Screw down wire or use crimp terminal

[summerofgeorge]

I know this has been discussed before but I can't find the thread I'm looking for. My contactors and breakers for my panel have screw down terminals. Is it better to just screw them down on the wire or should I crimp the flat terminals to the wires and then screw them down? I'm referring to my 30A stuff too if that matters.

Also, how do you use a ratcheting crimper? What I mean is does the terminal need to be in the crimper a certain way (since it crimps each end slightly different)?

 

[BigFloyd]

IMO, it's better to add a connector and slide that into the terminal to be screwed down. You have more contact surface and it's more secure.

For high current applications, I also like to crimp then add a bit of solder. There are a lot of connections in that panel and I want every one of them to be rock solid.

 

[processhead]

10 and 12 gauge stranded wire does not clamp under a screw terminal very effectively and has a tendency to work loose.

Loose strands can turn into potential short circuits if they come in contact with other connections.

That is the main reason for using a crimp terminal with stranded wire.

Ratcheting crimp tools are used to ensure a consistent, positive pressure on the terminal.

 

[ChocolateMaltyBalls]

^those guys are right. I'm surprised there aren't male terminal connectors on those parts, that's a lot power to just rely on pressure from screws, unless they are small enough for 10ga ring terminals.

Ratchet crimpers make a build so much easier, just make sure there's a little bit of copper showing on the terminal side of the connector so you know the wire is seated well into the connector and line the edge of the metal sleeve with ratchet teeth. As far as I know most crimpers apply even pressure across the connector. IMO with crimp on connectors using a ratchet there's no need for soldier.

 

[grandequeso]

I wouldn't complicate things. If you have screw terminal available use it. As long as it is rated for the awg (size) of wire you are working with you will be fine.

 

[hio3791]

I had similar concerns when building my control panel. I used crimp terminals for every connection, except for the 10 gauge wires going to/from the contactor and the L630R. I screwed those down very tightly. My rationale was that when I wired the gfci breaker and 4-prong dryer receptacle (using 10 gauge stranded wire), those connections are also screwed down (very tightly). There was no option of using crimp terminals on those. In my service panel, I saw other 10 gauge wires going to 30amp breakers that were also screwed down.

I am not a licensed electrician but I assumed that if my service panel passed inspection and it's been fine for nearly 20 yrs, then I should be ok.

 

[P-J]

No crimp terminal - just strip the wire end, twist it tight and then flow solder into the wire to bond it. Job complete.

 

[atoughram]

Crimp connectors introduce another failure point and are pretty much unknown in the machinery world now. A loose connection is a fire hazard. Some terminal strips necessitate the use of them though and I avoid using them. Terminal screws with square washers such as the screws on the back of many popular PID controllers easily take to crimping bare wire under them. The only places I've used crimp connectors in my rig is on larger wires (10AWG) when necessary.

 

[ForestGroveBrewer]

What is the screw down terminal rated for??

 

[atoughram]

What is the screw down terminal rated for??

Depends on the size - but it should be either stamped on or with the documentation.