NEC 230.49 states ug service entrance conductors are to be protected against physical damage according to NEC 300.5. NEC 300.5 states "where the enclosure is subject to physical damage" use rigid metal, imc, or sch 80 pvc...to a point 8 ft above finished grade. Also restated in NEC 230.50. In NEC 300.50.....conductors emerging from ground shall be enclosed in listed raceways. Raceways on poles shall be rigid metal, imc, or sch 80.....to a point 8 ft above grade. What locations are subject to physical damage? 1.)utility poles / service poles 2.) service installations mounted on meter structure 3.) service installation mounted on 4.) service installation mounted on the side of a building
what se conductors are subject to physical damage
- Thread starter mike w
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pierre
Senior Member
- Location
- Westchester County, New York
Re: what se conductors are subject to physical damage
Subject (ive) to physical damage.
This is a subjective topic that can and is left up to the AHJ. All of the answers and none of the answers you receive here are correct.
The only good answer is from the individual inspecting the particular installation.
Subject (ive) to physical damage.
This is a subjective topic that can and is left up to the AHJ. All of the answers and none of the answers you receive here are correct.
The only good answer is from the individual inspecting the particular installation.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: what se conductors are subject to physical damage
There is a similarly subjective aspect of the "Rules of the Nautical Road." The rules tell each of two approaching vessels what to do, to avoid a collision. But the rules only apply if there is a risk of collision in the first place. If the closest the two vessels will get to each other is 20 miles, neither one is likely to take any evasive actions to avoid a collision, and they don't have to. The bottom line, however, is that if there is a collision, it is going to be hard to convince the court that the reason you did not maneuver to avoid a collision is that the rules did not apply, since you were not close enough for there to have been a risk of collision.
In your case, if a conductor does become damaged (causing, for example, a fire), you are going to have a hard time convincing the court that you did not have to protect the conductor because it was not "subject to damage."
There is a similarly subjective aspect of the "Rules of the Nautical Road." The rules tell each of two approaching vessels what to do, to avoid a collision. But the rules only apply if there is a risk of collision in the first place. If the closest the two vessels will get to each other is 20 miles, neither one is likely to take any evasive actions to avoid a collision, and they don't have to. The bottom line, however, is that if there is a collision, it is going to be hard to convince the court that the reason you did not maneuver to avoid a collision is that the rules did not apply, since you were not close enough for there to have been a risk of collision.
In your case, if a conductor does become damaged (causing, for example, a fire), you are going to have a hard time convincing the court that you did not have to protect the conductor because it was not "subject to damage."
- Location
- Massachusetts
Re: what se conductors are subject to physical damage
As much as what Charlie posted makes sense IMO it also leads us to the conclusion that everything is subject to physical damage.
I would say that is true but we can not wire like that, I can not use concrete reinforced RMC for every circuit. I agree with Pierre it is entirely subjective all you can do is use common sense and talk to the local inspector.
Personal I assume anything that comes up out of the ground or slab (exposed) is subject to physical damage and use RMC.
Edit in exposed.
[ September 21, 2005, 05:29 AM: Message edited by: iwire ]
As much as what Charlie posted makes sense IMO it also leads us to the conclusion that everything is subject to physical damage.
I would say that is true but we can not wire like that, I can not use concrete reinforced RMC for every circuit. I agree with Pierre it is entirely subjective all you can do is use common sense and talk to the local inspector.
Personal I assume anything that comes up out of the ground or slab (exposed) is subject to physical damage and use RMC.
Edit in exposed.
[ September 21, 2005, 05:29 AM: Message edited by: iwire ]
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: what se conductors are subject to physical damage
Lets keep in mind it's unfused hazard.
Lets keep in mind it's unfused hazard.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Re: what se conductors are subject to physical damage
Engineers have an unwarranted reputation for seeing things only in "black and white." That is not true. We see the gray. We know why it is gray, and how it got gray, and how gray it is, and how much gray we can tolerate before taking action to remove the gray.
That was not my intent. Rather, what I intended to convey is that we are going to be held responsible for the choices that we make. We can choose to leave something unprotected, if we feel it is not subject to physical damage. My point is that this should be a deliberate choice, one made with the understanding that we may be called in to explain why we made that choice. That is (IMHO) the single most essential element of an engineer's professional life.
Engineers have an unwarranted reputation for seeing things only in "black and white." That is not true. We see the gray. We know why it is gray, and how it got gray, and how gray it is, and how much gray we can tolerate before taking action to remove the gray.
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