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Hi everyone new to the site. I am an hvac tech and don't do alot of installs. Did a furnace and a/c unit and the outside condenser had only two wires instead of 3, anyway the house has conduit so tried to run ground wire back to main, because thats the right way. Whats confusing me is when the old unit was installed they used the conduit as a ground, right. The panel[main] has a wire going from the conduit to the neutral buss. As a matter of fact the bare grounds also go to the neutral buss which is the ground buss also. When you put my dvm on the ground buss and conduit I get 110v, thats not right I shouldnt have voltage from the ground to conduit,right. The grounding on older houses can sure be confusing. You would think neutral would be seperate from ground, but it isnt, sorry for ranting just want to get it right and saf, thanks
 

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Hi everyone new to the site. I am an hvac tech and don't do alot of installs. Did a furnace and a/c unit and the outside condenser had only two wires instead of 3, anyway the house has conduit so tried to run ground wire back to main, because thats the right way. Whats confusing me is when the old unit was installed they used the conduit as a ground, right. The panel[main] has a wire going from the conduit to the neutral buss. As a matter of fact the bare grounds also go to the neutral buss which is the ground buss also. When you put my dvm on the ground buss and conduit I get 110v, thats not right I shouldnt have voltage from the ground to conduit,right. The grounding on older houses can sure be confusing. You would think neutral would be seperate from ground, but it isnt, sorry for ranting just want to get it right and saf, thanks

HVAC guys do wiring as well?

You would think neutral would be seperate from ground, but it isnt
Only if the panel was a sub-panel would the neutrals and grounds be seperate. If they were not tied together at the main disconnect, then the ground wire would be worthless.
 

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If I were in your situation, I would tell the customer they need to have an electrician come out to connect the outside condenser.

I would do this even if I knew how to connect it. My reason for this is CYA. With some customers, do ANY work on their electrical panel, then a problem crops up in the future, then they are on the phone to YOU!
 

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If it's in metal conduit you do not need a another ground, you have one, the conduit. The conduit is bonded at the service panel by way of your explanation. Unless this conduit run is broken somewhere, you are good to go. Is the wire size correct?
 
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