Switches: spade vs screw terminals

Discussion of aircraft electrical system design, construction, and problems.

Re: Switches: spade vs screw terminals

Postby DCASonex » Mon Mar 06, 2017 11:05 am

wlarson861 wrote:The other thing about the good quality Fast-on's from aircraft suppliers is they have a small flared piece that is designed to capture the wire insulation. The cheapies don't have that and loose holding strength.

Those aircraft grade grade crimp terminals also require special crimp dies with separate portions to crimp wire and the portion around the insulation, not the standard el-cheapo ones in big box stores. (Especially avoid HF's cheap ones. Stripper, crimper I got from them for auto tool box went straight into recycled metal bin after first attempt to use it, would not fully close. Have found Stein Air Inc. to be another very good source for all aircraft wiring supplies and tools.

David A.
Posts: 510
Joined: Mon Sep 12, 2011 8:04 pm
Location: Western NY USA

Re: Switches: spade vs screw terminals

Postby builderflyer » Mon Mar 06, 2017 11:20 am

I use a quality crimper (the type David A just referred to) and quality connectors like those bought from B & C (not automotive ones) and I test each crimped connection by pulling on the wire to be sure it won't move from the connector. But, over time, a few of the wires have still surprisingly loosened from the connector. So I've gone to soldering the tip of the wire inside of the crimped connector to eliminate that possibility (being careful to not allow any solder to wick any significant distance up the wire especially to where fatigue of the wire could become an issue). Sort of like the "belt and suspenders" principle. Worth the extra time to me.

Art,,,,,,,,,,,,,,,,Sonex taildragger #95,,,,,,,,,,,,,,,,,,,Jab3300 #261
Posts: 66
Joined: Sat Jul 09, 2016 12:13 pm

Re: Switches: spade vs screw terminals

Postby n982sx » Mon Mar 06, 2017 12:17 pm

Frankly, after using nothing but spade terminals from B and C for my Sonex, I wouldn't even consider using screw on terminals. The fastons work great and hold well. Get a good crimper, good quality terminals and you're set. You'll never go back.

On my 14, I have a couple of places aft of the firewall where the component forces me to use a ring terminal to connect to a cheap screw mount and they are the most concerning to me.
Bob Meyers

Built and Flying Sonex N982SX http://n982sx.com
Building RV-14 N626KM (reserved) http://n626km.com
User avatar
Posts: 107
Joined: Tue Sep 03, 2013 11:45 pm
Location: Chicago, IL

Re: Switches: spade vs screw terminals

Postby WaiexN143NM » Mon Mar 06, 2017 3:59 pm

Hi all ,
Another good practice is to use some shrink tubing around the crimped connector and the wire. Helps support the crimped wire, and keeps moisture out.

Posts: 641
Joined: Mon Sep 15, 2014 1:04 am
Location: SF CA, Tucson AZ

Re: Switches: spade vs screw terminals

Postby lutorm » Wed May 24, 2017 9:48 pm

I've had spade connectors (OEM ones) vibrate loose on various motor vehicles, so I'm not fond of them at all. Maybe if you use high enough quality they're mostly OK, but I much prefer a connection method that has a positive means of retention. Also, if they're at all exposed to the elements, once you get some corrosion in there things are going to go downhill.

These days, there are many high-quality weather-sealed connectors one can use. I've used Metri-Pack, which are good for current-carrying wires but a bit on the large side, Ampseal (good if you have a lot of connections, like 23 or 40 pins) and Mizu P-25 (2-4 pin, tiny). You need an open-barrel crimp tool but nothing fancy, $30-40 bucks and you get something decent that works well once you learn how to do it.
Posts: 135
Joined: Mon May 15, 2017 1:35 pm
Location: The Island of Hawai

Re: Switches: spade vs screw terminals

Postby 9GT » Thu May 25, 2017 2:28 pm

For all your electrical and Avionics needs I highly recommend Steinair. They carry aviation grade and quality electrical supplies and avionics at GREAT prices. Phone consultations and advice are always welcome also. They generally ship on the same day ordered also. No relation,,,just a satisfied customer. http://www.steinair.com/
David Clifford
Howell & Gladwin, MI
RV-9A: Under Construction (I'm a repeat offender!)
RV-10: Built & Sold: Flying Since 2013 N959RV
Cozy MKIV: Built & Sold: Flying Since 2007 N656TE
User avatar
Posts: 28
Joined: Tue Apr 05, 2016 4:23 pm
Location: Howell, MI

Re: Switches: spade vs screw terminals

Postby NWade » Fri May 26, 2017 2:10 am

lutorm wrote:I've had spade connectors (OEM ones) vibrate loose on various motor vehicles, so I'm not fond of them at all.

That's understandable - most of the automotive spade terminals are crap - definitely loose and wide tolerances in size. I would never use automotive spade terminals in an aircraft. They look almost identical to decent-quality aircraft spade terminals, but they're not created equal. See my previous post on page 1 of this thread, where I illustrate some recommended and non-recommended terminals. The difference under actual connection and use is massive.


P.S. My Sonex is not yet flying, but I've used spade terminals for all of my Sailplane wiring for 10 years and never had a good-quality connector come loose from its fitting or have a wire drop out of a crimp connection, despite flying in all kinds of turbulence (rough air = lift)
Posts: 321
Joined: Mon Aug 08, 2011 3:58 pm


Return to Electrical System

Who is online

Users browsing this forum: No registered users and 1 guest