# Interpreting The Instruction Manual



## ColbyL (Jun 21, 2019)

So as per my last threads, I have been put in charge of a project I am not qualified for and rather than wait for instructions to be handed down or a mistake to appear later after things have been drywalled, I am taking the initiative to figure things out when something sounds wrong. 

So I am working on a 4 floor commercial/residential combo building. First floor lobby/parkade. second and third are commercial offices. Fourth floor is residences. 

In this building on the roof, they have three Samsung cooling units. This is the instruction manual for the outdoor units


https://s3.amazonaws.com/samsung-files/Tech_Files/CAC/Outdoor+Units/Installation+Manuals/AC0+09+12+BXADCHAA_Inst+Manual_DB68-11179A-00_210917_ENGLISH.pdf


Specifically, the 36,000 BTU and the 24,000 BTU versions. 
Here's the manual for the indoor units that I was given. 


https://s3.amazonaws.com/samsung-files/Tech_Files/CAC/AC0_BNHDCHAA_Duct+S/Submittals/AC036BNHDCH+(CNH36HDB)_Submittal_CAC+Single+Zone_Duct+S_02072022.pdf



I thought I had figured out everything in regards to these stupid things, but they keep coming back. My current installation includes a 10/2 to the two larger units for Homeruns and a 12/2 for the smaller unit homerun. Then a 14/3 from each cooling unit, to the indoor unit fan coil.

The problem is that I called the owner of my company up today to ask for material and we were discussing things when all of a sudden he says something that throws a wrench in the whole thing. He says "all these devices will say in the front that you can install them in #14, but then in the back of the manual they say that in a commercial application they have to be run in #12." Can someone clarify if that's right? Where this is coming from and weather it applies in this situation?


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## LGLS (Nov 10, 2007)

Not your zoo, not your monkeys. Owner says he knows better, so if it’s wrong it’s on him.


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## Dennis Alwon (May 9, 2009)

Could it be the difference between MC cable and nm cable. NM is rated at 60C where mc can be used at 75C


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## ColbyL (Jun 21, 2019)

I know I can use that as a get out of jail free card, but I hate doing it. I consider it my last resort. The way I see it, just because I can tell him "You dumped this on me" doesn't mean I should use it as an excuse to avoid the problem. 

I'm surprised this doesn't sound familiar to you. The way he was talking he said "Only the lights get #14. In commercial, everything else gets #12." Is that just a personal standard then?

I'm not a commercial electrician really. My experience is all woodframe residential.


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## kb1jb1 (Nov 11, 2017)

This is something I hate about foreign made equipment. The manuals are not written to what us old timers are use to. This looks like a simple ductless mini split system. 24 amps to the outside unit with a max circuit breaker amps of 35. The inside unit gets it power from the outside unit via 3 wire power/control cable. The old discussion is if that 3 wire cable is HVAC control work or electrician power wiring. Here we leave that interconnection up to the HVAC guys because they have an approved " mini split" cable. We would have to go to the HVAC supply house for it. What does the HVAC contractor say? Or is the building owner or contractor using all inexperienced subs? I am not saying the subs are not smart or low end. They might be in a learning stage. We all have been there.


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## ColbyL (Jun 21, 2019)

The HVAC guys supplied and installed a 16/2 thermostat control cable. We're responsible for all power wiring.


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## kb1jb1 (Nov 11, 2017)

The full manual finally came up and I repeat my comment about foreign written instructions. They are not written with our way of doing things. It said single phase but has 3 power wires. I think they meant 2 power wires and an equipment ground. It also says if no equipment ground is present to drive ground rods. That's one of the worst things you could do. Sometimes men throw out instructions and wire it the way we should. That is where experience comes in. They probably want #12 for voltage drop if there is a long run. It seemed to imply no more than a 2% difference.


