commercial receptacle limits
- Thread starter roger
- Start date
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- Location
- Massachusetts
Re: commercial receptacle limits
Neither, 180 VA per yoke, single or duplex.
Re: commercial receptacle limits
The question that was ask was how many 20 amp. receptacles are allowed on a 20 amp. circuit in an office Bldg.
A duplex receptacle has two outlets on it but is considered one receptacle so the answer is 13.
This was not a reading comprehension test or a trick question.
It was an Electrical question on a electrical test was it not?
The current answer at that time would have been 12 if the nominal voltage was 115 volts at that time.115 volts could have been just the number that Roger used when asking the question.We don't no since we didn't see the original question.
This math problem we have been using 115 x 20 divided by 180 va. =12.777 is not in the books anywhere that I have found it is just the way you would figure it from have a little knowledge in math.
If the question where ask today you would use 120 volts and come up with the same answer that appears in the 2002 NEC code book which states 13 receptacles.
If you don't have a code book to see this is the correct answer, how can you possibly argue the point?
If you see it in black and white print in the code book and it says 13 how can you say it is 12?
Ronald
The question that was ask was how many 20 amp. receptacles are allowed on a 20 amp. circuit in an office Bldg.
A duplex receptacle has two outlets on it but is considered one receptacle so the answer is 13.
This was not a reading comprehension test or a trick question.
It was an Electrical question on a electrical test was it not?
The current answer at that time would have been 12 if the nominal voltage was 115 volts at that time.115 volts could have been just the number that Roger used when asking the question.We don't no since we didn't see the original question.
This math problem we have been using 115 x 20 divided by 180 va. =12.777 is not in the books anywhere that I have found it is just the way you would figure it from have a little knowledge in math.
If the question where ask today you would use 120 volts and come up with the same answer that appears in the 2002 NEC code book which states 13 receptacles.
If you don't have a code book to see this is the correct answer, how can you possibly argue the point?
If you see it in black and white print in the code book and it says 13 how can you say it is 12?
Ronald
joe tedesco
Senior Member
- Location
- Boston, Massachusetts
Re: commercial receptacle limits
To all Code Scholars and friends:
And now here's the rest of the story!
20 A x 115V (the specified voltage)= 2300 VA
2300VA/180VA = 12.777 rounded down to 12 device yokes, or straps containing receptacles.
Section 220.3(B)(9) provides the 180 VA single, or multiple receptacle on one yoke.
This section also indicates that for a single piece of equipment, containing 4 or more receptacles, the computation is 90VA per receptacle.
Therefore, any yoke or strap that has 3 or less receptacles, is considered to be 180 VA.
Based upon the definition of "receptacle" in Article 100, the true answer to this question is:
12 yokes x maximum 3 receptacles per yoke = 36 receptacles.
The original question asked: "How many receptacles can be installed..."
Terminology is very important in writing defensible test questions, and with the answers
that were provided the question should have read,
"How many duplex receptacles can be installed on a 20 ampere, 115 volt branch circuit in a
commercial office building?"
Think real hard before putting your foot {now feet} into your mouth before you ask for the next dance!!
Joe Tedesco www.joetedesco.com
[ August 07, 2003, 10:36 AM: Message edited by: joe tedesco ]
To all Code Scholars and friends:
And now here's the rest of the story!
20 A x 115V (the specified voltage)= 2300 VA
2300VA/180VA = 12.777 rounded down to 12 device yokes, or straps containing receptacles.
Section 220.3(B)(9) provides the 180 VA single, or multiple receptacle on one yoke.
This section also indicates that for a single piece of equipment, containing 4 or more receptacles, the computation is 90VA per receptacle.
Therefore, any yoke or strap that has 3 or less receptacles, is considered to be 180 VA.
Based upon the definition of "receptacle" in Article 100, the true answer to this question is:
12 yokes x maximum 3 receptacles per yoke = 36 receptacles.
The original question asked: "How many receptacles can be installed..."
Terminology is very important in writing defensible test questions, and with the answers
that were provided the question should have read,
"How many duplex receptacles can be installed on a 20 ampere, 115 volt branch circuit in a
commercial office building?"
Think real hard before putting your foot {now feet} into your mouth before you ask for the next dance!!
Joe Tedesco www.joetedesco.com
[ August 07, 2003, 10:36 AM: Message edited by: joe tedesco ]
- Location
- Illinois
- Occupation
- retired electrician
Re: commercial receptacle limits
Joe,
Where does it say you have to make the calculation the way you did it? The only thing that determines how many duplex receptacles can be installed is the load. If you do the calculation a different way the "code" load for the circuit is 20 amps.
180va/115 volts = 1.565 amps per duplex
13 duplex receptacles at 1.565 amps = 20.345 amps
The code permits fractional amps of less than 0.5 amps to be dropped. When I drop the fractional amp, I have a load of 20 amps for 13 duplex receptacles on a 115 volt 20 amp branch circuit. What code sections says I can't use this method of making the load calculation?
Don
Joe,
Where does it say you have to make the calculation the way you did it? The only thing that determines how many duplex receptacles can be installed is the load. If you do the calculation a different way the "code" load for the circuit is 20 amps.
