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Old 03-03-2014, 02:19 PM   #1
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Metal Conduit Ground Return Path code


Hi all,
I'm new to this forum, I need a bit of advice on an electrical install that I'm helping a neighbor with. Here's what we're stuck on.

My neighbor (Don) is in the organic fruit business, he's setting up a fruit drying operation at his farm. He needs to run a new power supply line to the fruit dryers. There are 6 dryers, each one has a heating element with a blower/circulation fan, they consume 950 watts each. These will be operated on 220 volts. For ease of installation, we plan to use flexible metal conduit. Here's where we have become confused on CODE. I don't know if we will need a 10/2 wire or a 10/3 wire. It has to do with the Ground Return Path code. I'm wondering If it's allowed to simply use the flexible metal conduit for this ground or do we need a 10/3 wire that includes a wire for the ground return path? I read the other day, if it's going to be used for lighting, then we can not use the metal conduit for this ground, if the wire is over 6 foot. These dryers do have a light inside them and the wire will be more then 6 foot from the power line source to the dryers, so I'm not sure how to proceed. We don't want to do an install to find out it won't pass code. I suppose we could just go ahead and use 10/3 that would have a ground return path wire included, but 10/3 is more costly then 10/2, just trying to save a Buck.

Also, are there any codes that restrict us running the metal conduit wire through an internal wall. The wall is covered with laminated paneling on both sides, with no insulation. We plan to hang this conduit wire to the ceiling, then run it about 60 feet to cover the connections to the dryers, so about every 10 feet we would have a junction box that has a rubber insulated cord that drops down to power up each dryer. Also to save on some costs for junction boxes, can we simply hook up 2 dryers to each junction box, so then we'd only need to have 3 junction boxes instead of 6.

Thanks for any help you can provide and thanks for being here!
Bill.

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Old 03-03-2014, 02:49 PM   #2
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Metal Conduit Ground Return Path code


The flex is going to need a grounding conductor. It sounds like you are trying to pull a cable into the flex. It will be much easier to pull individual conductors instead of the cable.

The flex cord to the dryers does not sound like it meets the criteria to use flex cord.

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Old 03-03-2014, 03:46 PM   #3
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Metal Conduit Ground Return Path code


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The flex is going to need a grounding conductor. It sounds like you are trying to pull a cable into the flex. It will be much easier to pull individual conductors instead of the cable.

The flex cord to the dryers does not sound like it meets the criteria to use flex cord.
I'm looking at buying the metal flex conduit with the conductor wires already installed in it. So, what you're telling me is that I would need to use 10/3 and not a 10/2. It does not meet code to use the metal conduit as the Ground Return Path?

Not sure what you mean by this "The flex cord to the dryers does not sound like it meets the criteria to use flex cord"

Here's what I do know. These dryers were purchased second hand. The cord that connects them to the power source has been cut off, but what's left of those cords are 14/3 rubber insulated type electrical cord. I can only assume this type of cord that delivers power the dryers was to code? If it is, then we plan to use the same type of rubber cord on them again. I'm not real sure if that cord should be ran through flexible conduit as well, I think you're telling me, it's not necessary? I wish the owner had the funds to just hire a certified electrician to do this work for him, but he says he's running on very little $ to get it done. He knows I do understand a bit about these things, that's why he asked for my help, because he has no clue at all.

Thanks much for your help. but I'm still a little bit unsure....
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Old 03-03-2014, 03:55 PM   #4
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Metal Conduit Ground Return Path code


When you said flex conduit I thought you were talking about Greenfield where the conductors are puller in. Are you buying MC or AC cable?

The flex cord may not have been correct to start with.

950 watts at 240 is less than 4 amps each. You do not need #10.
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Old 03-03-2014, 03:57 PM   #5
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Metal Conduit Ground Return Path code


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Originally Posted by yogidog View Post
I'm looking at buying the metal flex conduit with the conductor wires already installed in it. So, what you're telling me is that I would need to use 10/3 and not a 10/2. It does not meet code to use the metal conduit as the Ground Return Path?
That's not typically called "flex", it's MC cable or AC cable depending on the specific type. It always includes a grounding conductor. 10/2 MC has white, black, and ground, and 10/3 MC has red, white, black, and ground. This can be used for your application if it is not exposed to moisture or physical damage.

