Timeline for How many wires can be connected to the C terminal at the furnace?
Current License: CC BY-SA 3.0
12 events
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| Jun 18, 2016 at 0:29 | comment | added | Harper - Reinstate Monica | It's normal for the W wire to have a wire going to it for each thing controlled by the thermostat (gas valve, fan, A/C, etc.) , since it's here that the circuit is completed. If in doubt, pigtail it, the "blue" wire nuts are the right size. | |
| Dec 18, 2015 at 22:40 | comment | added | Tester101 | @user46790 You could use an ammeter to measure the load, or use the values printed on the various devices. If there's only small loads (contactors, relays, etc.), you're probably okay. | |
| Dec 18, 2015 at 19:53 | comment | added | user46790 | Tester 101: I just saw the other piece of (very useful) information. I do I make sure that the additional load can be handle by the transformer?? Is there any way to check it instead of waiting to see if any damage to the fuse or the transformer occurs? | |
| Dec 18, 2015 at 19:37 | comment | added | user46790 | @Thester101: If there is not a problem with "overworking" the C-terminal using it for three sources, I will follow your suggestion and use a pigtail then. Thanks a lot | |
| Dec 18, 2015 at 19:19 | comment | added | Tester101 | @user46790 Added a bit more information to my answer, hope it's helpful. | |
| Dec 18, 2015 at 19:18 | history | edited | Tester101 | CC BY-SA 3.0 |
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| Dec 18, 2015 at 19:10 | comment | added | Tester101 | Don't assume. If the terminals are allowed to have more than one wire, it will say so on the terminal block or in the manufacturer's documentation. Two wires per terminal in HVAC work is common (though not usually correct), while 3 or more will tend to use a pigtail. | |
| Dec 18, 2015 at 19:03 | comment | added | user46790 | Ah... and those were professionally installed, so I would assume that more wires are allowed, not just one. But is 3 too much?? | |
| Dec 18, 2015 at 18:59 | comment | added | user46790 | Yes, I'm asking if I can use the C terminal with three wires. Most of the furnace terminals are already sharing two wires... as you can see from the picture (Com, Y and R). | |
| Dec 18, 2015 at 18:56 | comment | added | Tester101 | @JPhi1618 If I remember correctly, NEC says one per terminal, unless the terminal specifically states that more are allowed (110.14(A)). At any rate, we're talking about 3 wires, not 2. | |
| Dec 18, 2015 at 18:53 | comment | added | JPhi1618 | I assumed the type of terminals pictured were "made" to have 1 wire on each side if needed like on a backwire electrical outlet since the screw is clamping the wire between two plates. | |
| Dec 18, 2015 at 18:50 | history | answered | Tester101 | CC BY-SA 3.0 |