180va/115 volts = 1.565 amps per duplex
13 duplex receptacles at 1.565 amps = 20.345 amps
The code permits fractional amps of less than 0.5 amps to be dropped. When I drop the fractional amp, I have a load of 20 amps for 13 duplex receptacles on a 115 volt 20 amp branch circuit. What code sections says I can't use this method of making the load calculation?
Don
joe tedesco
Senior Member
- Location
- Boston, Massachusetts
Re: commercial receptacle limits
The original question did not use the term "Duplex" read my reply again Don!
The original question did not use the term "Duplex" read my reply again Don!
- Location
- Illinois
- Occupation
- retired electrician
Re: commercial receptacle limits
Joe,
Ok, then I'll ask it this way. Does the 2002 NEC permit the installation of 13 duplex receptacles on a 115 volt, 20 amp branch circuit in a commerical occupancy? If you say the answer is no, please cite a code section that says I can't do the load calculation as shown in my post of August 07, 2003 09:50 AM.
Don
Joe,
Ok, then I'll ask it this way. Does the 2002 NEC permit the installation of 13 duplex receptacles on a 115 volt, 20 amp branch circuit in a commerical occupancy? If you say the answer is no, please cite a code section that says I can't do the load calculation as shown in my post of August 07, 2003 09:50 AM.
Don
Re: commercial receptacle limits
12 if Joe is the instructor.
13 if Don is the instructor.
Unfortunately we did have to make assumptions for this question.
We had to assume duplex receptacles (or something to get us to 180VA per "recept") or the choices did not make sense (as Joe pointed out 36 would be the answer (or would it be 39???))
We had to make an assumption if 115V was the nominal voltage or not. The question could have just as easily been a trick question the other way – making sure we used the nominal voltage of 120V in the calculation, not the slang 115V.
If I’m in the U.S. and somebody asks a question with 110V or 115V in it... I’m thinkin’ 120V nominal.
I guess the question did contain enough information to answer.
12 if Joe is the instructor.
13 if Don is the instructor.
Unfortunately we did have to make assumptions for this question.
We had to assume duplex receptacles (or something to get us to 180VA per "recept") or the choices did not make sense (as Joe pointed out 36 would be the answer (or would it be 39???))
We had to make an assumption if 115V was the nominal voltage or not. The question could have just as easily been a trick question the other way – making sure we used the nominal voltage of 120V in the calculation, not the slang 115V.
If I’m in the U.S. and somebody asks a question with 110V or 115V in it... I’m thinkin’ 120V nominal.
I guess the question did contain enough information to answer.
joe tedesco
Senior Member
- Location
- Boston, Massachusetts
Re: commercial receptacle limits
Using that rationale, when we figure what the VA is per outlet (strap), the result is less than 180 VA.
Section 220.3(B)(9) indicates that the minimum per strap is 180VA.
20 x 115 = 2300 VA 2300VA/13 = 176.9 or 177 VA per outlet, less than the required 180VA
Using that rationale, when we figure what the VA is per outlet (strap), the result is less than 180 VA.
Section 220.3(B)(9) indicates that the minimum per strap is 180VA.
20 x 115 = 2300 VA 2300VA/13 = 176.9 or 177 VA per outlet, less than the required 180VA
Re: commercial receptacle limits
Based upon the responses given by the knowledgable people here, it seems that this question would have little value as a multiple choice test question. On the other hand, if this were a test that required the answers to be substantiated by code references, you'd have a chance to see how well the test takers can read and understand some of the finer details of the code.
Based upon the responses given by the knowledgable people here, it seems that this question would have little value as a multiple choice test question. On the other hand, if this were a test that required the answers to be substantiated by code references, you'd have a chance to see how well the test takers can read and understand some of the finer details of the code.
- Location
- Massachusetts
Re: commercial receptacle limits
As a multiple choice question it is bogus, as an SA question you could really tell if the folks understand how to arrive at the answer.
Welcome Robrr and may I say I agree with you.
As a multiple choice question it is bogus, as an SA question you could really tell if the folks understand how to arrive at the answer.
- Location
- Illinois
- Occupation
- retired electrician
Re: commercial receptacle limits
Joe,
I did my calculation at 180 va per strap. I just chose to do the calculation in a manner where the code clearly permits rounding. Even if I do it like this, I still get a 20 amp "code" load.
13 x 180va = 2340 va 2340va/115v = 20.348 amps. The code permits me to drop the .348 amps giving me a "code" load of 20 amps which is permitted on a 20 amp circuit.
As I told Roger, we'll have to agree to disagree on this one. I will insist that 13 are permitted until someone can show me a code rule that says 2340 va is not permitted by the code on a 115 volt, 20 amp circuit.
Don
Joe,
I did my calculation at 180 va per strap. I just chose to do the calculation in a manner where the code clearly permits rounding. Even if I do it like this, I still get a 20 amp "code" load.
13 x 180va = 2340 va 2340va/115v = 20.348 amps. The code permits me to drop the .348 amps giving me a "code" load of 20 amps which is permitted on a 20 amp circuit.
