Lights added.

hazmat · Dec 5, 2002

Wouldn't the fuse burn out in the panel before it fryed any of the wiring harness?

Besides small wire/big fuse; There are more possibilities for fryed wiring harnesses. The fuse should be located at the power source, if the fuse is "downstream" and the wire shorts ahead of it, the fuse will offer no protection.

Most distribution panel systems have a large main fuze located at the battery with a large guage wire running to a bus on the panel. The fuzes at the panel connect directly to this bus and therefore protect the entire run of the wiring harness.

Another possibility is occasionally when multi circuit (pin) connectors are used there is a chance to put a wire in the wrong pin connection. you could inadvertantly be connecting a small wire to a large wire & large fuse.

Anonymous Poster · Dec 5, 2002

Dang it Hazmat - I was all prepared to write at least a page explaining that same things you did in a few short paragraphs /w3tcompact/icons/smile.gif

Well said!

Gary_in_Indiana · Dec 5, 2002

"Where did you find the lights with a switch in the housing?"

Actually, I can't take credit for that. Spencer showed those in a post he did on his lights. He said he got his from his New Holland dealer for $26 each. They are made by the J.W. Speaker Corporation and sold as "Agri-Brite," I believe.

In talking with them on another matter I asked about those lights and was told the cost from a distrubutor was over $28 each so buying through New Holland (which buys direct from Speaker by the boxcar) sure sounds like the way to go if you want those.

Again, let me say he recommended against those for a tractor and instead recommended the round, rubber housed lights. That having been said, I still like the 4x6 holgens with the switch. /w3tcompact/icons/smile.gif

What I really like are the HID (high intensity discharge) lights they make. They give off a true daylight lighting four to five time brighter than halogens and last 4,000-5,000 hours with no filament to break or become damaged.

They sure sounded like the perfect light. The only problem is the price. They retail at about $500 each!!! /w3tcompact/icons/shocked.gif

When he told me that the next words out of my mouth were, "So, what about halogens..." /w3tcompact/icons/laugh.gif/w3tcompact/icons/laugh.gif/w3tcompact/icons/laugh.gif

Gary_in_Indiana · Dec 5, 2002

"How tall and wide is your 4200 ROPS?"

I have no idea without either looking at a spec sheet or measuring it. I do have the folding ROPS, which is higher than the standard.

I'm working on another custom modification, too. One thing I'm in the process of doing is raising the seat base a bit to allow more legroom. I'm also moving it back from the dash and steering wheel a bit and adding a swivel option. When I'm done, I'll operate the tractor with the seat all the way forward on it's tracks. I'll slide the seat all the way to the rear of the tracks and swivel it around 180 degrees to operate my backhoe. I'll eliminate the existing backhoe seat altogether.

If I get all this done and it works I'll post some pictures here for everyone. Wish me luck. /w3tcompact/icons/smile.gif

Anonymous Poster · Dec 5, 2002

Hi,

You should use a relay for safety's sake rather than run the amperage for the lights thru the toggle switch. 

I doubt there is any safety consideration at all at the 12 volt level.

A relay in my humble opinion just complicates the circuit, providing that the toggle switches that are used are rated for the voltage and current levels that are being switched on and off.

What protection would a relay offer if it is added to the circuit? If a wire should short out, the relay will not save anything, it will be the fuse that is also in the circuit that opens and protects the wiring. Same action that will happen if the relay is not in the circuit at all.

Most important thing is to fuse the circuit properly. That would be sizing the fuse slightly higher than the expected current draw. But even if you are five amps above the expected current draw, that is in the practical world no big deal. 5 amps @ 12 volts is 60 watts. Not likely to cause much damage in wiring mounted externally, like would be the case on aux lighting on the ROPS.

Sorry to sound so contrary, but I just don't think the complication a relay adds to the circuit on the tractor adds any real benefit at all. And should you want to control four lights independently, the logic would dictate that you need to install four relays...not something I want to do.

There are many applications where a relay is used for safety purposes, for example, controlling a higher voltage circuit. A common example is a motor control circuits where 480 volts is controlled by 110 volts. There are many others.

Put a relay in the circuit if you want to. To each his own. But I don't think anyone should feel that it adds any safety advantage.

Buy the way, amperes are not the danger, voltage is. It is the voltage that drives the amps through your body to kill you. 12 volts is not enough to do it. A shorted battery is very dangerous...can burn you bad...but it will not electrocute you. Just won't happen.

I hope these words don't come across too boldly, as I don't want them too.

Just another opinion [backed by some experience] that can be considered by anyone interested.../w3tcompact/icons/smile.gif

Bill in Pgh, PA

Anonymous Poster · Dec 6, 2002

Bill, I would have to respectfully disagree with you regarding the need for relays at the 12v level. There is quite enough amperage draw from some accessories to cause overheating or meltdown from a component that is not rated for that amperage draw. I would also say that it's the amperage that can harm you - if I grab the battery cables with the engine running or off, there is very little amperage draw to smack me, but if I grab the cables while starting the car, it's a different story. The 12 volts would not have not changed - the amperage draw did.

In many cases, the switch that is used may be rated for 12v, but it may only be rated for 5 amps. If you've got lights that are drawing more than that, the switch becomes a point of resistance in the system. Resistance equals heat and the possibility of failure.

The relay is not installed to protect the entire system - that's what the circuit breaker and/or fuse is for. The relay is installed to allow full voltage feed from 12v source to the load without having to route that full voltage and amperage draw through the switch as well as the resultant additional heavier gauge wiring that would be needed.

