is a PITA, but that's because I haven't got a bullet crimping tool, so I solder them. This is OK-ish with new cable, on the bench, but under the dashboard, with a cable having slightly oxidised, unplated conductors, it's no fun.

Note also that bullet connectors come in "solder" and "crimp" forms, and should be sized to the cable. I've noticed that some recent multiway bullet connectors haven't been well made, and have needed opening up a little before use. Be careful to push the bullet fully home, or they may leave an exposed bare bit. And we mustn't have exposed bare bits, must we.

Kevin

6mm indeed!!! They're British

[bmcecosse]

Well yes - I meant not to join them with Lucars...... if bullets are missing - then solder (or crimp - but it's a poor alternative) new ones to the ends, and carry on as before.

[JaneHibbert]

I have used little insulated blocks with screws in... they seem to work, might try soldered bullets when or if i have to do them again. BMCECOSSE, is there an alternative to 6ra regulators as they seem quite expensive?

[JaneHibbert]

I meant relays!

[autolycus]

"Chocolate blocks", or insulated terminal strips, have their place: but it's not on a car. Especially not if they're hanging in mid-air, supported by their cables, with or without a few turns of insulating tape wrapped round their unhelpful shape. I dislike them even more than I dislike pre-insulated crimped-on connectors. One problem is that they are a vibrating mass, supported by fatigue-prone copper wires which have already been locally stressed by having a screw graunched into them; another is that they are impossible to insulate satisfactorily in the confined space under a dashboard; a third is that once you've removed a cable from them a time or two the cable will need cutting back and stripping again. And they look horrible. For a permanent connection between cables, splice them together, solder them and insulate with heat-shrink, which is truly a wonderful invention.

I'm in favour of crimped bullets, done with a proper bullet ratchet crimper, but these tools are expensive for the odd job. Soldering is more difficult to do well, especially on older cables, and it's all too easy to melt the cable insulation. If you try to crimp bullets with your teeth, or pliers, or your wire cutters, I agree with Roy.

I think you need to be a real purist to insist on RA series relays, especially as they'll be cheap imitations of an originally cheapish product. Autosparks and Vehicle Wiring Products sell most varieties of relay that you could want as generic products at a quarter of the price.

Kevin

[bmcecosse]

The little blocks with screws (choc block) are TERRIBLE - please - don't do that !!! Endless trouble will lie ahead. The 6RA is the best from a historic/classic point of view - but of course there are other relays out there.

[rayofleamington]

Looking at the original post, this thread is a bit concerning. Safety is not really mentioned, and neither is the way to make the size decision.

It should be the same - or greater. Headlamps only need 5 amp wire (to each filament) - but more is better! Where do you read 17.5 ??

That's pretty risky advice without further explanation.
The minor headlight wiring is a single feed which T-s off for both lights via a connection at the rh inner wing.
The running current of each individual headlight is usually well under 5 amps, but inrush current is >5. A 5 amp cable gives no safety protection.
For the headlight feed, you need to consider a headlight feed current of 10 amps - therefore the appropriate wire should be capable of MUCH more. Running a "5A cable to the headlights" would lead to a fire.

Fuses are sized to stop the wire catching fire & fuse sizes are limited (e.g. 10A, 15A, 20A)
So if you want SAFE wiring on your classic, the fuse size should be big enough for the electrical equipment, and the cable should be capable to at least 50% more than the fuse. This includes the supply and ground wire/s - and all other wire/s off the same fuse.

Using appropriate fuses and wire sizes is easy on paper but harder in reality. The wire for sale at the usual outlets/shops may not be available in the sizes & heat ranges that you want. This leads to using a few standard wire sizes and going to the next size UP if/when you don't have exactly what you want.
For ground wires that are multi purpose (e.g. a common ground wire) it needs to be sized for the fuse rating of all items connected, added together.

[bmcecosse]

Don't agree Ray - the headlamps use only 4 amps as you say, and the inrush lasts less than 1 second - so 5 amp cable is more than sufficient to each headlamp. The lighting cables on modern cars are incredibly slim! Yes - the common feed to a split point needs to be double that rating, pretty sure that was not the plan here. The intention here appeared to be to splice off extra lights from the existing - which without use of relay(s) is of course a sure way to cause problems.

[JaneHibbert]

actually in my original case it was the fact that somebody before me had cut wires short which run the last few feet to the headlights. so i needed to add a couple of foot of wire to conect them. so in the end i went for 7.5 amp wires. which by both of your reconing seems safe. the other wiring im slowly working on. but at the moments brakes are the issue

[bmcecosse]

Well - that will be fine. How did the headlamps work then??? But choc-bloc is NOT an acceptable way to do the job.

[JaneHibbert]

they worked because the previous owner had already added wire but it was very thick household type wire which i know wasnt right!

[bmcecosse]

Oh dear......

[tysonn]

If youre still struggling a little with the electrics I don't mind giving you a hand.
Mick