Installing an up to date leviton how do i know which wire crosses over to the next? 30A

Youtube has a few videos...

How to wire a 3 way switch: http://youtu.be/7smZbyBSVTg

and Google.com has a lot of pictures and info....

https://www.google.com/search?site=&source=hp&ei=xtUCVaOcFsX2yQTioIKYDA&q=wiring+instructions+leviton+6643&oq=wiring+instructions+leviton+6643&gs_l=mobile-gws-hp.3...5273.5273.0.6545.3.2.1.0.0.0.137.137.0j1.1.0.msedr...0...1c..62.mobile-gws-hp..2.1.117.3.3RsINGRP7ak#q=how+to+wire+a+three+way+switch

for the most part it's a simple system, that requires three wires, one Hot or Common wire, and two traveler wires,
On one end of the three way the common is the light or wire that goes to the light, two travelers to the next three way switch that usually has power as the common wire... hope this helps?
If not contact me, I can walk you threw the process... thanks

Here's the wiring instructions: http://www.leviton.com/OA_HTML/ibcGetAttachment.jsp?cItemId=nNBKTVaZ2nU2mhkps672vw&label=IBE&appName=IBE&LEVCOMP_pses=ZGFA29E0DBC9686AA1D14C9C2AA2763721F62C7F83E969AD4822D897CE157A46A78B7EB01F8BC392D4241779B1759B01270DF9EBAAD8B4427C&minisite=10251

Copy following link for instructions wiring single-pole timer.
http://waterheatertimer.org/How-to-wire-timers.html
http://waterheatertimer.org/Countdown-timer-horsepower-ratings.html

Leviton countdown timer model number is unknown.
Which timer has green lights? I thought the leds were red.
Add comment with wire colors on timer and fuller description of timer, and what the timer does.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

with a three way switch like this, you will have two traveller wires and a common wire. Look in the instructions for the switch or on the back of the device itself to see if there is a wire labeled "common" or "com". This common wire from the old switch hooks up to the common wire on the new switch. I did a bit of searching on the leviton 6602, but couldn't find anything specifically about the three way version (I would venture to guess, however, that the red wire on the old switch is the common). The common on one of the three way switches will always be a constant hot (or power) wire...the common on the other three way switch will be the "switch leg" or the wire that connects directly to the light. The two travellers go to the other two wires. Check the pamplet that came with the lutron device, it should show which wire is common and which are travellers.

What's the problem? You can get instructions at leviton website but also suggest you read competing products manuals to build perspective. These are difficult to install in 3 way wiring situations. In 3-way they only seem to work well when wired to load not line side. In 3 way I suggest you wire in 2. There is a certain way of doing this. I just looked at instructions for Leviton's competition.

The Leviton IP106 Illumatech dimmer switch must be installed at the switch location where the hot feed exists. From your description your hot feed is at the regular 3-way switch location. Swap locations.

Review old switches:
Two old switches > each has 2 wires
Old switch 1 > Red and White
Old switch 2 > Black and White
The same white wire connects to both switches, so effectively they count as 1 wire
This means you have 3 wires ... 1 White, 1 Red, 1 Black
Each switch controls a separate load (light, fan, motor)

New Leviton double-rocker switch:
-Leviton has 2 Brass-colored screws on one side, and these screws are connected together by a brass plate >> your Hot wire will connect to brass screw
-Leviton has 2 Silver-colored screws on other side, and neither of these screws are connected in any way >> the wires going to each load will connect on a different screw on this side of switch.

Hot wire: Each box in your house has exactly 1 hot wire that is connected back to breaker box. This is true for all boxes (excluding boxes that have a 3-way & 4-way switches).
We need to identify Hot wire.

-By code the Hot wire is black for identification purposes ... but your box sounds like maybe the Hot wire is White.
-If your Hot wire is white, that is NOT an immediate safety issue ... it will not cause a fire or malfunction ... it is a code violation ... because code requires things be uniform so next electrician knows what previous guy did. So some day, electrician working outside grabs wrong color wire, and wow. I say this so you know.

Moving on.

Identify Hot wire:
-Pull 3 wires up so they can be tested
-Turn on power
-Use ordinary tester, or old lamp with plug cut off and wires stripped back
-Tape tester lead to sticks so hands are away from voltage
-Power is on. Don't stand in water or touch metal pipes, and you're fine.
-You have 3 wires in box + ground wire
-Test all 3 wires to bare ground wire >> when tester lights up, that is Hot wire ... testing is complete

Connect wires to Leviton double-rocker:
-Power is OFF.
-You have 3 wires - 1 White, 1 Black, 1 Red >> one is Hot wire, the other two wires go to load
-Hot wire connects to Brass-colored screws on new Leviton.
-Brass colored screws are connected together by a brass plate so the Hot does not need to connect to both brass screws.
-The other two wires connect to Silver screws on other side of new Leviton switch
-One wire goes to each silver screw
-Connect bare ground wire to green screw.
-Push wires back into box. Use eraser end of pencil if needed.
-Make sure ground wire is back and away from screws on switch
-That's it.

For this combo , the white wires connect to the two silver screws on one side of the combo .The black power wire connects to the screw next to the switch. IF you want to have the receptacle hot all the time then jumper the hot black from the switch screw to the receptacle screw. The screw in the center is for the black wire from any lihghts that you want to control. IF it is the receptacle that you wish to control with this switch .. then the power connects to the screw next to the switch and the center screw jump a wire to the screw next to the receptacle

Here's a web page that shows you the color arrangement for a crossover:
http://www.littlewhitedog.com/content-8.html
The same info will apply to jacks.
Also, adapters are available to do the crossover for you, no need for wiring:
http://kb.wisc.edu/showroom/page.php?id=3095

power coming in from the breaker box: black wire will go to line-hot screw, and the white wire will go to the line-white screw. the switch wires coming out of the back of the gfci- 1 will go to the load-hot screw & the other black wire will wire nut to the black wire going to the light. the white wire going to the light must go to the load-white screw.