Service Height in1975

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Re: Service Height in1975

Assuming the service drop is owned and maintained by the electric utility, you need to as them what their rules were at that time. They may require more than the NESC rules and the NEC rules in 230.24 (230-24 then) do not cover this installation.

For what it is worth, the NESC requires 12 ft with some footnotes to the table for triplex cable to a dwelling over areas that are accessible only to pedestrian traffic. Where conditions do not permit 12 ft, a reduction of up to 2 ft is permitted. :D
 
Re: Service Height in1975

I'll assume that 1975 is the year in question, and that the Code in effect was still the 1971.
1971 NEC 230-24 Clearance of Service Drops.
(b) Clearance from Ground.
Service-drop conductors when not in excess of 600 volts, shall have the following minimum clearance from ground. </font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">10 feet - above finished grade, sidewalks or from any platform or projection from which they might be reached;</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">12 feet - over residential driveways and commercial areas such as parking lots and drive-in establishments not subject to truck traffic;</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">15 feet - over commercial areas, parking lots, agricultural or other areas subject to truck traffic;</font>
  • <font size="2" face="Verdana, Helvetica, sans-serif">18 feet - over public streets, alleys, roads and driveways on other than residential property.</font>
<font size="2" face="Verdana, Helvetica, sans-serif">
 
Re: Service Height in1975

Al, out of nothing but curiosity, why do you think the 75 cycle (not that it changes anything) was not in effect?

Roger
 
Re: Service Height in1975

Hi Roger,

The generation of the next NEC after the 1971 was a four year cycle. The 1975 was released to us in the Fall of 1974 and then adopted by localities after that release.

I don't have 1975 NEC adoption history at my fingertips, but I recall that it was much like it is now. . .Most jurisdictions will adopt within a year, but some will take much longer, a few not at all.

As I compare '71 & '75 230-24(b) they are word for word identical. I guess this is what covers most of the bases.
 
Re: Service Height in1975

Posted by Charlie:
Where conditions do not permit 12 ft, a reduction of up to 2 ft is permitted.
Charlie,

In your experience, if the electrical contractor mounts the point of attachment so the low point of the catenary is 10' above the residential back yard, does that constitute "conditions" not permitting 12' ?
 
Re: Service Height in1975

Al, there are/were a lot of single story homes where 12 ft could not be obtained because of the type of construction. A footnote to the tables permitted a reduction of up to 2 ft for those situations. For years, the NEC has said in 230.24 that 10 ft is all that was required for service drops and some electric utilities took that as the norm without seeing what the NESC had to say about the subject. We require a 13? ft attachment point to permit us to get the 12 ft of clearance across the back yard and we will permit a reduction if the home will not permit the full 13? ft. So, to answer your question, if it is possible to get the height, we will require it to be met. :D
 
Re: Service Height in1975

Hello Al, thanks for the reply, I just wondered.

The 75 NEC was the first code book I purchased during my career.

Roger
 
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