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## MikeFL (Apr 16, 2016)

ColbyL said:


> ...The problem is that I called* the owner of my company* up today to ask for material and we were discussing things when all of a sudden* he says* something that throws a wrench in the whole thing. He says "all these devices will say in the front that you can install them in #14, but then in the back of the manual they say that in a commercial application *they have to be run in #12*." Can someone clarify if that's right? Where this is coming from and weather it applies in this situation?


Sounds like you have two choices.
Run it in #12 or find another job.
Why would you ask us to trump your boss? 
I can see if safety were an issue. He's saying upsize the wire which he's paying for. Be a good employee and do as instructed.


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## ColbyL (Jun 21, 2019)

The point is that I understand why it happened in the first place. The boss says do it because of reasons and I would at least like to understand those reasons. 

Thank you Kb1. A tight voltage drop makes sense. 

Also, the boss never said I had to redo it. We were talking about the material that I ordered and he asked why I needed #14 white. Everything in the building should be #12. So I told him it was for the fans that say in the manual to run it as 14/3. Then he brought up the #12 thing. 

So I'm definitely running the piped section as #12, But I figure I can ask him if he wants me to redo the loomex in #12 or just leave it as the instruction manual said to run it.


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## wcord (Jan 23, 2011)

kb1jb1 said:


> The full manual finally came up and I repeat my comment about foreign written instructions. They are not written with our way of doing things. It said single phase but has 3 power wires. I think they meant 2 power wires and an equipment ground. It also says if no equipment ground is present to drive ground rods. That's one of the worst things you could do. Sometimes men throw out instructions and wire it the way we should. That is where experience comes in. They probably want #12 for voltage drop if there is a long run. It seemed to imply no more than a 2% difference.


The third wire is a communication wire.
Don't know about the states, but up here, we don't count the ground wire (except for cab tire) in the cable assembly


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## ColbyL (Jun 21, 2019)

Would be lovely if I understood how to install that communication wire. As far as I can tell, the cooling units and the indoor fan units only have two terminals for 1-phase line to line voltage.


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## LGLS (Nov 10, 2007)

ColbyL said:


> The point is that I understand why it happened in the first place. The boss says do it because of reasons and I would at least like to understand those reasons.
> 
> Thank you Kb1. A tight voltage drop makes sense.
> 
> ...


YMMV but you’re on a commercial job, leave the #14 at the shop or in the truck.


ColbyL said:


> I know I can use that as a get out of jail free card, but I hate doing it. I consider it my last resort. The way I see it, just because I can tell him "You dumped this on me" doesn't mean I should use it as an excuse to avoid the problem.
> 
> I'm surprised this doesn't sound familiar to you. The way he was talking he said "Only the lights get #14. In commercial, everything else gets #12." Is that just a personal standard then?
> 
> I'm not a commercial electrician really. My experience is all woodframe residential.


what your boss is saying is don’t worry about pinching pennies, wire the lights with number 14 only and leave it at that. Everything else he considers power, and wants it in 12 minimum. This is pretty much a standard on many commercial jobs that come with specifications. It is often times repeated on the print in the construction notes.

in the grand scheme of things, at the end of the day or rather, at the end of this job – your boss would rather see the inspection pass with flying colors and no issues, then to realize what little savings could have been had by running number 14 wherever possible. Inspectors tend to “glaze over“ minor code in fractions when they can see it’s clearly obvious the contractor wasn’t trying to save $.10 here, five cents there, etc. etc.

here’s another example, if you have a bank of six switches, don’t gang six gem boxes together and Collett a day. Order a six gang roughhouse box and the raised cover, tons of space, a lot quicker and a lot neater. And any number of people in multiple other trades buzzing through the site over the months carrying ladders, acetylene tanks, bundles of cable and conduit on their shoulder banging into things during the rough stage won’t cause a six gang roughhouse box to disintegrate into little bits.


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## ColbyL (Jun 21, 2019)

Thank you. That makes a lot more sense.