As I told Roger, we'll have to agree to disagree on this one. I will insist that 13 are permitted until someone can show me a code rule that says 2340 va is not permitted by the code on a 115 volt, 20 amp circuit.
Don
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: commercial receptacle limits
Don,
As a moderator of this forum you are able to conduct a poll, correct? This topic would be a fun one to try it with. How many say 12 and how many say 13
[ August 07, 2003, 03:57 PM: Message edited by: ryan_618 ]
Don,
As a moderator of this forum you are able to conduct a poll, correct? This topic would be a fun one to try it with. How many say 12 and how many say 13
[ August 07, 2003, 03:57 PM: Message edited by: ryan_618 ]
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: commercial receptacle limits
[ August 07, 2003, 03:56 PM: Message edited by: ryan_618 ]
[ August 07, 2003, 03:56 PM: Message edited by: ryan_618 ]
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: commercial receptacle limits
Don: I suggest that we not do that. The notion of ?how many say 12, and how many say 13? has no meaning whatsoever. You can vote to pass a bill or to put a person into office, but you cannot vote truth. Nor can you vote reality. If a person takes comfort by being a member of the group that expresses the majority opinion, or if a person is prepared to say, ?See, more people agree with my answer, and so therefore my answer is right,? then I say that person is not thinking clearly.
Before you give a meaningful answer, you must first understand the question. The question originally posed in this thread included the number 115. Anyone who uses the number 120 in their calculation will have the wrong answer. That is truth, and no opinion poll can alter that truth. BUT: Does the original question have any real bearing on the design and construction of commercial office buildings under the 2002 NEC? THAT?S A DIFFERENT MATTER ENTIRELY!!!!!
So, ryan_618, if you insist on our running a poll, then let me request that you present, for our consideration, the question for which you seek to know ?how many say 12, and how many say 13.?
Don: I suggest that we not do that. The notion of ?how many say 12, and how many say 13? has no meaning whatsoever. You can vote to pass a bill or to put a person into office, but you cannot vote truth. Nor can you vote reality. If a person takes comfort by being a member of the group that expresses the majority opinion, or if a person is prepared to say, ?See, more people agree with my answer, and so therefore my answer is right,? then I say that person is not thinking clearly.
Before you give a meaningful answer, you must first understand the question. The question originally posed in this thread included the number 115. Anyone who uses the number 120 in their calculation will have the wrong answer. That is truth, and no opinion poll can alter that truth. BUT: Does the original question have any real bearing on the design and construction of commercial office buildings under the 2002 NEC? THAT?S A DIFFERENT MATTER ENTIRELY!!!!!
So, ryan_618, if you insist on our running a poll, then let me request that you present, for our consideration, the question for which you seek to know ?how many say 12, and how many say 13.?
Re: commercial receptacle limits
Charlie I do not understand about the number 115 the new code is using 120 and allows 13 on a 20 ampere circuit.
Everyone has more or less agreed that the nominal voltage of 115 was used when the question was written and it would have been 12 then ,but would be 13 now.
The way the question is worded the correct answer would be 12 we no that but the correct answer now is 13.
It is in the code book in black and white print you can put 13 duplex recepacles on a 20 amp. circuit.
Ronald
Charlie I do not understand about the number 115 the new code is using 120 and allows 13 on a 20 ampere circuit.
Everyone has more or less agreed that the nominal voltage of 115 was used when the question was written and it would have been 12 then ,but would be 13 now.
The way the question is worded the correct answer would be 12 we no that but the correct answer now is 13.
It is in the code book in black and white print you can put 13 duplex recepacles on a 20 amp. circuit.
Ronald
Re: commercial receptacle limits
Posted by Charlie Does the original question have any real bearing on the design and construction of commercial office buildings under the 2002 NEC? THAT?S A DIFFERENT MATTER ENTIRELY!!!!!
Charlie would you please translate this sentence above into what you meant.For some here that don't know the truth?
If the question applied now it would be 13 according to the 2002 NEC.
Ronald
Posted by Charlie Does the original question have any real bearing on the design and construction of commercial office buildings under the 2002 NEC? THAT?S A DIFFERENT MATTER ENTIRELY!!!!!
Charlie would you please translate this sentence above into what you meant.For some here that don't know the truth?
If the question applied now it would be 13 according to the 2002 NEC.
Ronald
- Location
- Lockport, IL
- Occupation
- Semi-Retired Electrical Engineer
Re: commercial receptacle limits
[ August 08, 2003, 06:07 PM: Message edited by: charlie b ]
I hope to clear up a misunderstanding by splitting a hair here. It is not a matter of one answer being right then, and a different answer being right now. It is a matter of a different question being asked then, and a new question being asked now. If you write the question with the number 115 in it, the answer was 12 and will be 12, now and forever. It?s just that that question is no longer of any interest. The question you should ask today, based on today?s code, would have 120 in the question. The answer to the 120 question would have been 13 a thousand years ago (even if no-one would have understood that question back then), and will always be 13. The answer has not changed, but the question has changed.
[ August 08, 2003, 06:07 PM: Message edited by: charlie b ]
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