45 Wall Mounted TV's

[Dennis Alwon]

This question was posed to me by a friend who is an ec and a member of our NC association of ec.

I suggested that since these were permanent installs I felt that using 210.23(A)(2) would not be necessary instead he had to consider two things-- One is 2400 watts @ 20 amps times 80% for continuous load would give him a max of 1920 watts per circuit. The other aspect was only 13 outlets per circuit based on 180va per outlet.

I am not sure we are limited to 13 outlets if the loads are known. And
If in some areas 2 TV's were to be used in one duplex would the rule change if a tv was only plugged into one of the duplex outlets. It would appear if an outlet was left unused then 210.23(A)(2) would come into play and limit the load to 50%. My response was he could have 19 TV's per circuit max and needed 3 circuits minimum. What do ye say?

The project involves the installation of 45 cord connected led TVs . These TVs are wall or ceiling mounted. I believe these TVs would be considered fixed utilization equipment. So the branch circuit they are on can not be loaded more than 50%. 10 amps on a 20 amp branch. That's 1200va. Each outlet counts as 180 va, although the tv is rated 100va . So I believe 6 duplexes can go on the
branch circuit 1200/180 = 6.66. But they could plug in 12 TVs

Worse yet, these tv are going in concession stands where food is prepared so they are considered non dwelling kitchens so the receptacles need GFI protection. 12 electronic anythings has a lot of leakage current.

 

[petersonra]

How would one ever hook up a fixed plug/cord connected load that exceeded 10A then?

in any case, I am not convinced these are fixed loads since the load will vary depending on brightness and other factors such as how loud the TV is played at.

 

[Dennis Alwon]

I think you have to figure the load at the max but I believe they would be considered fixed since they are bracketed into place. If they weren't fixed then 80% anyway

 

[infinity]

How would a TV possibly be a continuous load? It will never operate at it's maximum current.

 

[Smart $]

How would a TV possibly be a continuous load? It will never operate at it's maximum current.

While I agree a TV cannot be considered a continuous load, it doesn't matter. 210.21(B)(2) limits total cord-and-plug-connected load to 16A on a 20A circuit. However unlikely, there is no guarantee that all the TV's on a circuit will not draw maximum current for an instance.

 

[Smart $]

So how many duplex recept's will power two TV's?

Calculations say...

45 ? 100VA ea = 4500VA
4500VA ? 1920VA max/ckt = 3 ckt's minimum

If we say13 duplex max per ckt, that'll get him 39 with potential to plug in 78 TV's... but every duplex where two are plugged in have to be calculated at 200VA.

While there is potential to plug other loads into duplexes with only one TV, I don't believe 210.23(A)(2) applies because these are not general-use receptacles ? most likely installed high up on wall, and ceilings are likely out of reach for most ? but Code doesn't say this...

 

[__dan]

Without looking up the code references:

You don't want to run the minimum number of circuits. You would want more circuits for the convenience of having more of your monitors staying on when one circuit trips for any reason (extra circuits for redundancy are a saleable item in a high use critical application). TV monitors have the cheapest, least reliable, power supply of most any electronic device and you should expect a heavy harmonic load component. I would probably target loading to 50%, guesstimating. MWBC's will have a heavy neutral load from the harmonics. Also, chances are it is not the electrician who will be plugging in the monitors, so there's no control over loading if you are targeting loading at 80% with the minimum # of circuits.

45 monitors is a command center or trading floor application. Those would be expected to run continuously for the eight hour day and possibly expected to run 7/24/365 if in an OCC.

The NEC covers the fixed wiring of the building and jurisdiction stops at the outlet. Between the outlet and the monitor cord, you would have something like a Tripp-Lite-AVBAR10-Isobar-Protector, giving you more than enough receptacles (these routinely go on sale for $45.).

 

[Dennis Alwon]

How would a TV possibly be a continuous load? It will never operate at it's maximum current.

I am thinking they are on for 3 hours at a time-- didn't realize the power change is that different in vol. etc but as Smart stated 80% it is anyway.

As per the height of the duplex that was my determination also-- using a duplex with one TV didn't matter-- it could be an authority having jurisdiction call.

 

[masterinbama]

Do they not have a UL label on each TV stating wattage for each TV?

 

[Dennis Alwon]

Do they not have a UL label on each TV stating wattage for each TV?

I can only go by the email so I assume they do

 

[cadpoint]

What is not being accounted for is that NC bars allow for illuminated neon signs
in their dining facilities.

IMPO the installer is not accounting for all the aspects of what will be on the walls.
I realize that we are not required to account for future installs but at 80% one maybe
two neon signs could easily push on embarrassment.

The signs usually come in long after the TV's are hung!

