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chez bouton 12-15-2013 01:43 PM

NEC - what is the purpose of some of these codes ?
 
Hello,

I assume that the reason for each NEC regulation is related to improved safety, but some of them I do not understand what is improved.

Can anyone explain what is the purpose of restricting a circuit in a laundry room to only serve that laundry room ? What is the added risk of, for instance, allowing laundry room outlet circuit to also supply additional room(s) ?

Similarly, what is the purpose of restricting bathroom dedicated (required) circuit to only serve that (or another) bathroom ? Seems odd that I can supply one circuit for 2 bathrooms but not use the circuit for one bathroom and one adjoining room ?

And lastly, what is reason that we can use one circuit for the outlets in 2 bathrooms, unless we also add lighting to the circuit, in which case, we are now restricted to using that circuit in only the bathroom of outlets+lighting ?

Can anyone explain how safety is improved by these regulations ?
I am just trying to understand.

Thanks,
Patrick

stickboy1375 12-15-2013 02:00 PM

The NEC crosses some lines as it is not supposed to be a design manual, but in these scenarios, The NEC disregards it's own rules, I don't see any safety reasons for these rules, but they are high demand areas for electrical use.

gregzoll 12-15-2013 02:07 PM

You have less people having house fires, getting electrocuted when standing on wet pavement, ground, etc. Yes a lot of it is Lawyer speak, but it is there to not only protect those who have to perform the work, from the liability placed on them, it also protects those inside the structure and the structure and/or equipment attached to the circuit.

ratherbefishing 12-15-2013 02:23 PM

I figured it was so a hair dryer (one of the largest 110V loads in the house) doesn't make other rooms dark, when it blows the fuse.

ddawg16 12-15-2013 02:44 PM

My comments (opinions) in red.....

The important thing to remember is that the NEC is attempting to protect homes from ALL possible problems. While a majority of the time most of us have common sense...there are too many people who do not.

Quote:

Originally Posted by chez bouton (Post 1278715)
Hello,

I assume that the reason for each NEC regulation is related to improved safety, but some of them I do not understand what is improved.

Can anyone explain what is the purpose of restricting a circuit in a laundry room to only serve that laundry room ? What is the added risk of, for instance, allowing laundry room outlet circuit to also supply additional room(s) ? A common tool in there is the iron....figure 10amps or so...then add to that maybe a space heater in the next room on the same ckt?

Similarly, what is the purpose of restricting bathroom dedicated (required) circuit to only serve that (or another) bathroom ? Seems odd that I can supply one circuit for 2 bathrooms but not use the circuit for one bathroom and one adjoining room ? Typical hair dryer is going to pull up to 10amps. If you had another outlet....what stops someone from plugging in a vacuum?

And lastly, what is reason that we can use one circuit for the outlets in 2 bathrooms, unless we also add lighting to the circuit, in which case, we are now restricted to using that circuit in only the bathroom of outlets+lighting ? I thought the bathroom ckt could only supply 1 bathroom....not two? As for lights....they are not going to pull nearly as much as a vacuum or hair dryer.

Can anyone explain how safety is improved by these regulations ?
I am just trying to understand.

Thanks,
Patrick


chez bouton 12-15-2013 05:39 PM

ddawg ... thanks for the info.

regarding one circuit supplying 2 bathrooms, here is my understanding :
NEC 210.11(C)(3) requires, in dwelling units, that at least one 20-ampere branch circuit must be provided to supply bathroom receptacle outlets. Such circuits shall have no other outlets. However, there is an exception to 210.11(C)(3)that says where the 20-ampere circuit supplies only one bathroom, outlets for other equipment within the same bathroom are permitted to be supplied in accordance with 210.23(A)(1) and (A)(2). However the Exception to 210.23(A) tells us the bathroom branch circuits required by 210.11(C)(3) shall supply only the receptacle outlets specified in that section. - See more at: http://neca-neis.org/cqd/index.cfm?f....4KLzjKgE.dpuf

NEC 210.11(C)(3) requires, in dwelling units, that at least one 20-ampere branch circuit
must be provided to supply bathroom receptacle outlets.
Such circuits shall have no other outlets.
However, there is an exception to 210.11(C)(3)that says where
the 20-ampere circuit supplies only one bathroom,
outlets for other equipment within the same bathroom
are permitted to be supplied in accordance with
210.23(A)(1) and (A)(2).
However the Exception to 210.23(A) tells us the
bathroom branch circuits required by 210.11(C)(3)
shall supply only the receptacle outlets specified in that
section.

Thus, the idea that a hairdryer + vacuum is a problem but 2 hairdryers simultaneously (one in each of 2 bathrooms on the same circuit) is not a problem is not convincing.

