What is "near" in the NEC?

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JDavidS

Member
Location
Bethesda, MD
Occupation
Sytem Integrator (low voltage)
I'm in a discussion with someone about antenna discharge units for amateur radio stations. Per the NEC:
810.20- Antenna Discharge Units - Receiving Stations.
(B.) Location: Antenna discharge units shall be located outside the building or inside the building between the point of entrance of the lead0in and the radio set or transformers and as near as practicable to the entrance of the conductors to the building. Antenna discharge units shall not be located near combustible material or in a hazardous (classified) location as defined in Article 500.

The question has to do with the last sentence regarding combustible materials. What does the NEC define as "near"? I can't find a definition anywhere. The other person says it is bo more than a Toaster, Oven, Heater, Coffee Pot, Christmas lights etc. I say due to the large voltages and current involved it has to be much farther. However, I can't find anything in the NEC which defines what they consider as "near" in this situation.

Can someone help point me in the right direction?

TIA.
 

tom baker

First Chief Moderator
Staff member
There is a similar wording for the service entrance disconnect to be located near the point of entrance. Often this puts the service disconnect back to back the meter. In this case and yours it’s to prevent fires. In the 50 plus antenna discharge units I installed, I ran the unlisted coax inside the building, to the supressor, and ran listed coax to the equipment.
it’s simply a fire issue, as most outside coax is not listed and in a lightning event could melt…
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
There is a similar wording for the service entrance disconnect to be located near the point of entrance. Often this puts the service disconnect back to back the meter. In this case and yours it’s to prevent fires. In the 50 plus antenna discharge units I installed, I ran the unlisted coax inside the building, to the supressor, and ran listed coax to the equipment.
it’s simply a fire issue, as most outside coax is not listed and in a lightning event could melt…
Why would unlisted coax melt and listed coax not melt?
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Why would unlisted coax melt and listed coax not melt?

Actually unlisted coax (as well as most outside plant telcom cables) will support combustion quite easily. The jackets are formulated only to provide maximum weather/UV resistance and flooding compounds can be flammable also if used. Anything with a listing suitable for use inside buildings and walls will have resistance to flame spread and smoke generation. This is why the length of outside plant cables entering buildings is restricted to five feet, after which it must transition to a listed cable. That transition is usually at a ground block or telecom terminal or protector.

-Hal
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Like may of the subjective rules in the NEC, only YOUR AHJ knows what the word "near" means for the purposes of this code rule.
 

JDavidS

Member
Location
Bethesda, MD
Occupation
Sytem Integrator (low voltage)
Like may of the subjective rules in the NEC, only YOUR AHJ knows what the word "near" means for the purposes of this code rule.
Thanks, Don. that's what I was afraid of. The problem here is different inspectors sometimes have different opinions on things like this.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Thanks, Don. that's what I was afraid of. The problem here is different inspectors sometimes have different opinions on things like this.
There is just no way to write the code in a manner that would remove all of the subjective rules, but you are correct that different AHJs will see subjective rules differently.
For this application, I would be looking to the UL Guide Information and/or the manufacturer's instructions as to the permitted location of the antenna discharge equipment in relation to combustible materials.
 

JDavidS

Member
Location
Bethesda, MD
Occupation
Sytem Integrator (low voltage)
There is just no way to write the code in a manner that would remove all of the subjective rules, but you are correct that different AHJs will see subjective rules differently.
For this application, I would be looking to the UL Guide Information and/or the manufacturer's instructions as to the permitted location of the antenna discharge equipment in relation to combustible materials.
Unfortunately, therein lies the problem. The manufacturer's typically don't have instructions as to the location in relation to combustible materials. I've seen some pretty bad installs over the years - like mounted on a piece of plywood sitting on a wooden desk. People just don't realize the danger.
 

romex jockey

Senior Member
Location
Vermont
Occupation
electrician
I'm a collector of older NEC's . I've some that hail from the mid 50's , they were written in plain english for HS dropouts, and sized for the back pockets of work pants.....

FF to the new millennium, it's far lager, has more exceptions than rules, has numerous 'correlating commitees' trying to make sense of it all, along with those that actually have had a hand writing it that can't seem to agree on it's specifics

Further, it's modus operandi goal of safety is no more than that of profit cloaked in the guise of it

subjective/ objective ?

live it......

~RJ~
 

JDavidS

Member
Location
Bethesda, MD
Occupation
Sytem Integrator (low voltage)
I'm a collector of older NEC's . I've some that hail from the mid 50's , they were written in plain english for HS dropouts, and sized for the back pockets of work pants.....

FF to the new millennium, it's far lager, has more exceptions than rules, has numerous 'correlating commitees' trying to make sense of it all, along with those that actually have had a hand writing it that can't seem to agree on it's specifics

Further, it's modus operandi goal of safety is no more than that of profit cloaked in the guise of it

subjective/ objective ?

live it......