Case in point - on many of the older cars/trucks, the 12v feed to the headlights is routed straight through the headlight switch (no relay). This works, but is very marginal, as evidenced by those who have installed anything more than the standard T3 or equivalant hi/lo sealed beam. Installing any type of higher wattage halogen light, etc, often causes the headlight switch to overheat and fail. What I typically do in this case is install relays for hi and low beams, allowing the switch to simply control the relays. Headlight feed does not go through the switch anymore, just through the relay. The relays are protected with auto reset circuit breakers - if there is a problem, then the breaker will trip, then re-connect when it cools down. This is exactly what the newer cars have gone to.

You don't have to install 4 relays for 4 lights, even controlled independently if you use a diode from each of the switches to the relay. This will not allow voltage to backfeed from the light that is on back to the other lights.

I agree that it may sound more involved to do all this rather than route a piece of wire from the battery to a switch to a light. However, in my case, I have to deal with some expensive toys and I have to get it bulletproof from the beginning.

Anyway, I do appreciate what you have to say - I don't think it sounds contrary at all, just an alternate view. Thanks.

MikePA · Dec 6, 2002

Chevdog, I wondered about this as well. If relays weren't needed why would almost every aftermarket set of lights, e.g., KC HiLites, include a relay? I'm not an EE, I just install what comes in the package figuring the manufacturer knows (should know? /w3tcompact/icons/tongue.gif) what they're doing.

hazmat · Dec 6, 2002

Chevdog, I wondered about this as well. If relays weren't needed why would almost every aftermarket set of lights, e.g., KC HiLites, include a relay?

The main reason that relays are used in automotive (12V) systems is to keep the wire size small for routing into the dashboard. The added safety is a bonus. Few things (Starter motor excluded) draw enough current to be dangerours.

You can also make a rudimentary "computer" out of relays that will do simple logic functions. IE: If the door is open or the button on the dash is pushed, turn the dome light on.

The logic can be accomplished with switches, but then you'd have to run the wires everywhere, instead of from a switch panel to a central relay location. Just think how many gadgets only work when the ignition is "hot". Thats alot of wires to run thru the steering column. The relays make creating a wiring harness a manageable task instead of a rats nest of wires criss crossing around the vehicle.

kyoders · Dec 6, 2002

Chevdog,

I think Bill is right. The current you would draw by grabbing the battery terminals is a function of the voltage between the terminals and the resistance of your body. It does not matter what other devices attached to the battery are drawing at the time (actaully, it does matter, but not in any way meaningful to this discusion).

To check this (without endangering yourself), attach a 12V light with an inline fuse to the battery terminals with the engine off. The light will draw some current based on the resistance the light circuit presents to the battery potential. This is going to be some relatively small current, say about 5 amps for a 60 watt light, so make the fuse about 7 amps or so.

Now go start the engine, which is going to pull a lot more current from the battery. If you are correct, the light circuit would see this current as well, and the 7 amp fuse should blow. Obviously, this won't happen, or every fuse in the car would blow every time you started the engine.

If you were to connect the light in series between the battery and the starter circuit, then you are going to pull all that current through the light, and I would expect the fuse to blow. You would also be altering the effective resistance of the starter circuit, which would have other consequences. If the light circuit could deal with the current, you would actually be lowering the current that would be drawn through the starter.

The only difference between your body and the light circuit is the resistance presented to the battery terminals. The human body, in most situations, is a pretty poor conductor/high resistance. By Ohm's law, that means it takes a much higher voltage difference to produce a 1milliamp current through the body than it does through a light bulb of mucher lower resistance.

As an interesting note, one of my EE profs stated that it only takes 15 milliamps passing through your heart to kill you. That's .015 amps. It's one of the few things I remember from back then

Kevin

Anonymous Poster · Dec 6, 2002

Hi Nick and all,

Just as a follow up...

I would have to respectfully disagree with you regarding the need for relays at the 12v level. There is quite enough amperage draw from some accessories to cause overheating or meltdown from a component that is not rated for that amperage draw.

Certainly true. But that is why circuits are fused...hopefully. IF the circuit is jproperly protected by a fuse, the fuse will open under the overload condition and the huge amount of heat that might be generated by the hundreds of amps the battery can supply then becomes a non-issue.

I would also say that it's the amperage that can harm you - if I grab the battery cables with the engine running or off, there is very little amperage draw to smack me, but if I grab the cables while starting the car, it's a different story. The 12 volts would not have not changed - the amperage draw did.

The only danger the amps at the 12 VDC level pose to any of us is the burn danger, or perhaps if there are enough of them flowing [won't happen in our tractor/auto world] to generate a strong enough magnetic field to pull magnetic objects into the air as projectiles.

Accidently short out your battery terminals with a wrench and you will see some heat generated! Forgotten oxygen cylinders left in MRI rooms in hospitals have done bad things when the MRI was activated and they were suddenly attracted to it!

I hesitated to post this follow up because it may sound argumentative [gee...if I could only spell!] but here goes anyway.

As was mentioned above, it takes very little current to harm a person, but it does take more than 12 VDC drive that current through the human body in most cases. Maybe in all cases...But this is not the issue we are addressing anyway, I don't think. It was more protection to the tractor if things go wrong in the wiring we install.

And I think it gets down to one thing. Relay, switches, wiring, whatever we install...if it is not protected by something that will interrupt the current supplied by the battery, when something goes wrong, there will be smoke and a certain amount of fire!

It is the fuse/circiut breaker that offers this protection. NOT any of the installed components. [I have seen wires themselves burn open and act like a fuse though, so never say never, right? /w3tcompact/icons/smile.gif]

Have fun tractoring!

Bill in Pgh, PA