Two NEC questions

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Hi folks,
After searching on the web and this site, I couldn't find the answer, so I hope you guys can help..

NEC is NEC, and there is not much sense in questioning it. That said, it's always good to know the "why's", the real-life reasons behind one thing or another.

1. What is the rationale behind the dedicated 20A laundry circuit requirement? What kind of equipment in the residential laundry room, aside from the washer/dryer which get their own circuit(s) anyway, may require so much power?

2. Why are the MC support requirements (every 6 ft) are looser than those for AC (every 4.5)? In my experience, AC is a much more robust cable, so why does it (AC) have to be supported more frequently?
 

infinity

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1. What is the rationale behind the dedicated 20A laundry circuit requirement? What kind of equipment in the residential laundry room, aside from the washer/dryer which get their own circuit(s) anyway, may require so much power?

Why do you assume that the laundry area would have more than one circuit?
 

GoldDigger

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But he said that he thought that the washer and dryer would already have a circuit separate from the 20A circuit under discussion. I was addressing that.

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Smart $

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But he said that he thought that the washer and dryer would already have a circuit separate from the 20A circuit under discussion. I was addressing that.

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And add that the NEC does not say the washer cannot be plugged into the laundry branch circuit, IIRC.
 

iwire

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But he said that he thought that the washer and dryer would already have a circuit separate from the 20A circuit under discussion. I was addressing that.

But there is no reason to assume they will be on separate circuits and that was what Rob was addressing.
 

Strathead

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I think the confusion here, or my confusion if not the OP and other answers is, the OP seemed to imply that there should be a circuit for the washer and then the circuit he is referring to is an additional circuit. If this is so, then the answer for the OP is that only one circuit is required in the laundry and that is basically so that a fly by night electrician doesn't provide power for the washer with other recepts.
 
Guys, I'm just an apprentice, so thank you for your patience with me..
An electric dryer will get a separate 30A circuit -- I realize that.
My assumption was that the 20A laundry circuit was meant to be separate from a 15A to 20A circuit that the washer would be plugged into;
Then again, I don't think there is anything in NEC about a dedicated washer circuit.

As far as the AC support, I think I figured out the answer to my own question; AC cable having a denser steel jacket will be heavier per linear foot, hence the need to support it at shorter intervals.
 

Strathead

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Guys, I'm just an apprentice, so thank you for your patience with me..
An electric dryer will get a separate 30A circuit -- I realize that.
My assumption was that the 20A laundry circuit was meant to be separate from a 15A to 20A circuit that the washer would be plugged into;
Then again, I don't think there is anything in NEC about a dedicated washer circuit.

As far as the AC support, I think I figured out the answer to my own question; AC cable having a denser steel jacket will be heavier per linear foot, hence the need to support it at shorter intervals.

You will find a lot of "patience" here. Quotes because I don't consider it patience, I just consider it a main purpose of visiting here. It is a good thing to try and understand the why of the code book, in my opinion. I have always believed that most of us if not all of us violate the NEC intentionally on occasion. It is only with understanding of what the impact of that violation is and extreme difficulty in complying that I do. Anyway, I guessed and answered your laundry portion above.

Regarding the AC support, I don't believe you have it right. GRC, which is much heavier than EMT has a longer distance between straps for example. The earlier answer about the sheath being a rated grounding conductor may have validity, but then I would question why type HCF-MC, which also rates the sheath as a grounding conductor doesn't have the same (smaller) spacing. Honestly I have never worked with AC so I didn't even know there was a spacing difference. I am very glad to come here, because now I will know enough to watch out for it. Sorry I couldn't help you with the actual answer.
 
Strathead, yes -- I refreshed a page after posting my last reply, and sure enough you did indeed understand what I meant and answered it, even before I replied.

Thank you again.

That's my feeling exactly -- if one understands the reasons behind this provision and that, instead of just blindly following the book, that will help making the right choices when the situation is not just black and white..
Glad to be here. Happy, healthy and prosperous New Year to you and everyone else here..
 

don_resqcapt19

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...
My assumption was that the 20A laundry circuit was meant to be separate from a 15A to 20A circuit that the washer would be plugged into;
Then again, I don't think there is anything in NEC about a dedicated washer circuit. ...
You are correct, the code does not prohibit the washer from being supplied by the required 20A laundry circuit.
 

ggunn

PE (Electrical), NABCEP certified
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You will find a lot of "patience" here. Quotes because I don't consider it patience, I just consider it a main purpose of visiting here. It is a good thing to try and understand the why of the code book, in my opinion. I have always believed that most of us if not all of us violate the NEC intentionally on occasion.

But as a PE I would never admit such a thing on a public forum. :D
 

charlie b

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Actually, the homeowner could plug a toaster, a vacuum cleaner, a TV, a fish tank, or a floor lamp into the receptacle that the code makes us put there, and makes us connect to a 20 amp circuit. The code's requirement is for the outlet and the circuit, and it does not have any restrictions on its use. It is there so that the homeowner has the ability to put laundry-related equipment in the space.
 

tom baker

First Chief Moderator
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Hi folks,
After searching on the web and this site, I couldn't find the answer, so I hope you guys can help..

2. Why are the MC support requirements (every 6 ft) are looser than those for AC (every 4.5)? In my experience, AC is a much more robust cable, so why does it (AC) have to be supported more frequently?

MC is a newer product and I was told that is the way the testing and listing was done for support. AC may qualify for 6 feet but it would have to tested and listed to that standard.
 

Strathead

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Location
Ocala, Florida, USA
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Electrician/Estimator/Project Manager/Superintendent
But as a PE I would never admit such a thing on a public forum. :D
That is why I said most of us, because I didn't mean me of course. (plausible deniability) and I use an alias so Childress won't know who I am. :lol::lol::happysad: but mostly:angel:
 
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