Contactor Coil Wiring - Electrical - DIY Chatroom Home Improvement Forum

Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Electrical


Thread Tools Display Modes
Old 04-30-2008, 08:58 AM   #1
Join Date: Mar 2006
Location: Chicagoland
Posts: 15
Rewards Points: 10

Contactor Coil Wiring

I have a 220V contactor with a 120V coil in it which I use to start my air compressor. The coil works fine, but I am curious about what the two poles numbered 2 and 3 are used for. These are located above the poles that receive the 120V and neutral wires as in the picture. Can anyone advise me on these?
Attached Thumbnails
Contactor Coil Wiring-coil1.jpg  


dmend is offline   Reply With Quote
Old 04-30-2008, 10:32 AM   #2
Join Date: Feb 2008
Posts: 326
Rewards Points: 250

Contactor Coil Wiring

Hard to see by the picture, but lots of contactors have extra sets of contacts to be used for holding contacts or whatever else, it depends on the circuit design


Silk is offline   Reply With Quote
Old 04-30-2008, 11:06 AM   #3
Idiot Emeritus
Join Date: Mar 2008
Location: Fernley, Nevada (near Reno)
Posts: 1,776
Rewards Points: 1,346

Contactor Coil Wiring

The starter contacts labeled 2 and 3 are used as a latch in conjunction with start-stop buttons. These contacts are wired in parallel with the start button. Both the contacts and the start button are normally open (off). When the start button is pressed, the coil is energized, pulling the contacts closed, thus simulating holding the start button in. The stop button is normally closed (on), and is wired in series with the control power. When it is pressed, the coil is de-energized, and drops out. It stays de-energized because the 2-3 contacts are now open, waiting for the start button to be pressed again.

A pressure switch control doesn't need a latch, because it stays closed (on) until cut-off pressure is reached, then it opens (turns off). This is called a maintained contact, the start button is a momentary contact. Think of the pressure switch as a light switch, and the coil is the 'light'. Switch turns on, light (coil) turns on; switch turns off, light (coil) turns off.

micromind is online now   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Oven wiring rodsteryz Electrical 1 12-26-2007 02:26 AM
Replacing wiring in middle of run, ungrounded lighting circuit alexz Electrical 3 07-05-2007 09:53 PM
Trane Heat Pump tstat replacement with Honeywell prog - wiring question sep23 HVAC 2 10-20-2006 10:10 PM
Knob & Tube wiring - How concerned should we be? hotdiggitydog Electrical 6 04-11-2006 08:52 PM
Garage - Protecting wiring installation eastment Electrical 4 11-26-2005 12:52 PM

Top of Page | View New Posts