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Ground for Lighting

S

szicree

Well Known Member
I hope this doesn't seem like too stupid a question, but how are most folks grounding their landing/taxi lights? I'm building a day vfr machine, but had installed the leading edge lights way back when and figure I'll wire em up as wig-wags. Up til now all my panel grounds are going to the Nuckolls style ground block, but I'm unsure if it's worth running ground wires all the way through the wings. Hopefully somebody (more than one opinion is nice) will straighten me out.

Also, same question regarding fuel sender.

Thanks everybody.
 
szicree said:
I hope this doesn't seem like too stupid a question, but how are most folks grounding their landing/taxi lights? I'm building a day vfr machine, but had installed the leading edge lights way back when and figure I'll wire em up as wig-wags. Up til now all my panel grounds are going to the Nuckolls style ground block, but I'm unsure if it's worth running ground wires all the way through the wings. Hopefully somebody (more than one opinion is nice) will straighten me out.
Click to expand...

I didn't bother - the landing light is entirely a resistive load (not going to be making EMI) and all my radios etc have a common ground at the firewall anyway. Therefore no way that this ground could screw me up.
 
Little weight.

szicree said:
I hope this doesn't seem like too stupid a question, but how are most folks grounding their landing/taxi lights? I'm building a day vfr machine, but had installed the leading edge lights way back when and figure I'll wire em up as wig-wags. Up til now all my panel grounds are going to the Nuckolls style ground block, but I'm unsure if it's worth running ground wires all the way through the wings. Hopefully somebody (more than one opinion is nice) will straighten me out.

Also, same question regarding fuel sender.

Thanks everybody.
Click to expand...
kevinh, is probably right, but I have individual strobe power supplies in each wing, so they are getting their own ground. There are two other lights, the NAV and Landing Lights. I am debating running one more ground wire out for those two lights.

I was thinking about one big ground for all lights but there is no real savings or increase in efficency. To run the extra ground cost about 3.18 oz. per wing of extra weight.

George
 
Grounding

szicree said:
... how are most folks grounding their landing/taxi lights? ...

Also, same question regarding fuel sender.
Click to expand...
I'm grounding the landing/taxi and position lights locally. I asked Bob about this and he said "no problemo". Not sure what you mean about the fuel sender. Mine has one big screw on it to go to the gauge, and the other end is grounded to the wing automagically. Is this the one you use?

 
No extra ground wire is necessary. Airframe ground is fine for all these applications; nav, landing lights, strobe p/s, fuel gauge senders, etc.
Mel...DAR
 
I ran ground wires

I ran ground wires for each load out on the wingtips: landing light, strobe, nav. I'm just fussy that way...I'm sure it would be fine to use the airframe as ground.
 
szicree said:
Thanks for all the replies. I guess I'll just ground locally and save a little wire. :D
Click to expand...

I ran a ground from the main firewall ground, to a wiring junction box under the seats (RV6A). From there, it tee's about 2 1/2' to each wing's inboard rib.

All lights are then grounded to the wing, but I felt better about running a heated pitot tube ground back to the inboard ground.
 
Survey says? OK now how do ya make a good ground?

Ok drill a hole in the aluminum, put a screw thru it, bolt crimped wire lugs down. How do you keep the connection "GOOD".

Can the aluminum and electrical connector interact and corrode. DO you cover it with some corrosion protection or sealant it?

I wounder what the electrical resistance is between the battery ground and outboard rib or end of the spar is? Any one know?

Pictures? Cheers George
 
Grounding

I agree with Mel...All the extra ground leads produce ground "Loops" and interference with Nav /Sound Equip. One solid ground on the airframe does it.
Billy D
 
If references help, I was an avionics technician in the USAF for 6 years.
Over 40 years in electronics with Texas Instruments.
Airframe ground works fine!
Mel...DAR
 
Testing??

Can the aluminum and electrical connector interact and corrode. DO you cover it with some corrosion protection or sealant it?

Pictures? Cheers George

George, I hope you are only testing us....

The answer to the above is very clearly given to us by the FAA in, what else, AC 43.13-1B.

Table 11.14 on page 80 of this section covers it to the letter.

