Strobe wires - separate from others?

[Fearless]

Do the strobe wires need to be ran separately from the other wires in the plane such as landing lights,position lights, servos, etc? I have the CreativAir system for the strobes, landing and position lights for the wings I'm currently building. I have the Whelen strobe/tail positiion light for the aft portion of the plane. I have the conduit from vans to use to run the wires through the ribs in the wings. The wire in the kit is the shielded 18 ga 3 conductor type for the strobes. The strobe power supply is the AVI-PAK brand. I was told that the strobe wire needs to be ran separate from the other wires.

What is the general consensus on this? If it needs to be separate than how far away? The reason I ask is because I would need to make the appropriate holes in the ribs to run the wire through and now would be that time.

As usual thanks in advance for replies

[gmcjetpilot]

The strobe wires are shielded, it should not matter.

[tinman]

You don't need to worry about running the strobe wires next to "low-tech" loads such as lights. There are occasional issues with signal-level wires such as servos. I've never heard directly from anyone who has actually had this problem, so it could be another OWT. My guess is that the shielding in the wires keeps the devils trapped so that they can't get out and play :-)
Don

[Jekyll]

I discussed this topic specifically with TruTrak to determine if I should run servo wires serarately from the strobe wires. They said no difficulties would be encountered and to run everything through the same conduit.

Jekyll

[Mike S]

My -10 has the AHRS and magnetometers mounted in the tail cone, as well as the strobe power supply. As the strobe wiring must go forward to the wings, and the AHRS/magnetometer wires must come back toward the tail, the wires must be running parallel for about 5'.


GRT advises to separate the wires at least 10 or more inches, more is better.

I chose to run the strobe wires up the left side of the fuse, and the GRT wires on the right. I am feeding the right wing strobe wire across the fuse at the spar, which will make it cross the GRT wires at 90 degrees.

The folks at GRT say that the problem of cross talk in wiring is not a problem when wires cross paths, just when parallel.

If you have a strobe system with the power packs out in the wing tips, the problem is eliminated, the single central power pack is where the problem stems from.

Mike

[jdeas]

This is as much of a question as an answer.
The two ways crosstalk and interference happens is emission and induction.
Short of physical seperation, isolating the ground and returning it in the same twisted pair cable reduces both emissions and induction. By sending and returning current spikes in the same twisted pair you can reduce or eliminate these problems.
This action is not needed for any steady state current (lights etc) but is prudent for items with fast and large changes in their current requirments (strobes).

Now the question.
Considering weight and strobe configuration. What is the most common way to wire the strobe? Do people return the current down the same sheilded cable or do they just place it as far as practical from other cables and hope the ground sheild is enough (BTW that shield should only be tied on one end if the cable not both!)

[avi8tor50]

I recently purchased shielded strobe wire and was sent same as you, 3 conductor 18 g. Trouble is, if you're running wires out to the wings from the high power strobe source, I believe you need 16 g. Please correct me if I am wrong. Would appreciate a source of 3 conductor 16 g shielded wire.

[gmcjetpilot]

Originally Posted by avi8tor50

I recently purchased shielded strobe wire and was sent same as you, 3 conductor 18 g. Trouble is, if you're running wires out to the wings from the high power strobe source, I believe you need 16 g. Please correct me if I am wrong. Would appreciate a source of 3 conductor 16 g shielded wire.

Why? Home building is about learning, so its a good question, but think about this, this is what the strobe manufactures and plane manufactures use to route power to strobes in wings and tails of GA plane for decades. With that said Whelen sells 16 ga wire cables, at least today.

Its VERY high volts, not current**. Are you worried about loss (voltage drop)? You are not running continuous high current. 18 g is plenty for an intermittent (hi-volt) service. Its just a fraction of a second on and seconds off, so heat is not an issue.

Also the wire run lengths (20-30 feet) are fairly short, so volt loss is small. Why re-invent the wheel? Just use what they sell you. You are right however, you would have less loss with the larger wire. However the affect on the light output will not be significant, unless you are running long wires.

