LED Ring Light

[Jeff Pahl]

Originally Posted by tomy

srry for sounding stupid but our electrical mentor will not be here tonight

so we need 12 gauge wire then?

based on this

http://www.134team.org/docs/frcManual/GameRobot4.pdf

Originally Posted by MCahoon

The real decision is made by the robot inspector at a regional,....

Which very possibly will be me...

Refer to <R44> on page 24 of the document you linked to (and you probably want to start referring to a copy from the usfirst.org server to make sure you are always using an up to date copy) if the ring light is connected to a 20A breaker on the power distribution board, then it can be connected with 18AWG wiring.

Run the 18AWG wire up to a point close to the light, and then splice to the wires that are part of the light. Make sure you use a mechanically robust connection, such as a crimp butt splice, soldering, or the terminal strip from the KOP (which you can cut down for just the number of terminals you need).

[Mr V]

Originally Posted by Jeff Pahl

Make sure you use a mechanically robust connection, such as a crimp butt splice

In the world of vehicle electronics crimp butt connectors are not considered robust. By reputable automotive electricians they are often referred to as emergency or temporary connectors or guaranteed failure points. For those that masquerade as "professional" technicians that use them they are referred to as job security.

The best ways in my opinion, to join the gauge of wire that normally is attached to the ring LEDs to the 18 ga wire would be to:

A. Solder them and cover them with adhesive lined heat shrink.

B. If you don't want to solder is to use a un-insulated parallel crimp connector and cover it with adhesive lined heat shrink. Even then I'd suggest soldering.

Those 2 methods meet the OEM level conditions for joining wire of different gauges or a splice of wire of the same gauges for either Ford, GM, Chrysler, Navistar (International) or Paccar (Kenworth and Peterbilt) depending on who's service literature you consult (with the solder in the second method).

[Jeff Pahl]

Originally Posted by Mr V

In the world of vehicle electronics crimp butt connectors are not considered robust. By reputable automotive electricians they are often referred to as emergency or temporary connectors or guaranteed failure points. For those that masquerade as "professional" technicians that use them they are referred to as job security.

Properly sized and installed crimp butt connectors are considered robust enough by NASA for use on spacecraft (per NASA-STD-8379.4). In fact, they are even acceptable with multiple wires entering one end of the splice. As always, the important thing to remember is "properly sized and installed".

My number one preference is always a properly done soldered splice connection, with heat shrink. Again, the important thing is "properly done", which means some sort of mechanical joint between the two wires prior to soldering, such as a hook splice or Western Union splice. Proper wire tinning. Solder not wicked up under the insulation.

What I was trying to get across in my original posting was that approaches like just electrical taping the two wires together are not "mechanically robust".

One of the biggest things to watch out for in any wire splice is to not damage the conductors when stripping the wires. It doesn't matter how good the splice is if the wire breaks off in your first match. And when it breaks inside the heat shrink tubing you applied over the splice (or inside the big sticky gooey wad of electrical tape you had someone gob over the connection when you were done), the wire won't necessarily fall off and be obvious why your light (or whatever) is not working. Or works intermittently.

[DonRotolo]

Cheap butt splices crimped with a simple pliers-like crimper is about as worthless as Mr. V asserts.

High-grade butt splices exist, and when used with the proper crimper, can exceed the reliability of the original wire, without solder.

It all depends on what you mean by butt splice, eh?

[Mr V]

Originally Posted by Jeff Pahl

Properly sized and installed crimp butt connectors are considered robust enough by NASA for use on spacecraft (per NASA-STD-8379.4). In fact, they are even acceptable with multiple wires entering one end of the splice. As always, the important thing to remember is "properly sized and installed".

Yes but NASA doesn't use the insulated crimp connectors you'll find at your local hardware or auto parts stores and many FIRST Teams do. I should have been more clear that I was referring to those type of crimp butt connectors. Although they exist most people will be unable to locally obtain versions that are properly sized for splicing anything other than 2 wires of the same gauge. Either way the vinyl insulated connectors are next to impossible to determine if they have been properly installed (the "pull" test is not valid and may compromise a connection that was good) and most tools available at the same place that you buy those connectors are not capable of installing them properly. The insulated vinyl connectors are also known for cutting strands of the wire leading to the eventual failure of the wire.

[Sargon2335]

My team is trying to hook up the ring light. I already have a terminal strip in place, but we do not know which side is positive and which is negative. I have looked on andymark, the vendor's website, and many different threads on chief delphi. Do you guys know which wire is which? I was assuming the one that is tinted copper is positive, but I don't want to plug it in until I know for sure.

[Alan Anderson]

Don't worry. It's okay if you connect the LED ring light backwards temporarily while you determine which wire is which. You won't break anything if you put battery voltage across it in the wrong direction.

(It'll break if you put too much voltage across it in reverse, but that would be just as bad for it in the forward direction too.)