 

[infinity]

While I agree a TV cannot be considered a continuous load, it doesn't matter. 210.21(B)(2) limits total cord-and-plug-connected load to 16A on a 20A circuit. However unlikely, there is no guarantee that all the TV's on a circuit will not draw maximum current for an instance.

Isn't that limit of 16 amps on a receptacle not on the circuit. A 20 amp circuit could be loaded to 20 amps non-continuous which a TV would be.

I am not sure we are limited to 13 outlets if the loads are known. And
If in some areas 2 TV's were to be used in one duplex would the rule change if a tv was only plugged into one of the duplex outlets. It would appear if an outlet was left unused then 210.23(A)(2) would come into play and limit the load to 50%.

As far as 50% for fastened in place if the circuit was used solely for the TV's the 50% limitation of 210.23(A)(2) would not apply since you would only have fastened in place equipment.

210.23(A)(2) Utilization Equipment Fastened in Place. The total
rating of utilization equipment fastened in place, other than
luminaires, shall not exceed 50 percent of the branch-
circuit ampere rating where lighting units, cord-and-plug-
connected utilization equipment not fastened in place, or
both, are also supplied.

 

[Smart $]

Isn't that limit of 16 amps on a receptacle not on the circuit. A 20 amp circuit could be loaded to 20 amps non-continuous which a TV would be.

:slaphead: You are correct.

As far as 50% for fastened in place if the circuit was used solely for the TV's the 50% limitation of 210.23(A)(2) would not apply since you would only have fastened in place equipment.

I agree. You can't control what is plugged into a receptacle after installation, even when designed for a specific load. Say you break the duplex jumper tab and only power one side, one TV. What prevents someone from using a 3 to 1 or power strip to add loads?

 

[mgookin]

Do they need a cable box at each tv? More loads.

 

[Dennis Alwon]

Do they need a cable box at each tv? More loads.

I don't think that is normally the case but that info is not given. I can only go by what I have

 

[kwired]

What is not being accounted for is that NC bars allow for illuminated neon signs
in their dining facilities.

IMPO the installer is not accounting for all the aspects of what will be on the walls.
I realize that we are not required to account for future installs but at 80% one maybe
two neon signs could easily push on embarrassment.

The signs usually come in long after the TV's are hung!

True, but what is worst thing that will happen if it is overloaded? This kind of infringes on NEC becoming a design manual. Now careful load selection makes more sense for the NEC to cover for critical circuits type of applications. But maybe when a big game is on the TV's in the bar, it is a matter of life or death should the breaker supplying all of them trip:happyyes:

The bartender's life is probably on the line at the very least.

 

[mgookin]

Is the sound coming from the tv's or is it being piped through the house system?

 

[cadpoint]

The electrician look silly is really about all.

True, but what is worst thing that will happen if it is overloaded?

The definition of design can be either a noun or a verb.

....purpose,planning, or intention that exists or is thought to exist behind an action, fact, or material object.

....door plan (something) with a specific purpose or intention in mind. Respectfully.

The NFPA is just using lawyer speak to use that statement, of this is not a design manual(period)

The OP should be smart enough to label all circuits correctly, etc.

There is a NFPA article for a interior frontage sign power receptacle. The OP should consider
adding wattage for these circuit(s). The beer signs will happen here in a NC sports bar!

 

[broadgage]

I would say that a TV IS a continous load in this application.
Virtualy certain to be on throughout the working day, much longer than 3 hours. The loading of most modern TVs varies only very slightly by programe content and can IMHO be regarded as continous.

It would therefore seem to me that if the outlets are out of easy reach and unlikely to be used for anything else, then the circuits could be designed for up to but not exceeding, 16 amps on a 20 amp circuit.

It would however IMHO be a better design to limit the number of TV sets per circuit to a much lower value than that. Consider firstly the inrush current after a brief power failure, and secondly the loss of trade or reputation if a fault in one TV trips the breaker and puts many others out.
Better to have few per circuit in that cases.

 

[petersonra]

I would say that a TV IS a continous load in this application.
Virtualy certain to be on throughout the working day, much longer than 3 hours. The loading of most modern TVs varies only very slightly by programe content and can IMHO be regarded as continous.

It would therefore seem to me that if the outlets are out of easy reach and unlikely to be used for anything else, then the circuits could be designed for up to but not exceeding, 16 amps on a 20 amp circuit.

It would however IMHO be a better design to limit the number of TV sets per circuit to a much lower value than that. Consider firstly the inrush current after a brief power failure, and secondly the loss of trade or reputation if a fault in one TV trips the breaker and puts many others out.
Better to have few per circuit in that cases.

by that logic you would end up with a single circuit per TV. which is not really an awful idea.