how to connect ground to Airconditioner


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Old 05-16-11, 05:32 PM
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how to connect ground to Airconditioner

I basically am replacing the metal conduit that has rusted out with pvc and liquid tight. I assume I need to add a ground wire because the metal acted as the grounding previously is gone.

the line side is from a 1970 5 ton Air conditioner install and they used #4 wire for the 2 hots as well as a #6 or #4 for the ground. the load side hots are #6 wire going to the new Air conditioner so they seemed to have downsized for the Air conditioner, its on a 65 breaker.

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do I just use this lug nut and put my added ground above and tighten or do I pigtail 3 wires together and put one wire on the lug on the box?

the line wire feeding is #4 but the load wire is #6 would a #8 ground be ok to use for the ground?

I see no other ground going anywhere from the Air conditioner junction box, is this the correct thing to do (adding a green ground wire back to main panel)

thanks for help in Advance!
 
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Old 05-16-11, 06:11 PM
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Assuming the green grounding conductor is the line side ground, I'd add a ground lug to the disconnect panel/box and run a #10 green grounding conductor to the new unit. Do not double up ground wires in that one lug, it is only rated for one wire.
 
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Old 05-17-11, 12:23 AM
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thanks reply Joe

Hmm so pigtailing the 3 things, 2 grounds (line and load) and then adding a 3rd wire to the lug in the ac box wouldn't work?

Thats the way I would usually wire a junction box. I just don't know if code is different for AC box.

I guess I could add a second lug also.

Hmm food for thought
 
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Old 05-17-11, 07:52 AM
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Hmm so pigtailing the 3 things, 2 grounds (line and load) and then adding a 3rd wire to the lug in the ac box wouldn't work?
There should be two wires. Line ground and load ground. What is the third ground?
 
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Old 05-17-11, 09:49 AM
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Sorry for confusion, I counted line and load and then a 3rd short wire which attaches to the lug in the box. Sort of like image below only instead of the 3rd wire going to the switch as it does in image it would attach to the lug in the ac junction box. Like you would handle when you pigtail the ground to add the ground screw in a metal box when adding a receptacle.

If you look at this page and scroll down to
4. Inside: Installing the Switch (the second image)


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Maybe this Idea is bad I had, I am just wondering if it is #8 green from line and #6 wire from load and a 3rd #8 to the lug, I am going to need a huge wire nut and its going to be hard to twist all together, maybe I should add the lug as suggested above and bond them together or maybe a little ground bar kit? grr not sure.
 
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Old 05-17-11, 10:13 AM
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To fasten the grounds you could use a small ground bar with lugs, a split-bolt connector or a crimp barrel.
 
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Old 05-17-11, 10:25 AM
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Ok thanks for the information

Ok wire nut idea is out! I will use one of those items you listed, probaly the Ground Bar but I will look up the other items also to see what they are and how they work.

Thanks to all above for the help in wading through this project!
 
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Old 05-17-11, 11:51 AM
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If the lead is just bonding the lug to the box, the box is metal and the lug is fastened to to the box with a machine screw you don't really need it.

Note you can probably use #10 for load ground. 65a is an odd size for a breaker. The usual size breaker is 60a. For 60a breaker #10 is acceptable. What size breaker is at the main panel?
 
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Old 05-17-11, 05:29 PM
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so pigtailing the 3 things, 2 grounds (line and load) and then adding a 3rd wire to the lug in the ac box wouldn't work?
Yes, that would probably work, but by the time you split bolt the #8 or #6 with two more wires and insulate them properly with rubber tape and vinyl tape, you'll have a wad. In my opinion adding another lug is the quickest, cleanest and least expensive way to do this. Adding a ground bar would also work if you happen to have one on hand.
 
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Old 05-19-11, 08:40 AM
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Thanks replys

If the lead is just bonding the lug to the box, the box is metal and the lug is fastened to to the box with a machine screw you don't really need it.
True just sort of paranoid on my part a extra precaution, if the bolt came loose (lol earthquake or something) or I didn't make a great connection to the metal, your right not really needed though.

65a is an odd size for a breaker. The usual size breaker is 60a. For 60a breaker #10 is acceptable. What size breaker is at the main panel?
your right again its a 60 amp not a 65


adding another lug is the quickest, cleanest and least expensive way to do this
.

I agree Joe after thinking through this, I can leave the load wire alone and just add one lug to add the line wire. least messy etc.


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One last question for curiousity, What is that thing in the picture above in the ac junction box, it sort of looks like a door knob knocker. the curved metal bar, in a yourube video I saw someone pull it out, my guess is it is some kind of breaker what is its function?

Thanks again for all the help!
 
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Old 05-19-11, 11:05 AM
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Disconnect. It acts as a switch to turn off power to the load when pulled out. Usually they can then be turned around 180 and reinserted without the circuit being re-energized.
 
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Old 05-19-11, 11:30 AM
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ah thank you for the info, so I guess technically this would be a Ac Disconnect box not a junction box.
 
 

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