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A few practical questions: From conceptual circuit to having to actually install

A few practical questions: From conceptual circuit to having to actually install

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  #1  
Old 06-11-17, 08:54 AM
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A few practical questions: From conceptual circuit to having to actually install

I have a wonderful new barn / shop that I recently built and will be adding several brach circuits. I have some basic sketches of where the circuits run, how much load is on each, etc.

Now I am starting to plan the actual install and given where I can actually run things it brings up some implementation questions. At least one questions is clearly my OCD kicking in, but I am hoping when I am done, that an experienced electrician would look at what was done and think it was well done.

For context, all wiring is going to be THHN run through EMT conduit.

The "conceptual" circuit I want to run is a basic lighting circuit with a switch in the middle. Like this:

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Seems simple enough. However, where the light is actually located a short distance from where the main conduit run is. So the circuit I need to wire would look more like this:

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However, I have a few question about doing this.

Question A: Is a "tee" OK?

From the first "conceptual" circuit diagram, clearly it is fine to attach a light fixture at the junction box along the main run. However, as shown in the second diagram, if I have to "tee" off and run a short distance, to a second junction box, how far can I extend that or is that even to code?

Question B: What color wire should I use?

The switch is also not located right along the main conduit path and needs to be a short distance from that main run. Here, I really only need the red 'hot' wire, but my understanding of code now is that neutral needs to be present in a junction box, even if it just currently contains a switch (and ground should be run to ground the box. So, given this extension to the switch, I will run 4 wires, the hot to and from (thats 2) the neutral and the ground. In the drawing I have shown red, black, white and green. If I do that, then part of the hot leg that has been on red wire, now gets connected to black to the switch, then back to red to run further down the line. I could just run two red out to the switch, so that all connections along that wire are same color, but then I am running two reds down the conduit and it is important to know which side is line and which side is load. I could mark one of the red lines. So, running 4 wires, should I run 2 red, white and green OR black, red, white and green?

If you were to just take a conceptual drawing where you draw the electrical cable running between each light and you were not worried about saving actual wire, the above circuit would look like this:

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Question C: Looping out to a box VS a tee to a box. What to do?

This is really a follow up to question A. When installing a circuit like the one I am asking about, what part of NEC or just basic wiring knowledge help determine if you wire things like the second diagram or the third diagram (what I am calling "tee" vs. "loop")?

Thank you for any replies that can help me fill in the gaps in my knowledge. I am a naturally curious person who always wants to completely understand how something works, not just be told how to do something. I have done a ton of searching, trying to find the answers to my questions, but I wasn't really able to find anything to address these specific question.

Thanks again for any help.
Matt
 
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  #2  
Old 06-11-17, 09:47 AM
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Question A: Is a "tee" OK?
Yes, but your "Tee" should be a junction box as you mention. There is no limit of distance of switch legs (or any other wires for that matter) so that is not an issue.

Question B: What color wire should I use?
Neutral wires can be white or gray, with or without colored stripes
Grounds can only be green, bare, or green with a yellow stripe
Ungrounded wires (Hots/ Switch legs) can be any color other then the ones listed above.
I would suggest using an odd color for the switch leg(s)

Question C: Looping out to a box VS a tee to a box. What to do?
There is really point of doing what you show in picture C and it is a waste of wire. No electrician would do that.

A couple of other notes:
If you are using EMT and the proper fittings, and the conduit is properly connected and installed, you do not need to install a ground wire. EMT is an approved grounding path. You will still need to connect a ground wire at the lights to the steel box using a proper ground screw if present. You can still install a ground if you choose. Switches installed to a grounded metal box are not required to be separately grounded.

Also I have made a small change to your diagram. I connected the red (switchleg) to the black feeding the lights in the box above the switch. There is no reason to run it to the first light:

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Last edited by Tolyn Ironhand; 06-11-17 at 07:45 PM. Reason: typo
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Old 06-11-17, 01:41 PM
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Thanks so much for the great info. Helps a ton.

Right, totally makes sense that you don't need to run the switching leg out to the end. That is great. It also solves my OCD wire color issues since I will use red all the way to the switch then black from the switch to tie back into the rest of the black feeding the lights. All nice and clean that way.

Also glad to hear that no one would do what is shown in the 3rd picture. That is just more of the direct translation of drawing the rough layout of where I am going to run lines. Anyway, thanks for confirming it is ridiculous.
 
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Old 06-12-17, 08:54 AM
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I would recommend getting an electrical permit and having your work inspected. That is be best way to be sure you have done everything properly and safely.

Also you can take pictures of the area, then go meet with the electrical inspector ahead of time (they have certain hours for this), then go over what you plan to do. The inspector can advise you against doing things which would not pass inspection BEFORE you go to the store and buy the materials/do the work.

Be aware of GFCI requirements, especially if there will be animals in your barn.
 
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Old 06-12-17, 11:19 AM
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but my understanding of code now is that neutral needs to be present in a junction box
If you're using cables like Romex where adding a neutral later is impractical, then you need to install the neutral up front. If you're using a conduit system where a neutral can later be pulled, you only need to provision conduit sized to allow a neutral to be added in the future if it is ever needed.
 
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Old 06-28-17, 12:05 PM
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Thank you for the advice. I have applied for and received the permit. It is posted on site.

Smart thing to allow for a conversation and review before doing the work, I will totally check into this.

Cheers!
 
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Old 06-28-17, 05:23 PM
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Everything I have seen I agree with the others but you don't need to run a green for the ground because the emt is a legal ground so you can buy green pig tails with a green screw that you screw right to the back of the metal handy box or 4square it will save you time and money and the last thing is why are you using emt because if it's wood frame structure you can save money, time and labor using romex and if it's let's say block then use pvc it will again save you money, time, and labor or use mc cable to save a little money but lots of time and labor. Emt is the last option If I were you.
 
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