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Old 07-28-2018, 01:54 AM   #21
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I have a customer that refurbishes Prevost motor coaches. You'd better believe they pull full amps with the air conditioners running without the bus engine on, and you'd better believe they run constantly in the shop in the middle of summer. 50 amp breaker @ .8 breaker loading, 200', in conduit, shop is 208/120 ----> #4 coppah
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Old 07-28-2018, 03:30 AM   #22
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I have a customer that refurbishes Prevost motor coaches. You'd better believe they pull full amps with the air conditioners running without the bus engine on, and you'd better believe they run constantly in the shop in the middle of summer. 50 amp breaker @ .8 breaker loading, 200', in conduit, shop is 208/120 ----> #4 coppah
You're describing a commercial firm.

In my town, any residence caught doing what you're proposing would have the sheriff showing up ultra-fast. Around here, you can't even have such an RV outside. You have to build a custom garage for it.

The OP wants to know what would be regular residential standards.
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Old 07-28-2018, 07:03 AM   #23
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Here's an example - can someone tell me what wire you would install for a new hot tub, 60 amp, 240v, 200 ft run? From what I can see, by the Code, #4 (copper) wire isn't big enough. What would you actually run?
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The calculator says #4 which would be a 2.88% voltage drop.
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So far no one has answered the original question, regarding the example given.
What would you run??
Actually I think @gpop answered it, I think your calculation was off and everybody's happy with #4.

I agree with @readydave8 and @cabletie, the inspector seems well intentioned but must pull their head out of their butt with respect to the informational notes. Even aside from the bit that @cabletie posted about the informational note, even the language in the note is free of shall's, must's, etc.

Now I am with the OP that if it's a receptacle, I do absolutely no speculating about the load they tell me will be on that receptacle. My goal is that my customers can rest assured that between when I put it in and when the building is torn down, if someone puts in a properly wired appliance with the proper plug, and they don't force a square peg in a round hole, it's going to work as it should.
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Old 07-28-2018, 09:25 AM   #24
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I believe fire pumps is the only area of the nec that has voltage drop parameters.
That is surprising to me as the CEC is very clear on voltage drop allowances.

We have codes and tables for calculating it. Iíve even had inspectors check it on long runs.
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Old 07-28-2018, 12:05 PM   #25
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Here's an example - can someone tell me what wire you would install for a new hot tub, 60 amp, 240v, 200 ft run? From what I can see, by the Code, #4 (copper) wire isn't big enough. What would you actually run?
The 200' run would be unusual inside, if I ran into that would probably run #2 aluminum
And switch over to #6 before tub (probably at dissconnect)

But the 60 amps is still confusing me, that tub may pull 32 and manufacturor still be asking for 60 amp circuit
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Old 07-28-2018, 12:22 PM   #26
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I would run a 6-3 romex and call it good. Commercial application I may bump it to 4 but I doubt it.
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Old 07-28-2018, 12:34 PM   #27
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I would run a 6-3 romex and call it good. Commercial application I may bump it to 4 but I doubt it.
By code you can not use a #6 for 60amps as it would be under the 60c restriction for conduit/direct burial. Or am i reading that wrong.
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Old 07-28-2018, 06:45 PM   #28
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Hot tubs and RV receptacles get (usually) very occasional demand.

I'd go with a 5% voltage drop and not sweat it.

The heaters in a hot tub won't care, and the pump can handle 5%, no sweat.

You're not wasting that much power, and the conductors are not going to cook off.

The actual draw of a stored RV at someone's residence is trivial until its occupied, something that most suburbs won't permit. You can store it there, sometimes, but you're not supposed to be living out of it.

End of problem.

You need to get out of Cali and travel the south a little.

Many around here live in RVs in the yards of relatives.
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Old 07-28-2018, 06:53 PM   #29
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You need to get out of Cali and travel the south a little.

Many around here live in RVs in the yards of relatives.
NO.... He and I can stay in Cali, the weirdos can leave. Damn... This would be the least populated state.
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Old 07-28-2018, 06:57 PM   #30
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NO.... He and I can stay in Cali, the weirdos can leave. Damn... This would be the least populated state.
Then you guys better get something going to push them due west or due south, just don't let them crazy things head east by any means.
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Old 07-28-2018, 07:00 PM   #31
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Then you guys better get something going to push them due west or due south, just don't let them crazy things head east by any means.
Ever see that John Candy flick "Wagons East"? From everyone I know that moves out of Cali, they go to the following places:

Texas
North Carolina
Oregon
Washington

I'll put out a memo to head to Virginia... Isn't that where your at Mech?
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Old 07-28-2018, 07:36 PM   #32
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Hot tubs and RV receptacles get (usually) very occasional demand.

I'd go with a 5% voltage drop and not sweat it.

The heaters in a hot tub won't care, and the pump can handle 5%, no sweat.

You're not wasting that much power, and the conductors are not going to cook off.

The actual draw of a stored RV at someone's residence is trivial until its occupied, something that most suburbs won't permit. You can store it there, sometimes, but you're not supposed to be living out of it.

End of problem.

Another example I could have given was an RV receptacle circuit that we just installed. Client wants to park his RV in back of his business, so it was basically a residential job in a commercial setting. Two electricians before us gave him a bid for the job based on running #10 wire for his 125v, 30a circuit.

From panel to receptacle it was at least 165 ft. Calculation says #4 Cu wire. We ran #6. (Again - what would you run??)

As we finished the job, client asked if I'd pick up 85 ft of #10 SJ so he can make an extension cord to add to the 30 ft cable in his RV because he intends to park it down the fence line instead of up against his shop.

Just the voltage drop in the 85 ft to the receptacle would have been 10% (12.3v) if someone ran #10 wire. Then the guy adds another 115 ft after you leave, he's got an 18.6v drop. And there's no telling what he expects to plug in and use in the RV, maybe just the A/C, maybe not.

