Electrical Question

[Ted in NE-OH]

If I run two seperate 120 V circuits in a EMT conduit do O need to also pull TWO ground wires?

 

[zuhnc]

No, but ensure that it is one continuous ground, if going to two different places at the end. This ensures if one device at the end (outlet, say) is disconnected, the device on the other line still retains its ground. This is the equipment ground and is not supposed to carry any current, if properly installed.

I would recommend installing two complete circuits, however, hot, neutral and ground, Tape the wires of each circuit together at the end when installing to ensure the hots and neutrals are together, for each device.

You WILL have to have TWO neutrals, though, one for each device, if two separate circuits.

What size conduit, and what kind of wire? Keep in mind conduit fill for wire size and type of wire.

I am not a licensed electrician, but I do install electrical things according to the NEC. zuhnc

 

[kencombs]

Not everyone supports the idea, but it is legal per the NEC to used the conduit as ground. I do that, but also use all compression because, IMO, they provide a more reliable electrical connection to each stick of conduit and boxes. If you do that be sure all recepts and switches are grounded to the boxes.

/there is also a legal way to run two circuits with one neutral(white) wire, called a Multi-wire branch circuit. That requires a two pole breaker to serve the two circuits.

So you could use conduit and 3 conductors to get two complete circuits if you so desire.



Rather than taping circuit pairs together I use different colors of wires, say red and black to ID each one. Whites don't matter. Helps if working on it later.

 

[Hemmjo]

Just to be clear. You only need one ground, either a properly sized conductor or properly a connected metallic conduit system.

If you are really asking about the neutral conductor, you need 1 OR 2 depending on how the hot conductors originate.

If the hots are on different single pole breakers, AND if those breakers are on THE SAME pole in the panel, you need TWO neutral conductors.

If, as suggested in another post, you use a double pole breaker, each hot will be on different poles. In this case you only need ONE neutral conductor.

I do not intend to be condescending here, but many people use the term ground and neutral interchangeably. They are different, even though they both eventually lead back to ground potential.

 

[Geo-TH,In]

220v are two 110 vac.
So use 4 wires, two 110 v power wires that will make 220v, one neutral and one ground.

If you measure the current in the neutral wire when you have two separate same size 110v loads, you will measure zero current. So your neutral wire can be the same wire guage as your 110v wires.

 

[moresmoke]

Grounding using wire vs EMT. My preference is to run a ground wire for any outlet circuits. Things like overhead light circuits I will be cheap and rely on the conduit. Not as likely to be touching the lights if there were a problem.

 

[Stephen Newell]

If you mean a neutral wire, you will only need one. If the conduit is grounded to the box you wouldn't necessarily have to run a ground wire but it would be better if it had one. The conduit could loose it's ground and you would then be without one.

 

[paul]

120v has a hot, a neutral, and a ground.

Many people confuse the neutral and the ground, so its best to ask if you really mean the ground wire for sure?

Paul

 

[Janicholson]

Separate circuits is still ambiguous in that they can still be connected to the same leg of the utility company service (L1 and L1), or on opposite legs (li and L2). The difference is important in that the two circuits, though on different breakers, could, in the L1/L1 situation have literally no voltage measured between the Black/hot wires, while the L1/L2 situation has 240 between the Black hot wires. Personally I would wan to know if there was an intent to operate 240 devices. Keep your thinking focused on the difference between a potentially bare or green wires, and the neutral white wires. Jim

 

[buickanddeere]

Hospital applications require a dedicated ground and a dedicated neutral for each circuit .
I have to give you full points for installing a ground in EMT or Rigid conduit . So many times a circuit is left without a bond to earth due to rusty or busted conduit after a cheapskate installation . Without a ground wire .

 

[dr sportster]

No

 

[John T]

In the jurisdiction at the time I practiced power distribution a single EGC sufficed for two 120 volt branch circuits fed from The service panel. FYI with multi wire branch circuits a single common neutral could be shared for both circuits. The bare green EGC is only for fault current while the current carrying neutral is for normal return current and the two are bonded only once in the panel never again. I can only testify of the nec when and where I practiced when a single EGC sufficed and expect its true in your area but where fire and life safety if concerned check with any local authority versus anthhibg posted here me included Im long retired from practice. Ps while conduit can suffice for EG C in limited cases I never liked that practice and especially if non professional electricians were installing. John T long retired EE so no warranty

 

[Ted in NE-OH]

Yes I really mean green ground wire