10/30/2013

Marine Wire Connectors

Marine Wire Connectors, Making Quality Small Wire Connections

When discussing marine wire connectors there are many styles and instances for particular connectors as well as the methods of installation to consider. I'm sure you will come across many opinions as to the proper way to make a wire connection for your boat and hopefully this article will leave you better educated so you can form your own opinion. 

Small Wire Connections

When discussing small wire gauge connections we will be referring to the most commonly used primary wire sizes which would be size 8 AWG and smaller. In most cases
the small wire connectors are typically grouped in 22-18 AWG, 16-14 AWG, and 10-12 AWG as the most commonly used sizes and connectors are usually color coded to the size groups as follows:
  • 22 AWG - 18 AWG is RED
  • 16 AWG - 14 AWG is BLUE
  • 12 AWG - 10 AWG is YELLOW
  • 8 AWG is PINK
Small wire connectors are available in different styles as well. There are ring terminals, fork terminals, butt splices, tab style quick disconnect, as well as bullet style and some other less common. When it comes to attaching the connector to the wire there are two methods, soldering and crimping. 
The ABYC (American Boat and Yacht Council) states that:
Solder shall not be the sole means of mechanical connection in any circuit. If soldered, the connection shall be so located or supported as to minimize flexing of the conductor where the solder changes the flexible conductor into a solid conductor. 
 EXCEPTION: Battery lugs with a solder contact length of not less than 1.5 times the diameter of the conductor. 
NOTE: When a stranded conductor is soldered, the soldered portion of the conductor becomes a solid strand conductor, and flexing can cause the conductor to break at the end of the solder joint unless adequate additional support is provided. 

So basic understanding is that the stranding of the wire provides the ability to absorb vibration and resist breaking of strands.  When you use solder you take the functionality away from the stranded conductor by transforming it into a solid mass and making it more susceptible to breakage and failure. There is an effect known as "wicking" where the solder will flow up between the strands past the point of solder and into the stranding covered by the wire insulation. The wicking of the solder into the strands provides additional means of failure so the ABYC states that if a stranded wire is soldered "adequate additional support" should be provided to minimize the potential for damage.

While a crimp made with the correct crimping tool as recommended by the connector's manufacturer is suffice to make the connection suitable in the marine environment, many folks insist on adding solder because they feel it gives them piece of mind. The problem arises on how the solder is added. If soldering first and then crimping you'll basically be crushing the solid solder mass and potentially breaking strands. The second method is to crimp first and then feed solder in from behind but a properly crimped connection will not allow solder to flow past the crimped connection causing the solder to sit behind the crimp and wick up into the strands and up into the insulation serving no real additive benefit.

The only really suitable, properly thought out solder and crimp combination are a certain style of butt splice where a stripped wire is inserted from each end and crimped. Then after the crimp is complete, there is some solder in the middle of the splice between the crimps which will flow when the splice is heated and flow into the two wires strands. It's a pretty cool set up, but again, most likely unnecessary when properly crimped with the correct tools.

Rings and Fork Terminals 

There are ring terminals and fork terminals and each has a benefit in the marine environment. It is preferred to have a ring terminal installed as it provided the most secure installation, totally surrounding the screw or stud that it attaches to. A fork terminal adds the benefit of a more simplified removal since a screw can be loosened and the fork style connector can be removed without having to totally remove the screw. 
In the marine environment there are two types of fork terminals that are acceptable which make their simple "falling out" less likely to occur. These two types are:
  • Flanged Style Fork- the fork end has a bent up end which will resist being pulled straight out when properly fastened to the screw. The small bend at the end of the forks will keep the fork in place even if the screw holding the fork terminal became slightly loosened. 
  • Locking / Captive Style Fork- the fork end tapers in a manner as to allow the fork to "snap" onto the screw post. The taper creates friction and force must be applied to insert the fork or remove the fork from the screw post regardless of the screw's tightness. 
Of the two forks above, the locking / captive style fork is the more secure option since it would remain on the stud even should the stud loosen while the flanged fork would eventually fall out should the screw loosen past a certain point. 

The ring terminal is a no-brainer secure solution as it totally surround the screw or stud and requires the total removal of the screw or stud in order to facilitate removal or the ring terminal. The ABYC states: 

Ring and captive spade type terminal connectors shall be the same nominal size as the stud. 
Pretty self explanatory, the nominal (in name only...means commonly referred to) hole size should be the same as the stud or screw size so that you should use a 1/4 inch hole terminal on a 1/4 inch stud. This will make a nice, tight and secure connection between the terminal and screw and stop the terminal from moving around.

Friction type connectors, tabs and bullets etc:

The ABYC has the following to say about friction style connectors:
 Friction type connectors may be used on components if 
1. the circuit is rated not more than 20 amperes or the manufacturer's rating for a terminal designed to meet the requirements of UL 310, “Electrical QuickConnect Terminals”, or UL 1059, “Terminal Block”s, and
2. the voltage drop from terminal to terminal does not exceed 50 millivolts for a 20 amp current flow, and 
3. the connection does not separate if subjected for one minute to a six pound (27 Newton) tensile force along the axial direction of the connector, on the first withdrawal.  
The most prevalent style  is the tab style connector like the 1/4 inch tab style quick disconnect tabs in female and male configurations. The female connectors are often used to attach to switches, blocks and other electrical components.