Still not obvious to me what is gained (in terms of safety) by these specific code sections.

Thanks much.
NEC 210.11(C)(3) requires, in dwelling units, that at least one 20-ampere branch circuit must be provided to supply bathroom receptacle outlets. Such circuits shall have no other outlets. However, there is an exception to 210.11(C)(3)that says where the 20-ampere circuit supplies only one bathroom, outlets for other equipment within the same bathroom are permitted to be supplied in accordance with 210.23(A)(1) and (A)(2). However the Exception to 210.23(A) tells us the bathroom branch circuits required by 210.11(C)(3) shall supply only the receptacle outlets specified in that section. - See more at: http://neca-neis.org/cqd/index.cfm?f....4KLzjKgE.dpuf
The main rule in 210.11(C)(3) states that the branch circuit provided to supply the bathroom receptacle outlet(s) shall have no other outlets. No lighting outlets or other equipment can be fed from the same circuit feeding the bathroom receptacles. For example, a one-family dwelling has two bathrooms and a duplex receptacle has been installed in each. One 20-ampere branch circuit can supply power to both bathroom receptacles but cannot feed anything else.
Neither garage receptacles nor outside receptacles are permitted on the 20-ampere bathroom branch circuit. Since this branch circuit supplies two bathrooms, only bathroom receptacles are permitted on the circuit. This circuit cannot supply lights, exhaust fans or other equipment. (See Figure 7)
Where the 20-ampere branch circuit supplies only one bathroom, outlets for other equipment within the same bathroom can be on the same circuit. As long as the circuit feeds only one bathroom, it can supply power to receptacles, luminaires (lighting fixtures), exhaust fans, etc. The circuit must be installed in accordance with the provisions in 210.23(A). [210.11(C)(3)]
For example, two bathrooms are located at opposite ends of the house. One bathroom contains two duplex receptacles, a luminaire (light fixture) and an exhaust fan. As long as the branch circuit feeding the receptacles does not leave that particular bathroom, it can also supply power to the light fixture and exhaust fan. No other equipment is permitted on the same circuit if the circuit supplies receptacles in more than one bathroom. (See Figure 8)
- See more at: http://www.ecmag.com/section/your-bu....BIBSE0hf.dpuf
The main rule in 210.11(C)(3) states that the branch circuit provided to supply the bathroom receptacle outlet(s) shall have no other outlets. No lighting outlets or other equipment can be fed from the same circuit feeding the bathroom receptacles. For example, a one-family dwelling has two bathrooms and a duplex receptacle has been installed in each. One 20-ampere branch circuit can supply power to both bathroom receptacles but cannot feed anything else.
Neither garage receptacles nor outside receptacles are permitted on the 20-ampere bathroom branch circuit. Since this branch circuit supplies two bathrooms, only bathroom receptacles are permitted on the circuit. This circuit cannot supply lights, exhaust fans or other equipment. (See Figure 7)
Where the 20-ampere branch circuit supplies only one bathroom, outlets for other equipment within the same bathroom can be on the same circuit. As long as the circuit feeds only one bathroom, it can supply power to receptacles, luminaires (lighting fixtures), exhaust fans, etc. The circuit must be installed in accordance with the provisions in 210.23(A). [210.11(C)(3)]
For example, two bathrooms are located at opposite ends of the house. One bathroom contains two duplex receptacles, a luminaire (light fixture) and an exhaust fan. As long as the branch circuit feeding the receptacles does not leave that particular bathroom, it can also supply power to the light fixture and exhaust fan. No other equipment is permitted on the same circuit if the circuit supplies receptacles in more than one bathroom. (See Figure 8)
- See more at: http://www.ecmag.com/section/your-bu....BIBSE0hf.dpuf
The main rule in 210.11(C)(3) states that the branch circuit provided to supply the bathroom receptacle outlet(s) shall have no other outlets. No lighting outlets or other equipment can be fed from the same circuit feeding the bathroom receptacles. For example, a one-family dwelling has two bathrooms and a duplex receptacle has been installed in each. One 20-ampere branch circuit can supply power to both bathroom receptacles but cannot feed anything else.
Neither garage receptacles nor outside receptacles are permitted on the 20-ampere bathroom branch circuit. Since this branch circuit supplies two bathrooms, only bathroom receptacles are permitted on the circuit. This circuit cannot supply lights, exhaust fans or other equipment. (See Figure 7)
Where the 20-ampere branch circuit supplies only one bathroom, outlets for other equipment within the same bathroom can be on the same circuit. As long as the circuit feeds only one bathroom, it can supply power to receptacles, luminaires (lighting fixtures), exhaust fans, etc. The circuit must be installed in accordance with the provisions in 210.23(A). [210.11(C)(3)]
For example, two bathrooms are located at opposite ends of the house. One bathroom contains two duplex receptacles, a luminaire (light fixture) and an exhaust fan. As long as the branch circuit feeding the receptacles does not leave that particular bathroom, it can also supply power to the light fixture and exhaust fan. No other equipment is permitted on the same circuit if the circuit supplies receptacles in more than one bathroom. (See Figure 8)
- See more at: http://www.ecmag.com/section/your-bu....BIBSE0hf.dpuf

chez bouton 12-15-2013 05:41 PM

Sorry for all of the text in the preceding message ... was having some difficulty with the editor !