I get the idea there are a lot of guys that would be just fine with that.
If I was the client and figured out that I had <100v available because my electrical contractor didn't bother to consider voltage drop, I think I'd be pissed off.

I'm feeling kind of alone here though...
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Old 07-28-2018, 07:48 PM   #33
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Another example I could have given was an RV receptacle circuit that we just installed. Client wants to park his RV in back of his business, so it was basically a residential job in a commercial setting. Two electricians before us gave him a bid for the job based on running #10 wire for his 125v, 30a circuit.

From panel to receptacle it was at least 165 ft. Calculation says #4 Cu wire. We ran #6. (Again - what would you run??)

As we finished the job, client asked if I'd pick up 85 ft of #10 SJ so he can make an extension cord to add to the 30 ft cable in his RV because he intends to park it down the fence line instead of up against his shop.

Just the voltage drop in the 85 ft to the receptacle would have been 10% (12.3v) if someone ran #10 wire. Then the guy adds another 115 ft after you leave, he's got an 18.6v drop. And there's no telling what he expects to plug in and use in the RV, maybe just the A/C, maybe not.

I get the idea there are a lot of guys that would be just fine with that.
If I was the client and figured out that I had <100v available because my electrical contractor didn't bother to consider voltage drop, I think I'd be pissed off.

I'm feeling kind of alone here though...
I would use a #6 copper and except a 3.65 drop knowing that a rv ac unit has a hard start installed as standard. (we redneck so we know what relatives need in them there rv's).

What calculator are you using?
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Old 07-28-2018, 07:49 PM   #34
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NO.... He and I can stay in Cali, the weirdos can leave. Damn... This would be the least populated state.
A few years ago, when I lived north of Portland, Oregon I thought everyone in California was moving north up the coast.
Then I got to Idaho and realized those were just the few that didn't know the most direct route to Boise.
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Old 07-28-2018, 07:56 PM   #35
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@xnuke This is the difference between residential and commercial/industrial work.

Generally in commercial and industrial, your values of the end product or usage are known, calculated and accounted for. So the right size conduit, wire, devices, etc. are installed. All of this because it has been specifically engineered.

Residential, well that's a total crap shoot....

Electrician: "What are you going to use this for?"

HO: "Maybe this... Maybe that..."

Electrician: "I need to know what will be used so I can correctly size it"

HO: "Can't you just install some big wire and a big fuse so I can use whatever?"

Electrician:


Don't worry about what other guys are doing so much. If you can sell it as an upgraded installation, as you seem to have done in the case of the RV receptacle, then you'll be seen as more knowledgeable to your clients. The other EC's may not agree with your thinking, but your cashing the checks they didn't get.

I tend to personally err on the side of caution with my installations, as I have seen to many homes completely inadequately wired for actual usage.

Does it cost more? Yes

Does it take a little longer? Yes

Am I loosing money? No

Is the customer happy? Yes
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Old 07-28-2018, 08:10 PM   #36
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What calculator are you using?

I've googled several to compare answers and don't see a difference between them, but I kept a shortcut to one that I use when I want a quick answer at a jobsite or something. I'd include the link, but evidently I can't until I've made 3 more posts. It's not an app, just a website.

If I'm at my desk though, like when I made the previous post, I use the formula and Code book (chpt 9).
VD = (2 x K x I x L) / Cmils

K = 12.9 Cu or 21.2 Al
I = circuit voltage
L = circuit length one way
Am I doing something differently than everyone else??
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Old 07-28-2018, 08:31 PM   #37
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@xnuke This is the difference between residential and commercial/industrial work.

Generally in commercial and industrial, your values of the end product or usage are known, calculated and accounted for. So the right size conduit, wire, devices, etc. are installed. All of this because it has been specifically engineered.

Thanks for your post. You nailed it on the conversation with a HO.

I'm getting an EC company started, along with a partner, after spending nearly 15 years in Industrial maintenance working for major Pulp & Paper companies. Most of that time was spent as an electrical supervisor and/or planner.

You're right, and I just hadn't really thought about it. All of my background has me conditioned to do everything to the letter of the law or better. Reliability required for a multi-million dollar paper machine is a whole different level than my garage outlets.

I still have a hard time taking shortcuts.
I have a hard time standing on the top of a 6' ladder too though.
Maybe getting out of Pulp & Paper industrial settings will get me past both things. (I kinda hope not...)
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Old 07-28-2018, 08:37 PM   #38
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I think it was French who said sometimes you have to throw out the codebook, and like it says in the book it isn't a design manual, not to mention it is a set of minimum rules.

Most of us have been in the game long enough to know what works, what doesn't, how people use things, etc...

It isn't about cutting corners, it is about doing the best installation for the job. When that outcome is an unknown, then you can choose to do a minimum, medium, or prepare for worst case.

Whether that is wrong or a shortcut, that may all be in the eye of the beholder. The beholder is the end user, your customer. As long as the installation is "Safe", there is a lot of wiggle room.
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Old 07-28-2018, 08:47 PM   #39
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Ever see that John Candy flick "Wagons East"? From everyone I know that moves out of Cali, they go to the following places:

Texas
North Carolina
Oregon
Washington

I'll put out a memo to head to Virginia... Isn't that where your at Mech?
I'm telling ya 'don't send us no liberal-progressive types' it might kick off a civil war!
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Old 07-30-2018, 09:04 AM   #40
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By code you can not use a #6 for 60amps as it would be under the 60c restriction for conduit/direct burial. Or am i reading that wrong.
You are probably right, but it is what I would do anyway. Although on second thought on a run that long I may run 2-4 Alum SE cable. That would save $400 or more.
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