~RJ~
Thanks for the information on older copies. I've only been doing this since the early 2000's, so am not familiar with those. But it's very interesting.
I do disagree on one point though. I do think the intent of the NEC is safety. The execution isn't always smooth, but that's how it goes when you have rule by committee. The ICC is the same way - in their case too many special interests have been able to worm their way into the codes, the result being more money in their pockets.
The problem is I just don't know of a better way. One person or even a few people can't do it. The NEC needs the wide range of experience that many electricians and other professionals can lend to the process.
 

romex jockey

Senior Member
Location
Vermont
Occupation
electrician
Thanks for the information on older copies. I've only been doing this since the early 2000's, so am not familiar with those. But it's very interesting.
I do disagree on one point though. I do think the intent of the NEC is safety. The execution isn't always smooth, but that's how it goes when you have rule by committee. The ICC is the same way - in their case too many special interests have been able to worm their way into the codes, the result being more money in their pockets.
The problem is I just don't know of a better way. One person or even a few people can't do it. The NEC needs the wide range of experience that many electricians and other professionals can lend to the process.
Those 'special interests' didn't happen overnight JD, nor where they exclusive to the NEC. The fact is , no regulatory oversight remains unbiased when it can hide behind bureaucracies so extraneous any given code aficionado can have his/her own interpretation of it.....
:cool:
~RJ~
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Like may of the subjective rules in the NEC, only YOUR AHJ knows what the word "near" means for the purposes of this code rule.
It is a huge problem if we are all subject to relying on one EI's interpretation of what he believes "near" SHOULD BE. There should be a Code standard (in specific cases like this one) for each state that all EC's are required to follow with no exceptions. In NJ we have a Code Assistance unit that can give you specific information regarding a Code issue and if necessary will contact the EI for clarification or additional information in order to resolve the issue. Hope the OP has one of those in MD.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Those 'special interests' didn't happen overnight JD, nor where they exclusive to the NEC. The fact is , no regulatory oversight remains unbiased when it can hide behind bureaucracies so extraneous any given code aficionado can have his/her own interpretation of it.....
:cool:
~RJ~
You said it better than I did :cool:
 

JDavidS

Member
Location
Bethesda, MD
Occupation
Sytem Integrator (low voltage)
Those 'special interests' didn't happen overnight JD, nor where they exclusive to the NEC. The fact is , no regulatory oversight remains unbiased when it can hide behind bureaucracies so extraneous any given code aficionado can have his/her own interpretation of it.....
:cool:
~RJ~
No, they didn't. But how would you change the system? You need input from many sources to get a complete picture of what's going on. But that's where the special interests come in. So what's the solution? One or even a dozen persons cannot do it.
 

JDavidS

Member
Location
Bethesda, MD
Occupation
Sytem Integrator (low voltage)
It is a huge problem if we are all subject to relying on one EI's interpretation of what he believes "near" SHOULD BE. There should be a Code standard (in specific cases like this one) for each state that all EC's are required to follow with no exceptions. In NJ we have a Code Assistance unit that can give you specific information regarding a Code issue and if necessary will contact the EI for clarification or additional information in order to resolve the issue. Hope the OP has one of those in MD.
That's a nice idea but the person I'm talking with isn't here in MD. I'm not sure where he is, but since he's not an electrical contractor he wouldn't have access to a Code Assistance unit, even if his state had one.

I think it would be better if the code were more specific, especially in a case like this where lightning is involved.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
It is a huge problem if we are all subject to relying on one EI's interpretation of what he believes "near" SHOULD BE. There should be a Code standard (in specific cases like this one) for each state that all EC's are required to follow with no exceptions. In NJ we have a Code Assistance unit that can give you specific information regarding a Code issue and if necessary will contact the EI for clarification or additional information in order to resolve the issue. Hope the OP has one of those in MD.
Start writing your PIs for the 2026 code...clarifying all of the subjective rules in the NEC to rules that are not subjective should only add a 1000 or so pages to the code.
 

jim dungar

Moderator
Staff member
Location
Wisconsin
Occupation
Retired Electrical Engineer - Power Systems
I wish they would stop using subjective words like near. A mile is pretty near compared to ten miles.

Why not just say with five feet.
You are right that the context of the term means everything, but we often try to parse stuff down to a single word. Our English language does not have enough individual words to cover all possible uses.

For service entrance conductors the 'near' concern may be length subject to physical damage, while for heat producing items 'near' may be addressing ventilation.
 

Carultch

Senior Member
Location
Massachusetts
I wish they would stop using subjective words like near. A mile is pretty near compared to ten miles.

Why not just say with five feet.
One explanation is that quantifying the distance depends on the size, scale, mfr, and model, since not all units would require the same clearance.

For instance, a realistic amount of clear space needed around a multi-MVA transformer for effective cooling, is a lot different than the clearance of a 1kVA transformer that you can lift with just one hand. This is a clear space that is better suited for the manufacturer to advise upon, than for the NEC to have a one-size-fits-all dimension, since all transformers have different thermal footprints and cooling methods.
 
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