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Not sure what you mean by this "The flex cord to the dryers does not sound like it meets the criteria to use flex cord"

Here's what I do know. These dryers were purchased second hand. The cord that connects them to the power source has been cut off, but what's left of those cords are 14/3 rubber insulated type electrical cord. I can only assume this type of cord that delivers power the dryers was to code?
Rubber cord (SO, SJOOW, etc) is only allowed in a few specific applications. This doesn't initially appear to be one of them. It seems likely that the dryers used to have plugs on them, rather than being hard-wired. See if the manufacturer's instructions say how they are supposed to be installed.

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If it is, then we plan to use the same type of rubber cord on them again. I'm not real sure if that cord should be ran through flexible conduit as well, I think you're telling me, it's not necessary?
Well you definitely can't run rubber cord through conduit. If these are going to be hard-wired, it would be best to run the MC cable directly into the unit, assuming it has provisions for that. Otherwise if it has a rubber cord on the unit, either put a plug on it and mount a receptacle nearby (probably the best option), or run the rubber cord to a J-box nearby to change over to MC cable.

Edit: It looks like you are intending to wire all 6 of these on one circuit, hence the #10 wire. The manufacturer's instructions will specify a maximum circuit ampacity, and I would bet it's much less than 30A. You will probably need to use multiple smaller circuits. The upside is that you will be able to use smaller wire. Three 15A circuits with two dryers each on #14 wire will probably do fine.
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Last edited by mpoulton; 03-03-2014 at 04:01 PM.
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Old 03-03-2014, 04:01 PM   #6
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Metal Conduit Ground Return Path code


10/2 wire should still have a ground in it. 10/3 will only be needed if the dryers require it.
If you are using rubber cabtire then you need 10/3 as they count the wires different in rubber cords.
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Old 03-03-2014, 04:02 PM   #7
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It would be very helpful to post the manufacturer and model number of the dryers, and preferably some photos of them too. That way we can help determine how they are supposed to be wired.
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Old 03-03-2014, 04:04 PM   #8
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If the units are hard wired you are going to need a disconnect for each unit unless within sight of the panel.
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Old 03-03-2014, 05:00 PM   #9
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I'm going to completely skip out on saying this type of work isn't allowed to be done by a neighbor...
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Old 03-03-2014, 07:09 PM   #10
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I'm going to completely skip out on saying this type of work isn't allowed to be done by a neighbor...
Especially a neighbor who is clearly not qualified to be doing electrical work for others.
Sorry. It's just the way it is.
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Old 03-04-2014, 08:01 AM   #11
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Metal Conduit Ground Return Path code


Thanks to all who gave advice. We actually got all my questions answered by an electrician at Homedepot. He was very helpful and seemed to know his stuff. Anyway, I don't plan to be the one doing this work, my neighbor will do it. He just needed to get lined out on the proper material's and codes.

Thanks again,
Bill.
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Old 03-04-2014, 08:07 AM   #12
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Metal Conduit Ground Return Path code


Quote:
Originally Posted by yogidog
Thanks to all who gave advice. We actually got all my questions answered by an electrician at Homedepot. He was very helpful and seemed to know his stuff. Anyway, I don't plan to be the one doing this work, my neighbor will do it. He just needed to get lined out on the proper material's and codes. Thanks again, Bill.
Is this post aimed at easing professional minds? I can't imagine a more uncomforting scenario.
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Old 03-04-2014, 08:36 AM   #13
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electrician at Homedepot.
I suppose there's first time for everything. What did he tell you?
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Old 03-04-2014, 01:24 PM   #14
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Metal Conduit Ground Return Path code


I have to say, I have encountered a couple of decent guys at Lowes and HD. A couple mind you.
For the most part the advice that I hear given out at those places is sketchy at best and downright dangerous at worst.
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Old 03-04-2014, 01:46 PM   #15
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I finally got hold of my electrician friend, he's been on vacation. That's why I came here for advice, he was unreachable. Anyway, this morning I ran everything by my electrician friend as to what I'm doing and all the codes and such. Seems the guy at Home depot was right on it. I'm very confident now, that I have all the proper info to proceed. So, we'll get the needed permit and hook things up, then call in the inspector. I think all will be fine.

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