NEC Clarances

[kingtutley]

I am looking for service entrance clearance requirements.

I have found the minimum vertical requirements above grade, stuctures etc. for the service conductors. (225.18, 225.19, 230.24 & 230.26)

I have also located MOST of the working space requirements for the meter socket (110.26)

What I canot find is a minimum vertical requirement above grade/decks/accessways etc. The max appears to be 6.5' based on 110.26.A.3 which defers to 110.26.E. There does not apear to be any mention of minimum vertical distance. I ask because meters are typically (based on what I have learned from the electricians where I work) installed between 4' and 6' from grade.

Can anyone point me to the NEC section(s) that define these distances?

 

[dpc]

What I canot find is a minimum vertical requirement above grade/decks/accessways etc.

Vertical requirement for what specifically?

I'm not clear on what you are looking for - the minimum vertical clearance to overhead service conductors?

The 6'-6" rule applies to the handles of disconnecting means such as circuit breakers and disconnect switches.

The meter base height requirement is set by the serving utility so it can be accessed and read.

 

[kingtutley]

I think you answered my question. I was asking about the clearances for the meter socket. I was told that the meter should be installed between 4' and 6' from grade. I could not find the reference to either in the code. I found that according to section 110.23(A)(3) that the height of working space should be 6.5' from grade. However, if the placement of the meter is determined by the utility and NOT by the NEC, then I have my answer.

Curious, though. The NEC specifies almost everything in such excruciating detail. Odd, in my opinion, they would not tackle this minor item.

 

[dpc]

It may be in the NEC somewhere, but I don't recall seeing it. It's not so minor to the utility, so maybe it makes sense to defer to them. The meter belongs to the utility.

 

[JLSeagull]

Check IEEE C2.

 

[dpc]

IEEE C2 = National Electrical Safety Code.

Good point, but the serving utility is free to adopt more stringent requirements. Also, the NESC is not strongly enforced in many states.

 

[JLSeagull]

Part 2—Overhead clearances. A new approach for calculating clearances is detailed in new Section 23 and
Appendix B. Rules related to sag calculation for conductor sags as related to clearances were moved from
Sections 25 and 26 (loading and strength) into sections covering clearances. All calculations in which both
loaded and unloaded conductors involving ice and wind when used for strength calculations remain in
Sections 25 and 26. Rule 215C2 was revised to require all guys regardless of exposure to be insulated or
grounded. Rules related to guy and span wire insulators moved from Rule 279 to Rule 215C2 to improve
subject matter retrieval from the Code. The vertical clearance of a service drop attached to a mast, porch,
deck, or balcony has been increased from 2.45 to 3 m (8 to 10 ft). Rule 235G has been changed to allow
multiplex line cable up to 750 V to attach to the same support bracket as neutral conductors meeting
Rule 230E1.

 

[rbulsara]

I would say meter socket is utility company's domain ask them or check their website. They usually have a booklet published for meter socket installation, etc.

Rafiq Bulsara

http://www.srengineersct.com

 

[rbulsara]

See the attached for an example of Northeast Utilities. Section 8 addresses meter installation and page 59 shows a picture..with some dimensions.

http://nuwnotes1.nu.com/apps/clp/clpwebcontent.nsf/AR/YellowBook/$File/yellowbook.pdf

Rafiq Bulsara

http://www.srengineersct.com

 

[kingtutley]

Right, yes. Thank you.I have been going back and forth among C2, NFPA70, NFPA70E and NFPA70H. I cannot find specific information for clearances from grade. Everything else, but not that. That's why I asked. It seems odd that they would go to such great lengths to identify all other variables, but omit that. Strange.

I will just follow what the electricians have said and leave it at that. Thanks for all the info.