** The electric company's "grid" starts out typically at 110kV to 220kV (220,000 volts) and drop down several times to 33 kV to 115 kV, than before your house drops to (3.3 to 25 kV). Finally, at point of use, energy is transformed to low voltage (100 to 600 V), varying by country and customer requirements. Why HIGH volts? Less loss. That is why larger aircraft use 28 volt or even a 46 volt DC electrical systems, they are more efficient. In larger jets they actually use AC with voltages up to 400 volts, which is even more efficient. However there are much longer wire runs and demand on a Boeing 747.

For power: voltage times current. That's why: W(att) = V(olt) x A(ampere)

If the current is doubled, the energy loss quadruples. So if you need 1000 watts power its more efficient to send 1000 volts at 1 amp than 1000 amps at 1 volt.

I don't know what the Volts are coming out of the power supply, but the power in is about 75-150 watts (@ 12 volts)! So if it steps up volts there would be a nasty shock coming. It also depends on flash rate. They rate the energy out as Joules which is: Joules = watts x seconds, therefore watts = joules/seconds.

Some things like starters NEED current and lots of it. Your starter NEEDS something like 2 awg. Why? Its VERY high current (up to/over 300 amps @ 12 volts) and it's continuous, at least for short periods. However lets say you wanted to run 300 amps continuously, you would have an even larger cable by several sizes, like OOO or OOOO gage (about 7/16" diameter wire + insulation). That is why you should not crank your engine continuously or for several long cranks without cool down time between. The starter windings get even hotter. Follow the manufactures DUTY times carefully. What if you use 4 awg? Well the wire will just get hotter and you will have more loss (voltage drop). Heat is the lost electrical energy turned into heat and not work.

Home building and plane design in general are always a series of compromises. You can always go to higher gauge wires, but the plane has to fly and weight and cost go into the design parameters. Usually wire gage is based on voltage drop and/or temp rise for a given service requirement (volts/current/duration). Than the installation, length of wire run and if its bundled with other wires (large thumb sized assemblies not a few wires together) factors in. Finally there is MIN gage (for durability and ease of installation).

[az_gila]

Originally Posted by avi8tor50

I recently purchased shielded strobe wire and was sent same as you, 3 conductor 18 g. Trouble is, if you're running wires out to the wings from the high power strobe source, I believe you need 16 g. Please correct me if I am wrong. Would appreciate a source of 3 conductor 16 g shielded wire.

All of the Whelen cables are 16g .... per their catalog (page 5)...

http://www.whelen.com/pb/Aviation/An...ice_Manual.pdf

Did you buy someone else's cable?

UPDATE

AeroFlash says to use 18g cable... agreeing with George above...

http://www.aeroflash.com/aeroflash_faqs.php

Just go for it with the 18g cable... good shielding is probably more important than the gauge...

gil in Tucson

[gmcjetpilot]

Well I called Whelen. Interesting, the voltage from power supply to flashtube is 200 volts and little current, but what is interesting is there is a transformer that steps up to 7,000 volts right at the flash tube! That click you hear is the transformer (electronics). I did not know that, as Johnny Carson would say to Ed Mcmahon.

Gage wise, Whelen does sell 16 ga, Aeroflash sells 18 ga (thanks gil, good to know). Whelen says they use other gages (in other applications) from 14 ga to 18 ga. For example in other than aviation applications, you might have a cable with 10 strobe lines in one, so they use smaller gages to keep size down. Bottom line, if you are less than 60 feet, either 16 ga or 18 ga is plenty, for the reason mentioned, high volts (200 v) and low current. The KEY as Gol says is the insulation and shielding.


News FLASH!

-Whelen, in about a month or so, will have 14 volt LED nav lights that go into the standard A650P#14 nav/strobe light head. Yea.

-LED Strobes? Yes they have now but not in 14 volts and not in a small package. There is no plan right now to have a small 14 volt powered wing tip LED strobe.

-They are also about to release a LED landing light, but think its 28 volts?