ECN Forum Forums Code Related Discussion NEC & other Code issues 225-19a

[QUOTE]Originally posted by Scott35:
[B]Side note to: Don'tKnowEverythingYet,

Have you been trying to send me E-Mail in the last week or so??

No, I took your suggestion and posted to the group instead and look what I started! I have a whole folder of priest and nun jokes. Pope jokes too!
Although I did get one serious reply, I still don't quite get it. I get sorta nervous before I punch a hole in somebody's roof. It just seems that if Edison picks the location , and the mast is plumb and level, there is no way to be wrong. The only thing you can control is the height. So where is the 8' measured between?
Thank you, moderator!
BB

My jokes were my way of saying that I didn't understand it either!

I had opened the ol' NEC after reading your first post in this thread, and became just as confused...




[This message has been edited by sparky66wv (edited 05-11-2001).]

don'tknow;

you can 'read into' or 'read out' quite a lot in many codes, the intent is easily confused if related and/or compared to certain other sections.

my 2 cnts;

225-19a echoes 230-24b, same animal. you may hit your mast from any direction, as long as it maintains a minimum clearance from the roof.

the 'vertical clearance in all directions' is the usual expletive deletive, oxymoronic , double negative NEC lingo.

that said, i must go find my roseary beads

Let's look at an example of what I think the Code is talking about. Let's say you have a service cable from the local power company that swings from the pole on the edge of the property to a conduit mast not on the edge of the residence, but more toward the center. The drop is then down to the service entrance panel below. The service conductors that cross the roof top must be at least 8 feet above the roof surface. This is so that when the roof is being replaced, the roofers will not get into the service conductors and get themselves hurt or killed.
Enjoy reading the post on this site, but don't participate very often.
Thanks to all that do contribute.

Measure from the lowest point on the conductors to the roof surface directly below that point. That plumb line must be the center of a cylinder of the required height into which the conductors do not intrude.

If the roof slope is less than 4 in 12 or the voltage between the conductors exceed 300 volts the conductors must clear the roof by eight feet.
If the roof slope is 4 in 12 or greater and the voltage between conductors does not exceed 300 volts then the conductors must clear the roof by 3 feet when measured above the interior of the building or 18 inches when measured above the overhanging portion of the roof i.e. the soffit. If you use the eighteen inch exception the portion of the conductors length above the roof must be less than 6 feet long and must span a distance across the overhanging portion of the roof of four foot or less. Did I manage to make it any clearer.
--
Tom
225-19. Clearances from Buildings for Conductors of Not Over 600 Volts, Nominal.
(a) Above Roofs. Overhead spans of open conductors and open multiconductor cables shall have a vertical clearance of not less than 8 ft (2.44 m) above the roof surface. The vertical clearance above the roof level shall be maintained for a distance not less than 3 ft (914 mm) in all directions from the edge of the roof.
Exception No. 1: The area above a roof surface subject to pedestrian or vehicular traffic shall have a vertical clearance from the roof surface in accordance with the clearance requirements of Section 225-18.
Exception No. 2: Where the voltage between conductors does not exceed 300 and the roof has a slope of not less than 4 in. (102 mm) in 12 in. (305 mm), a reduction in clearance to 3 ft (914 mm) shall be permitted.
Exception No. 3: Where the voltage between conductors does not exceed 300, a reduction in clearance above only the overhanging portion of the roof to not less than 18 in. (457 mm) shall be permitted if (1) not more than 6 ft (1.83 m) of the conductors, 4 ft (1.22 m) horizontally, pass above the roof overhang, and (2) they are terminated at a through-the-roof raceway or approved support.
Exception No. 4: The requirement for maintaining the vertical clearance 3 ft (914 mm) from the edge of the roof shall not apply to the final conductor span where the conductors are attached to the side of a building.

that'd be the one Tom!

AMEN!