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Wire Connections to an Outlet
By Dave Rongey
How Tight the Screws Should be for Wire Connections to an Outlet
Electrical Outlets Question:
I have replaced a good amount of receptacles in my home, and I'm the type of person that worries about every last thing possible and mainly about burning my house down.
I know that loose connections are bad and very dangerous.
Whenever I loop a wire around a receptacle screw terminal I make the screw very tight to ensure and snug connection (as tight as I can with my screwdriver).
What I want to know is if this will be okay. I have read somewhere that you can flatten the wire from over tightening the screw and create extreme heat.
I just want to know if this will burn my house down, or if it is okay left alone. We have not had any problems with any receptacles, and they are all cool to the touch.
If you could get back to me with that answer, that would be great.
Thanks a lot. Matt
Hi Matt - Great Electrical Repair Question!
First of all - would you PLEASE tell me where you found the information about tight screws. You are the second person to share this concern and it is false, especially when it comes to solid wire on an outlet screw terminal. There may be a slim possibility of flattening a #14 wire down to the point of breaking the wire off, but I have never seen such a problem on an outlet.
I have personally stripped out the screw a few times, and even broke the screws off when tightening down #12 solid wire on outlets. The only place I would advise caution would be inside the panel when tightening the mounting screws down on #14 solid wire where it attaches to circuit breakers and especially neutral and ground busses. The mention of an overheating Tight Connection where the wire is flat is in my mind incorrect.
Tight connections do not cause fires, loose connections do. Loose connections arc when the wire or circuit is under a load. I should point out that wiring outlets are typically done using two methods - Series and Parallel. The Series method can create problems because the load of the whole circuit travels through each device, whereas using the parallel method this is not the case - only the load for each individual device is fed through that device or outlet.
Here is a brief explanation of these methods where two sets of romex type-nm cable wires are in each outlet box:
Series is where the two wires of each color are attached to the outlet terminal screws, blacks on the brass colored screws, white on the silver colored screws, OR the wires are stripped and pressed into the rear push-a-matic connections for some brands of outlets.
This method can cause problems, especially when space heaters or large load devices are plugged into the circuit, the load is placed through each outlet wired with this method.
The Parallel method is where the two wires of each color are pigtailed or spliced using wire connectors to a third wired which is then connected to the outlet. With this method the load travel trough the splices, not the outlets.
As long as the splice is done properly by twisting the right length of wire and firmly screwing on the wire connector there should never be a problem. Now I know that there are situations with older homes where there are the smaller metal outlet boxes that do not have enough room for the pigtail splices, so in this case you will need to use the screw terminals. The ground wires for each method are typically twisted and spliced using a ground crimp. If a high consuming device is used such as a space heater then I would install a dedicated circuit and outlet for it.
Thanks a lot for your quick answer to my question, I feel better about it now.
I saw that you mentioned pig tailing the wires together by twisting them and then using a wire nut. I have always used the Ideal brand push in wire connectors in receptacles. Will these be okay left alone? If a wire should pop out in the future due to heating from a heavy load, is there a good chance that this could burn my house down, or will something simply stop working?
Thanks a lot.