Ground cable to replace

[Vlad]

Wondering what kind of ground strap you guys have between airframe and the motor? A crack in a terminal has developed at 3K hours and I am looking for an alternative. Take a look.

[bullojm1]

Hi Vlad,

I used Welding Wire, which is composed of a number of very fine copper wires and has a lot more flex than the Tefzel wire you use, on top of better conductivity. I think the stiffness of the wire is a large contributor to your issue. PM me your address and I'll send you a couple of feet of it if you're interested.

Also, I used Aluminum Set Screw Lugs from McMaster-Carr - it's a lot beefier than the standard crimp lug. The pic below is for a smaller gauge wire (alternator). It's part number is #6920K21 - and I think I only paid $0.75 for it. You should be able to use that for a starting point to find the right size one for the ground wire.

[Vlad]

Thanks Mike that's a great idea about lugs. It's been too long since I was building. I do have the same lug at the alternator. My coworker is an electrician by trade and has tons of lugs in his truck. I also check with him on the wire and let you know tomorrow if able to source it. BTW how is your alternator belt holding? I am still on original and wondering if the time comes to change.

Added; is that red locktite?

[bullojm1]

Added; is that red locktite?

Yup, red lock tite...good eye! I also check it's tightness every annual.

[kevinsrv7]

Vlad,

You may want to use a braided cable like you have as your battery ground, that goes to your engine. flexible and designed for the task. It will reduce the flex load on the terminals.

[captain_john]

Russki, YOUR aging eyes picked up on that crack REALLLY nice!



You must be hanging around Billy again!



That is the kind of failure Mitch usually leaves for Sunday mornings before a long flight!



Don't listen to Mikey either! I am a PE (Professional Electrician) and I would and didn't use those Ilsco/Ideal lugs on my plane! Those are for amateurs and experimenters!



OTOH, Kevin (Yeah Dude) is on the right track. However, it isn't what I would do either...



I dare say the reason it cracked is because when you changed your battery last August it must have incurred some stress. Did you bend it by accident?

That being said, I have the GENUINE Burndy Mil-Spec Lug Crimper in my hangar. If you buy the correct lug from B and C, I will re-crimp it for you next you come here. It is a cheap, cheap... CHEAP repair! I think you plan on doing so soon?

How is that for a BAHGIN???

CJ

[Vlad]

CJ you know what? You damn right it's been under a stress. Three batteries changed, once in a while an oil wrench slips etc. Could be the reason not vibration as I initially thought. What's wrong with lugs? Seriously?

[captain_john]

Well, pick one up and stop by sometime! We can have you fixed up in a Jiffy!

I have an Electrical Code meeting both Saturday AND Sunday. I am available Saturday night though if you want to do it then.

No big HOOPING it up though. I need to be back on Cape Cod by 08:00 Sunday AM for my Code update class!

CJ

[Vlad]

Unable Saturday. Offered OT couldn't refuse extra gas roubles. Will coordinate with Billy a Sunday meetup wx permitting. Have fun at classes

[kevinsrv7]

Actually CJ Mike was right it cracked because the stress on lug from a stiff wire via engine vibration. Vlad use this and you will be a happy man. http://www.bandc.aero/braidedbondingstrap-1.aspx

[captain_john]

Yeah Dude! I also have a few extra feet of #2 MS22759 cable floating around. We can make a longer cable if need be.

...or fix this one for another 3,000 hours!

CJ

[bullojm1]

Don't listen to Mikey either! I am a PE (Professional Electrician) and I would and didn't use those Ilsco/Ideal lugs on my plane! Those are for amateurs and experimenters!

CJ,

Out of curiosity, what's wrong with the screw-type lugs compared to the crimp lugs?

[captain_john]

Mikey,

Absolutely nothing is WRONG with the ilsco lugs, I just wouldn't put them on my plane.

I have installed thousands of them and over my 30 years as a licensed electrician never seen one fail or cause a problem if it is installed correctly. That means using copper type on copper wires and aluminum type on aluminum wires.

Now, the loctite you have used wasn't part of the UL listing. If that were on a high voltage application, it would be a violation because it wasn't UL tested and listed be installed in such a manner. The possibility that you will go down in flames as a result??? Probably not... That is a violation of National Electrical Code 110.3 (b)

The reason why I don't like it is because it has a higher parts count, more weight, complexity, isn't insulated or stress relieved. Additionally, my terminals are filled with solder so that they are gas tight connections. Something that you can't do with the ilsco lug.

My two...

CJ

[Vlad]

OK fellers today I sourced the cable and lugs. Price - free. Can't afford to pay more just logged another 1.4 h on the hobbs today. Will it ever end?
CJ take a look at the insulation. You can quote Electric Code by heart can you tell me the temperature this insulation is good for?

[captain_john]

Russki,

The actual type of insulation is shown to the left of all that writing. It is probably and XLPE or THHN/XHHW. Very common building wire...

Either way you slice it... probably a 90 degree C conductor. That COULD be the T90 mark on it.

What size is it, #2 AWG? I have some here if you want to make a new one.

Let me know. I might even have the lugs too!?!

CJ

[Vlad]

Thanks CJ. I will frequent your woods next month or two will catch you

[bullojm1]

OK fellers today I sourced the cable and lugs. Price - free. Can't afford to pay more just logged another 1.4 h on the hobbs today. Will it ever end?

Lookin' good VLAD! How large is that wire...it doesn't look to be 2 gauge? I dont think the insulation material makes much difference for the engine ground -- most people use a braided uninsulated cable.

- Mikey B