Service Drop Q

[alarsen1]

I just finished going through the Electrical Studies (excellent piece of work BTW!!! Thank you for this!!!) and found a possible discrepancy that I wanted to try and clear up. It's not a big deal as our service drop clearances in Canada are a little different than in the States - they are slightly higher; are Canadians taller?

According to the quiz a service drop over a swimming pool must be 22 1/2' above and 10' away horizontally... and the minimum service drop clearance over a flat roof is 10'. However, according to this diagram in some Carson Dunlap material I have, the numbers are different... 18' over a pool and 8' (min) over a flat roof. Which is correct?

[jbreazeale]

Arne, you're going to feel dumb when I tell you this, but in your diagram, the words at the top say "Service Drop Clearances (UNITED STATES)". What is correct is whatever Canada says is correct. The clearances in the diagram represent the minimum required in the IRC, and which is recognized as the minimum in the states. Ergo, the heights you quoted for Canada are correct for your jurisdiction. Sometimes, we can't see the forest for the trees, eh?

[alarsen1]

Originally Posted by jbreazeale

Arne, you're going to feel dumb when I tell you this, but in your diagram, the words at the top say "Service Drop Clearances (UNITED STATES)". What is correct is whatever Canada says is correct. The clearances in the diagram represent the minimum required in the IRC, and which is recognized as the minimum in the states. Ergo, the heights you quoted for Canada are correct for your jurisdiction. Sometimes, we can't see the forest for the trees, eh?

Let's just leave ourselves out of this for a moment lol... My question is one of curiosity; I know what the Canadian numbers are - (the differences in our service drop criteria being that we don't have a 3' minimum over a roof, rather, service drops OVER roofs are generally not allowed except by special permission; our clearances are higher over roadways & driveways; and we don't specify any criteria for running over swimming pools, probably because they are always frozen over... hee, hee). So... having said that...

I am comparing apples & apples and realize that my diagram is for the States, as it is immediately to the left of the diagram labelled for Canada in the same text book I have. I probably just didn't articulate myself very well the first time, but my question is, "Why is a US diagram different from this US-based quiz (from the NACHI website), as it pertains to these two service drop questions"?

The diagram depicts a minimum of 8' (8-10) over a roof, and 18' above a pool - whereas the quiz reads 10' and 22.5' respectively. Either the diagram that Carson Dunlap is using is wrong, or the quiz is. I'm just curious.

I went back to the quiz and copied & pasted the questions I am referring to below...

The minimum service drop clearance over a flat roof used as a roof garden should be?

10ft (correct)
12 ft
8 ft
18 ft


Service drops around a swimming pool should be?

12 ft above and 15 ft horizontally away from
10 ft above and 22 ft horizontally away from
22 1/2 ft above and 10 ft horizontally away from (correct)
18 ft above and 10 ft horizontally away from
15 ft above and 8 ft horizontally away from
10 ft above and 20 ft horizontally away from

[jbreazeale]

IC, sed the blind man...I really wasn't trying to be a smart **s, Marc, and apologize if you felt insulted. And I see the problem you are having now. A bit of ambiguity there, eh? They got swimmin pules in the Great White North? I thought you guys called them backyard hockey courts!

[jbreazeale]

I mean, Arne...not Marc....dang, time to go to bed!

[alarsen1]

Originally Posted by jbreazeale

I mean, Arne...not Marc....dang, time to go to bed!

LOL! No worries, and never once felt insulted. Cheers!

[alarsen1]

Originally Posted by jbreazeale

They got swimmin pules in the Great White North? I thought you guys called them backyard hockey courts!

You mean like this?

[Kenneth Lott]

Was'nt that picture in the quiz over a deck or roof garden?

[David P. Valley]

The question asks for minimum distance. So 8' should be the answer for the flat roof. But.... a garden adds a foot or two and it becomes a trick question. Dirt does have a height to it. So 10' would be the minimum distance.

[David P. Valley]

As for the pool, the answer should be 18 ft above and 10 ft horizontally.

"Click to Enlarge"
Attachment 9460

Note the diagram above also states that if the flat roof is a balcony (which a garden would be considered a balcony) the minimum distance must be 10 feet.

[Greg Fretwell]

680.8 says 22.5 feet above the water for overhead conductors 0-750v, 25' up to 15kv and 27' if it is over 15kv OR 10 away

[Paul W. Abernathy]

Yeah....you have to remember Carson Dunlops stuff is OLD...and I mean OLD....the NEC and Canadian codes change over time but once an image is made it is kinda DONE...unless someone updates it.....

The 22.5 is CURRENT standards.......and what you will see mostly with regard to dwellings...0-750V is well within what your dwelling will deal with in these clearances.

At one time it was lower...I believe the revision came between the 1999NEC and the 2002 NEC.....maybe the POOL poles got longer...who knows.