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## cdslotz (Jun 10, 2008)

ColbyL said:


> So as per my last threads, I have been put in charge of a project I am not qualified for and rather than wait for instructions to be handed down or a mistake to appear later after things have been drywalled, I am taking the initiative to figure things out when something sounds wrong.
> 
> So I am working on a 4 floor commercial/residential combo building. First floor lobby/parkade. second and third are commercial offices. Fourth floor is residences.
> 
> ...


What do the specs say about using #14?


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## emtnut (Mar 1, 2015)

Generally in commercial, #14 is never used. Min is #12. This place may or may not have that spec, but any place I know of is #12 whether needed or not.

Plan B ... do what the guy signing your cheques says


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## ColbyL (Jun 21, 2019)

emtnut said:


> Generally in commercial, #14 is never used. Min is #12. This place may or may not have that spec, but any place I know of is #12 whether needed or not.
> 
> Plan B ... do what the guy signing your cheques says


Yup, that's what my boss said. Is LGLS's response to that not complete in some way? Is there a reason for that that hasn't been stated yet? So far we have 
1) It was probably in the construction notes
2) Makes inspection easier
3) Volt-drop is tight in the instruction manual.


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## LGLS (Nov 10, 2007)

ColbyL said:


> Yup, that's what my boss said. Is LGLS's response to that not complete in some way? Is there a reason for that that hasn't been stated yet? So far we have
> 1) It was probably in the construction notes
> 2) Makes inspection easier
> 3) Volt-drop is tight in the instruction manual.


There’s a nuance here, I sort of messaging that you’re probably unaware of seeing as you’re going at this job alone, and you are not hooked up with an experienced journeyman who has been through this time and time and time again.

you generally just don’t ever see 14 gauge wire on a commercial job. I realize the top floor of this place is residential, but set that aside for a moment. Just about all your wiring is going to be 12 gauge or better. Leave the white coils of NM and the spools of number 14 off the site. You don’t want that stuff to get mistakenly mixed up.

In New York City number 12 is the smallest gauge you go. The only exception are fixture whips, And although I haven’t checked them lately, the port authority, schools construction Authority, MTA, Long Island rail Road, all the authorities won’t even allow number smaller than number 12 inside of fixture whip. Can’t even use 3/8 fixture whips in those places either.

And this isn’t about current carrying capacity either, it has nothing to do with it. It’s more about this sheer physical strength, 12 gauge wire over 14. After a few years of working in the commercial and industrial sector, you’re going to look at solid number 14 Romax in your house and think to yourself “how could this possibly carry 1800 W?”


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## kb1jb1 (Nov 11, 2017)

wcord said:


> The third wire is a communication wire.
> Don't know about the states, but up here, we don't count the ground wire (except for cab tire) in the cable assembly


That is what I thought, a communication wire but after I downloaded the instruction manual it showed a separate two wire control. Basically the 30 amp power wires to the outside unit. Then terminals for two #14 wires to the indoor unit plus 2 #16 wires for control to the indoor unit. I think the instruction manual was counting the equipment ground as a power wire. Reading the instructions, I can see how the OP got confused. Every mini split I hooked up only had a three wire control. This one has two wire control plus two wire power.


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## kb1jb1 (Nov 11, 2017)

LGLS said:


> There’s a nuance here, I sort of messaging that you’re probably unaware of seeing as you’re going at this job alone, and you are not hooked up with an experienced journeyman who has been through this time and time and time again.
> 
> you generally just don’t ever see 14 gauge wire on a commercial job. I realize the top floor of this place is residential, but set that aside for a moment. Just about all your wiring is going to be 12 gauge or better. Leave the white coils of NM and the spools of number 14 off the site. You don’t want that stuff to get mistakenly mixed up.
> 
> ...


I have seen #14 in commercial / industrial applications many times. Controls and fire alarms. The problem with much of the newer equipment is that they make the terminals too small for #12 wire. The minimum #12 size wire is only a requirement in certain areas and these units are made for world wide use. If the indoor unit only requires 1 amp then in most areas you can use the #14. The instructions are very specific about voltage differences between the incoming power and the power to the indoor unit. No more than 2%, if I am reading it right.