westom 12-15-2013 07:10 PM

Quote:

Originally Posted by chez bouton (Post 1278715)
Can anyone explain how safety is improved by these regulations ?

Unknown concepts are behind these rules. For example, a circuit breaker is only secondary protection. A circuit should be wired so that occupant could not overload it. A circuit breaker maybe (not always) trips when a circuit is accidentally overloaded.

A 20 amp breaker need not trip on more than 20 amps. For example, a 20 amp breaker can conduct 25 amps for as much as two hours before tripping. Just one reason why the breaker alone is insufficient for safety. And why other rules (ie limiting number of appliances to a laundry room circuit) are also needed.

Some rules are subject to an inspector's interpretation. For example, we wired an overhead bathroom light to a separate circuit. No receptacles or exposed metal was on that circuit. Light was well beyond what anyone could touch. We did this so that a tripped GFCI circuit did not leave an occupant lost in the dark. Especially since this was a handicapped house. The inspector wanted all bathroom lights on the same GFCI. A tripped GFCI left a handicapped person stuck in a completely darkened room.

Since no protection is complete, then protection is layered. Locate outlets on circuit so that a typical homeowner would not put, for example, too many hairdryers simultaneously on one circuit. Two 13 amps hairdryers may not trip a breaker while drawing 26 amps on a 20 amp circuit.

Primary protection is to not overload a circuit by selecting circuits for each receptacle. Circuit breaker is only secondary protection.

dmxtothemax 12-16-2013 05:44 AM

The purpose of codes is to keep thousands of beaurocrates employed !

Easy !

Philly Master 12-16-2013 06:22 AM

but if you have 4 bathrooms you could have all 4 of the bathroom outlets on 1 circuit ...LOL

Jim Port 12-16-2013 06:36 AM

Quote:

Originally Posted by Philly Master (Post 1278944)
but if you have 4 bathrooms you could have all 4 of the bathroom receptacles on 1 circuit ...LOL

Fixed it for you. Outlets would include the lighting and would not be allowed since you are serving more than one bathroom.

stickboy1375 12-16-2013 07:14 AM

The best way to find out how this code was injected into the NEC is to research the NEC ROP (Report on Proposals) to see if someone submitted this change….

Otherwise, you are just going to get hundreds of useless opinions on why it exists today…..

Philly Master 12-16-2013 07:16 AM

Quote:

Originally Posted by Jim Port (Post 1278947)
Fixed it for you. Outlets would include the lighting and would not be allowed since you are serving more than one bathroom.


:laughing: I was wearing my DIY hat ....:whistling2:

herdfan 12-16-2013 09:19 AM

I actually understand most of the reasons for the codes. Some are for real reasons and some are to protect the dumbest among us.

What I don't understand is why some pro's throw a fit and call some of us homeowners and DIY'ers dumb when we want to exceed the code. Do something that is electrically safe, but technically against code and you a complete dumba**.

But want to wire a house with all 12AWG and you are also a complete dumba**.

:confused1:

itsnotrequired 12-16-2013 12:16 PM

Quote:

Originally Posted by herdfan (Post 1278978)
I actually understand most of the reasons for the codes. Some are for real reasons and some are to protect the dumbest among us.

What I don't understand is why some pro's throw a fit and call some of us homeowners and DIY'ers dumb when we want to exceed the code. Do something that is electrically safe, but technically against code and you a complete dumba**.

But want to wire a house with all 12AWG and you are also a complete dumba**.

:confused1:

it is an issue of dollars and time. a pro bidding out a job is going to bid code minimum (unless the customer makes some specific requests). to bid 'beyond code' would price them out of the job.

there is also practical reasons where going beyond code can cause problems. for example, running #10 awg for a receptacle circuit. nothing in the code prevents that but good luck finding a receptacle that can take #10 awg conductors. issues can also come up with conductor fill in boxes. extra and/or increased size conductors can create a problem that isn't anticipated when the decision is made to go beyond code.

all that being said, i have no problem with diyers going beyond code, as long as the installation still meets code. after all, it is their money and time. :)


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