John Drake Services, Inc.
1427 E. 68th Street
Long Beach, CA 90805
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Connections for Wiring
This is a work in progress.

There are many ways to connect wires in a low voltage direct current system.

First off - always shut down the power before working on electrical systems
and wear eye protection.

We will discuss permanent, semi-permanent and removeable connections.

Always avoid putting stresses on any connection - this is for your safety.

The more mass (metal) a connection has - the more amperage it can handle.
If you use a light weight connector on a high amp circuit - disaster will follow you.

Permanent connections:

These are connections that once put together, the wires have to be cut to
remove them.

I won't say much about this as I can't make a solder joint to save the world.
If you choose to solder your connections please make sure they are clean
and once done, insulated for safety.

wire nuts:
wire nut
These are commonly used in buildings and can have a place in a
low voltage application with some diligence on your part.
First off, I Do Not recommend this in mobile (vehicle) applications as
the vibration of a moving vehicle can cause them to come loose and
create an arcing condition.
Always read the instructions and follow them, you can do it right or
wrong - doing it right the first time is safer and easier.
In a low voltage application they are fine for low amperage circuits -
not for charging systems nor d.c. to a.c. inverters.
Basically you strip the wires and insert them into the proper sized wire
nut (they are color coded and the package will show you how many
wires - and of what gauge, they will handle) and twist the nut until the
insulated part of the wires start to twist.
I would also recommend that you use an oxygen barrier paste or goop
to prevent corrosion.  

crimp on connectors:

crimp on connector

These consist of a plated steel sleeve and a press on insulating
You strip your wires, slip them into the sleeve and crimp (crush) it.
Then you slip the insulating cap over the connection until it snaps
in place.
Don't over crimp them as the sleeve will become distorted and the
cap won't fit in place - I have done that a few times.
I always add oxygen barrier goop when done.
These work well in both a mobile or stationary system.

insulated butt connectors:

insulated butt connector

I have used zillions of these.

First off, we have not pictured uninsulated butt connectors as
the insulated type are readily available in 22 to 8 gauge sizes.
Larger than 8 gauge are usually not insulated and can be tricky to
use. If you use them, always insulate them with a heavy heat
shrink tubing after the connection is made.

In the butt connector is a metal tube with two stops in the middle.
You strip the wires, shove them in and crimp the metal tube - it stops
at the flare in the plastic insulation.

They work well in low to medium amperage connections and have been
used in the automotive industry for decades.

Again, I recommend using an oxygen barrier when the crimp is completed.  

Semi-permanent connections:

quick cable magna lug ring terminal

quick cable max copper lug compression lug

These connectors are designed for permanent connections but can be
dis-connected without cutting the wires.
Basically just unscrew the nut holding them in place.
The smaller sizes, which are usually insulated, are called ring terminals and the
larger ones, usually un-insulated, are called cable lugs.
These are available in sizes from 22 gauge to 6/0 (250MCM) gauge.

The insulated ones are designed to be crimped onto the wire.

The un-insulated ones can be soldered or crimped on - I preferr crimping them.
It is always recommended that heat shrink tubing be used to cover the barrel
(where the wire goes in).
I use heat shrink tubing on my connections.

Try to get the hole size of the pad end of the lug as close as possible to the
terminal size as possible.
In a quality lug, the hole size marked shows the size of the terminal it will fit over.

The last one shown above is a compression lug.
You strip the cable, slide the collet (the small piece with fingers and threads)
over the cable.
Then you screw the lug body (always turn the lug, not the collet) onto the collet.
These are made of cast copper and are quite pricey but you can make a heavy
duty connection with just an adjustable wrench and a screw driver.

Don't go cheap on connections.
First off for safety, a connection is usually the first place to show arcing and/or
heating in a poorly designed system.
Secondly, poor connections can drain power from your system.

Removeable connections:

There are many applications where you need to connect or disconnect a device
without the use of tools.
Most cars come from the factory with modified cigarette lighter receptacles
labeled "power connector".

We will show these in order of reliability and power handling capacity.

cigarette ligher plug:

male lighter plug  female corded lighter receptacle

lighter plug wall receptacle    lighter plug and sae connectors

It was not that long ago that most people in off-grid homes used these just
about everywhere.
I remember putting a lighter plug in and twisting it until a good connection
was made.
You will find them on mobile devices, spot lights, fans and the list goes on.
They work well in low amp draw applications.
The quality of the male plugs and female recepticals run from okay to throw
it in the trash as you
leave the store.
I can not recommend them for applicatons over 5 amps at 12 volts d.c.
Many high amp draw devices, such as low wattage inverters and
floodlights, come with these but
the quality is usually better than most after market ones.  
It is not unusual to see these with internal ten to fifteen amp fuses - to me
this is an advertising gimmick and should not be taken at face value.
Always buy the best quality you can find.

SAE connectors:

sae connector set  panel mount sae connector rv roof  panel mount and standard sae connectors

Here is where we find something that can handle some decent amperage
(as long as the wire size and length is appropriate) and is easy to use.

These are polarity specific and are used so many applications I won't
even try to list them.
I always recommend buying these made in the U.S.A. as the imports
don't always work out so well.
As with all things electrical - go on the cheap, then wait for the smell
and smoke to start.

SB (storage battery) connectors.    

anderson sb connector shown with cable clamps
 anderson sb with quickcable cover protective cover   safety boot on sb connectorsafety boot

These are my first choice for easily disconnectable high amperage connections.
There are many variations of this idea but the ones shown are two conductor
Anderson sb connectors.
These come in different colors - grey will only fit with grey,
red only with red and so on.
This is done for safety in areas which have different voltage systems.
First off, make sure you are buying quality connectors - they are safer
and will last longer than the cheapo ones.
A good quality connector will have copper contacts that have been
silver washed or tin plated for corrosion resistance.
These can be disconnected while under power.
We have sold have sold several thousand of these, that is until
the fall-apart imports showed up. Yes, I do have my own opinions.
I use these here for most of our portable systems.
They are available in 50 amp (as shown), 175 amp and 350 amp sizes.
Mechanical release kits are available for the 175 and 350 amp sizes
to be used as a disconnect.
There is no male or female - just rotate one and they will mate
together and maintain polarity.
Covers for the mating ends are available to keep the contacts clean
when disconnected as well as safety boots for the wire end.
Shown are brackets that take the stress off of the wire connections
in the back end of the internal contacts.   

light harnes with different connections

We have two Thin-Lite LED VFI lights over the packing area.
Each one is hanging by chains to the right height over the floor
and packing table.
They have an Anderson SB50 connector on the wiring leads.
Each has a wiring harness like the one shown above.
In an emergency, like an earthquake, they can be quickly
The harness has an SB connector on one end to connect to the
The other end has an SB connector, battery clips, and a male
lighter plug.
This will allow the light to be used with any 12 or 24 volt d.c.
battery source.