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## ColbyL (Jun 21, 2019)

Very interesting. Would've been lovely if one of the two foreman's who have been answering questions for me had told me about all of this.

The owner of the company did say lighting could be #14. So I've got that.

KB1, Even when I opened up the devices I only saw two terminals for the outdoor unit -> indoor unit. Having started this thread, I'm starting to think that I need to check the model number of those indoor units myself. I get the feeling that they gave me the instructions for the wrong units.

But yes, this is how HVAC told me to wire it. They even phoned up a samsung cooling unit specialist over the matter.


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## BleedingLungsMurphy (10 mo ago)

ColbyL said:


> commercial application they have to be run in #12


#12 copper is the minimum for 15 amp home runs in commercial applications. See local building codes because it's not in the CEC.



kb1jb1 said:


> I have seen #14 in commercial / industrial applications many times. *Controls and fire alarms*


Fire alarms and controls have different building code requirements. The main fire alarm panel is fed with #12.



ColbyL said:


> Can someone clarify if that's right?


If it's on the nameplate from the manufacturer it's probably right. I don't think anyone here will have any higher authority than the people who designed and manufactured the product.

How much money are you trying to save your boss by running #14 vs #12?


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## wiz1997 (Mar 30, 2021)

So the #10 is correct but the #14 to the other parts, he wants in #12.

Remember the NEC and often, the equipment manufacture's requirements, on wire size are minimums.

You can increase the wire size but not the overcurrent protection.


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## kb1jb1 (Nov 11, 2017)

BleedingLungsMurphy said:


> #12 copper is the minimum for 15 amp home runs in commercial applications. See local building codes because it's not in the CEC.
> 
> 
> Fire alarms and controls have different building code requirements. The main fire alarm panel is fed with #12.
> ...


I have to watch what country. The OP is Canada so I assume you have the #12 requirement. The US does not have that. Some local jurisdictions added it where the State approves the change. I don't keep #14 on the truck because of space limitations. I have limited space of two milk crates for building wire. I have to check the 2020 NEC to see if there are any changes.


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## ColbyL (Jun 21, 2019)

Can someone tell me how to look up the local building code. I tried typing in Local building code Maple Ridge and it sent me to a page to register for an inspection.

EDIT. Nevermind, found the building code. Trying to navigate it now.


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## readydave8 (Sep 20, 2009)

To repeat what others have said, NEC does not prohibit #14 in commercial 

And I agree not desirable and may not be allowed in specs


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## wiz1997 (Mar 30, 2021)

ColbyL said:


> Can someone tell me how to look up the local building code. I tried typing in Local building code Maple Ridge and it sent me to a page to register for an inspection.



You need to be more specific, just your town may not be enough.

City, State, the words building codes.

Good luck wading through city government website.

Might be easier to go to the permitting office and ask for the city's electrical code.

I know at one time, when our city controlled electrician licensing, we had to know City codes along with the NEC for testing purposes.

Had to purchase the City Electrical Code book.


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## emtnut (Mar 1, 2015)

BleedingLungsMurphy said:


> #12 copper is the minimum for 15 amp home runs in commercial applications. *See local building codes *because it's not in the CEC.


LoL 🤣


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## pokeytwo (Dec 6, 2015)

#12 in commercial makes sense when one considers the distance usually found from panels to points of use.


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## ColbyL (Jun 21, 2019)

pokeytwo said:


> #12 in commercial makes sense when one considers the distance usually found from panels to points of use.


Yea, I've thought about it and weather or not it's in the building code, I don't know, but that's probably the reason given that about six panels are spread out over the same area in the residential area. Whereas, I have one panel doing the whole floor in the commercial area.