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99c827db9baac81b86256b4500596c4e/$FILE/Chapter%2011.pdf

The hardware used depends on the materials involved... if the correct hardware is used, then the corrosion problems and dissimilar metal issues are taken care of.

As always, the AC 34.13 is the bible.

gil in Tucson

PS the MIL handbook recommends the same procedures...
 
Mel said:
If references help, I was an avionics technician in the USAF for 6 years.
Over 40 years in electronics with Texas Instruments.
Airframe ground works fine!
Mel...DAR
Click to expand...

Since my 6A spar is anodized, and everything else was two part epoxy primer, neither of which will conduct current on the surface, I ran a ground wire to the inboard rib, since I didn't want to totally depend bolts or rivits making a connection through scratches or un-primed drill holes.

Other than that, the wing lighting and tail light, grounds through the frame, while radios & gauges ground to the main firewall/battery ground
 
Groundy & Loopy

az_gila said:
Can the aluminum and electrical connector interact and corrode. DO you cover it with some corrosion protection or sealant it?

Pictures? Cheers George

George, I hope you are only testing us....

The answer to the above is very clearly given to us by the FAA in, what else, AC 43.13-1B....
Click to expand...
Nope, no test; that is perfect, just what I (WE) needed. I knew I saw it somewhere. My point, people slap metals together in their airframe grounds that are incompatible. Add mosture and current = battery. KEY uses aluminum washers directly adjacent to the structure on each side, and than Cad plated hardware. Cad plated AN hardware is common so that's good. I have seen copper which is worse than steel. Depending on the type of terminal finish Cad only may be needed. Whatever you do, no tinned copper against aluminum structure.

We thank you.
I Thank you George :D

billy d said:
I agree with Mel...All the extra ground leads produce ground "Loops" and interference with Nav /Sound Equip. One solid ground on the airframe does it.
Billy D
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Billy D, ground loops as I understand it has to do more with audio devices, where the phone/mic jack is grounded in one place and the electronics are grounded in another, producing two Gnd paths, thus a GROUND LOOP, for example. It is critical for avoiding audio issues, which should have a SINGLE point ground NOT anywhere on the airframe. That's my story and I am sticking to it. :p

You can ground an item with a dedicated ground wire and not have it also airframe ground. Some items like NAV lights are case ground and harder to isolate from the airframe, but my Nav lights, like everyone's, are in a fiberglass wingtip, so it needs at least a jumper wire to wing structure anyway.


The ground wire/strap from the NEG side of the battery to the engine or firewall might not be so "hot" by the time it gets to the wing tip? It should be groovy, but a good ground strap to the airframe; (may be) also a fuselage to wing strap would be a good idea? Just a thought.

If the main airframe ground strap comes loose it can play heck with your whole electrical system if airframe grounded. When there was an electrical problems, many times it was from poor grounds.

George

Mel said:
If references help, I was an avionics technician in the USAF for 6 years. Over 40 years in electronics with Texas Instruments. Airframe ground works fine! Mel...DAR
Click to expand...
Sufficient overkill in qualifications, :D thanks Mel. You got to love the wealth of knowledge on the VAFNET forum. I hear you but I am scared of airframe grounds for some weird reason? I guess I will have to get over it. Cheers G
 
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Grounding

Mel said:
No extra ground wire is necessary. Airframe ground is fine for all these applications; nav, landing lights, strobe p/s, fuel gauge senders, etc.
Mel...DAR
Click to expand...

If I ground my landing lights, nav lights, strobe lights in each wing to the wing main spar toward the outboard end (pitot heat and AP servo too?), is there a need to run a ground from the fuse to the wing spar roots to assure a solid ground? Thanks!
 
I think somebody is gonna have to check this with a meter, but it seems like with the gazillion bolts holding the wing on that the connection would be made someplace.
 
Erratic Gauges

I was at just about dark yesterday when I turned on the Nav Lights and my Vans oil temp and fuel pressure gauges would peg out. I have seen some minor fluctuations in the past but this was by far the worst.

