carter system

[imported_Rob]

Looking for an explanation on the carter system-- three way switching.Thanks

[Wgoodrich]

Rob, Sorry I don't recognize the term. It sounds like a local slang identifying to a certain wiring design of a three way system.

We have what is called the Kentucky three way. No offense meant to Kentucky, fish in that state all the time. What is referred to in my area as a Kentucky three way is a pull chain in the middle of the room with a string ran to a loop holding the end of each string to pull that pull chain from three different doors.

Then there is the illegal use of both the grounded leg [aka white neutral] and ungrounded conductor [aka hot wire] both in a switch system using only two wires between two separate buildings, if I remember right. While this is improper and unsafe wiring per NEC that forbids switching of a neutral or grounded leg [aka neutral wire] it can work and was used back when we wired by the seat of the pants without Codes telling us not to that it is unsafe to do. This I am suspecting is the three way system you are referring to as the Carter system. Just not sure.

Hope this helps

Wg

[imported_joed]

It is also known as a california 3way or a chicago 3way. It is illegal under the curent NEC. It goes like this I think.
Connect the hot and neutral to the traveler screws of 3way #1. connect the light to common of both 3ways. Connect hot and neutral to traveler screws of other 3way. If both switches are on hot or both are on neutral no light. Switch either one and you have light. Problem is in one settings the shell of the light is hot.

[Wgoodrich]

It is not only against the NEC rules it is a highly risky shock hazard.

This is one of those don't do it that way situations. Use an approved three way switch design per NEC minimum safety standards.

Be Safe

Wg

[petervagn]

imported Rob,
i ran into a "carter wire" system once with knob and tube and hope i never see it again.
first, i'm not an electrician by trade, but i've been renovating homes for 24 years. i know what should be left to properly trained tradesmen.
the carter 3way i was working on had 110 power at both switch boxes with all lights and switches removed. i called an old friend who once was a electrcian, and he was surprised there was still any of it in service. with the switches out, the two wires that light your test light go to the screws of the same color. the other wire goes to the common terminal. this worked for me and i hope it will you also. this job was 15 years ago, and i still have the scrap of paper i took down his insrtuctions on.
be careful, peter

[Homer]

In the spirit of keeping a 4 year old thread alive, here's my 2 cents.

The Carter System was a dangerous way to save a wee bit o'copper. It is a major NEC violation. The diagram is for historical education purposes only.



Homer