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## Almost Retired (Sep 14, 2021)

there is a 3% Vdrop for #12 at 16 amps (80% load for 20A breaker) at 65ft
there is a 3% Vdrop for #12 at 12 amps (80% load for 15A breaker) at 86ft


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## ColbyL (Jun 21, 2019)

Honestly, given what you're saying, the thing I'm most worried about is the lights. That hallway circuit goes everywhere with about 10+ lights on the circuit. Some things are switched, some things are night lights. The exit signs and the EM pack also are on that circuit. I have almost no doubt I'm over a 3% volt drop. But I suppose it doesn't matter for LED lights. I think there's even a bathroom fan on the damned thing. 

But this is the circuit the owner of the company told me to run in #14. So whatever.


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## Viggmundir (Sep 13, 2019)

ColbyL said:


> Yea, I've thought about it and weather or not it's in the building code, I don't know, but that's probably the reason given that about six panels are spread out over the same area in the residential area. Whereas, I have one panel doing the whole floor in the commercial area.



But the residential area is probably multiple suites? See rule 26-602


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## Viggmundir (Sep 13, 2019)

ColbyL said:


> Honestly, given what you're saying, the thing I'm most worried about is the lights. That hallway circuit goes everywhere with about 10+ lights on the circuit. Some things are switched, some things are night lights. The exit signs and the EM pack also are on that circuit. I have almost no doubt I'm over a 3% volt drop. But I suppose it doesn't matter for LED lights. I think there's even a bathroom fan on the damned thing.
> 
> But this is the circuit the owner of the company told me to run in #14. So whatever.


You say LED lights, do you have the specs for those lights? Because a 4' surface wrap fixture may only use 40-50W. 10 fixtures of that would be 400-500W, which is only 3.33A - 4.17A. Exit lights don't use much power.

3% voltage drop on 4A on a #14 is 162ft.
3% voltage drop on 5A on a #14 is 130ft.


Often we will calculate voltage drop based on the total circuit load at the farthest point of the circuit, but in reality your amperage goes down after each light fixture, and so depending on circuit length before the first fixture, and how far apart your fixtures are, you may be able to stretch the circuit further.
3% voltage drop on 1A on a #14 is 652ft of run.


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## splatz (May 23, 2015)

I wouldn't think too long about this, run the #12 and go on with your life. But it's a legitimate question. 

Maybe your boss is just mistaken, that's my guess, he's confusing the Samsung instructions with some other spec on a job. Lots of commercial jobs spec nothing smaller than #12 for power wiring. 

If it actually is in the manual, why would someone at Samsung put that in there? 

Maybe they're confused, lots of people confuse that common commercial spec to use nothing smaller than #12 for power with an actual code requirement or electrical requirement. 

There's certainly no electrical reason the same unit would work differently in commercial and residential settings. Long runs are more common in commercial settings, but they happen in residential. Three phase 208V systems are more common in commercial, but they are also common in multi-tenant residential. 

I am not aware of any code reason that would require #12 for these units in commercial settings but I couldn't be 100% sure. I wouldn't be worried about it because I'd have run the #12 without thinking too hard about it.


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## 460 Delta (May 9, 2018)

splatz said:


> I wouldn't think too long about this, run the #12 and go on with your life. But it's a legitimate question.
> 
> Maybe your boss is just mistaken, that's my guess, he's confusing the Samsung instructions with some other spec on a job. Lots of commercial jobs spec nothing smaller than #12 for power wiring.
> 
> ...


Another thing that you sort of touched on, is on a long run with power from a 208 star, like a commercial site, a little voltage drop and you’re suddenly dragging bottom on supplied voltage. The upsized wire is necessary at that point.


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## ColbyL (Jun 21, 2019)

Yea. I am satisfied with the answers I've gotten here. My boss actually let me keep the #14. He told me he only said something because I had put #14 white on the material list and he didn't want to buy more #14 single conductor. I was only panicking because this sounded like a major rule that no one ever clued me in on.


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