At the time I had been flying for about an hour or so and it was pretty hot outside as well. Im thinking it has something to do with the ground for the nav lights. The lights are located in the fiberglass tips and have a grounding wire attached to an end rib. Any thoughts? :rolleyes:
 
I grounded my nav/landing lights locally to the outboard rib--drilled a hole, used a fast on on the ground wires, used a star washer to "dig in" to the aluminum. Absolutely no noise in my audio system. I also talked with Bob Nuchols before doing this. Strobes are grounded to the power pac and the a/p servo (located in wing) have ground runs to the fuse.

Good luck,

db
 
Resurrecting an old thread.......

General concensus on this thread was to ground wingtip light units locally to the airframe at the outboard rib.

I will be installing the Duckworks MR16 HID upgrade into my wigtips with an HID ballast mounted on that outboard rib.

Does adding HID ballasts into the equation affect the 'local ground' recommendation?

Thanks in advance...
 
Hi David,
Thanks for your post. I must admit that instinctively I feel it would be prudent to treat the HID ballast as a special case and run a ground wire for it, as you have.

I appreciate that you have done the same for each component at the wingtip but I'm inclined to ground the 'simpler' components, such as the position lights, locally.

Thanks for the reminder. I had previously read that "Wiring for Smart People" doc and picked up a few things. I particularly liked the idea of using colour coded wiring and have followed that piece of advice. Only downside is that it makes deciding what wire quantities to purchase somewhat more complicated!
 
I had one 'gotcha' with using local grounds, and that was my fuel senders. When I hooked up the resistive senders to my BMA engine pod, it didn't work. Since the pod has a ground connection for each tank, I tried connecting that directly to ground and still no luck. An email exchange with Greg Richter revealed that the airframe ground generated too much 'noise' for the pod to reliably sense resistance, so I isolated the senders from common ground and ran a dedicated ground wire from each sender to the pod. Sure enough, it worked. The only reason I mention this is so that someone whose equipment doesn't work even though everything seems hooked up properly might consider if the common ground may be causing their problem. Most of the time, it will be just fine.
 
Good idea to provide a dedicated ground, especially with the HID's. Even with resistive landing lights, it would be a good to use a dedicated ground wire routed as closely as practical with the supply wire to lessen the probability of stray magnetic fields, making the compass and magnetometer(s) happier.

Yes, commercially produced aircraft have used the airframe for an electrical ground return for years as a manufacturing cost saving, and the electrical components themselves aren't affected, but the compass correction cards in some of those airplanes look like they came out of a random number generator.

(BSEE, University of Tennessee, 1979);)
 
It is best as much as possible to use twisted pairs when routing the wires. I would not do it any other way for strobe and HID power feeds.
 
Thanks for that, Dan,

Regarding the "as much as possible", how far do you go?.......

I take the twisted pair from the HID ballast back to the switch.

Does the ground wire part company with the +ve there at the switch?

Or do you recommend skipping the ground wire around the switch and continuing the twisted pair to the breaker on the busbar?

I.e. How critical is twisted pair wiring on that breaker-to-switch wire section?
 
Dan Blumel said:
It is best as much as possible to use twisted pairs when routing the wires. I would not do it any other way for strobe and HID power feeds.
Click to expand...

FYI - I had originally grounded my strobes at the common firewall ground. You could hear the discharge in my headsets. I then made a ground right next to the central strobe power pack, located under the baggage compartment floor. The power pack ground and the termination for the shield grounds are tied to that platenut. The noise went away with this simple change. Note, the shield ground was not connected at the wing tip but was carried all the way through the wing root to the power pack.

Your mileage may vary.
 
shuttle said:
Thanks for that, Dan,

Regarding the "as much as possible", how far do you go?.......

I take the twisted pair from the HID ballast back to the switch.

Does the ground wire part company with the +ve there at the switch? Yes, most typically.
Or do you recommend skipping the ground wire around the switch and continuing the twisted pair to the breaker on the busbar? If easily done, this is the ideal.
I.e. How critical is twisted pair wiring on that breaker-to-switch wire section?
Click to expand...
Not critical.
 
Mel said:
No extra ground wire is necessary. Airframe ground is fine for all these applications; nav, landing lights, strobe p/s, fuel gauge senders, etc.
Mel...DAR
Click to expand...
Used local ground for the landing lights and pitot heat...
Works great, and simple..
 
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