Is there a requirement for a minimum distance between a buried 33 000 KV line and a natural gas line? If so what is this minimum distance? Where can further information be found on this subject?
I'm not sure where to find that requirement - maybe in the gas code. All NEC seems to say on the subject is this:
300.8 Installation of Conductors with Other Systems. Race‐ways or cable trays containing electrical conductors shall notcontain any pipe, tube, or equal for steam, water, air, gas, drain‐age, or any service other than electrical.
Since a trench doesn't meet the definition of a raceway, we can't use this section even though I believe that the intent is there. Incidentally, I tried changing this section in the last code cycle. Here is what I proposed that got shot down:
Public Input No. 1086-NFPA 70-2017
"Raceways, cable trays, or trenches containing electrical conductors shall not contain any pipe, tube, or equal for steam, water, air, gas, drainage, or any service other than electrical."
and this was my justification for the change:
Many electrical inspectors including myself tend to freak out when we encounter a trench that contains an electrical raceway or direct burial conductors - along with a pipe for water, or some other system. General Contractors just love to do this. There is nothing in the code to prevent this, as currently 300.8 is strictly limited to raceways and cable trays.
It could be very dangerous - should one of these other systems require servicing - that there be electrical in the same trench (or vice-versa).
Underground raceways or direct burial conductors should be in their own trench, in the event that wiring needs to be exposed (dug out) and the existing conductors repaired, tapped, or intercepted.
I've seen many engineered electrical drawings where the entire service was being relocated, and engineer will designate a point at which to dig and make splices, and provide written instruction on the plan and say something similar to this:
"Intercept service lateral (or feeder) at this location, splice using approved method, and route to new service location..."
This is very common. This practice of installing underground raceway or direct burial conductors in the same trench with other systems should not be allowed to continue, IMHO. I believe this would be a good change for Article 300.8.
The code panel stated this as a response:
Response Message: The submitter did not provide any technical substantiation that a problem exists. There have been many installations of underground electrical systems located on one side of a trench with water, sewer, and other systems located on the other side of a trench. Where underground service conductors are buried, 300.5(D) (3) requires a warning ribbon be placed in the trench at least 12 inches above the underground directly buried service conductors.
Naturally, I didn't provide substantiation that a problem exists because I'm trying to avoid having a problem exist. I'm trying to avoid having someone get hurt. And then they go on to mention "service conductors," even though this section applies to more than service conductors. So I guess if someone gets hurt or injured, then there will be technical substantiation that would satisfy the code panel. Please, if anyone out there knows of an accident that happened please contact me so we can resubmit the proposal for the 2023 National Electrical Code cycle. Thanks.
often times when trenching for the generator we have to pass under water or sprinkler or whatever. I really don't see how it can be avoided, but we always ran conduit for our power wires and some AHJs considered the Generator wire, which most commonly were #6 THHN or #4 THHN and 10% of the time would be 2/0 or 250 350 500 and 750 for some of the 100kw and 150kw
with my experience of doing Generac Generator installs for 4.5 years in Oklahoma, the AHJ has always required 6 inches of separation if the NG line and electrical conduit ran in the same ditch. One instance where they required 2 inches of concrete, but there were plenty of times they didn't care. The AHJ does not like for a gas line to pass under an electric service or panel. There was one instance in an older neighborhood where the gas for the 22kw generator had to pass under our electrical conduit and the AHJ WAS GOOD WITH THAT AS LONG AS THERE WERE NO JOINTS IN THE GAS LINE WHERE IT PASSED UNDER THE ELECTRICAL CONDUIT. HOPE THE TRADE KNOWLEDGE WAS HELPFUL
I know that for utilities, there is a minimum radial separation distance. But there isn't anything like that in NEC. Maybe a gas person can chime in and let us know about their code. This next go-round in the NEC, I may try for radial separation distance in the same trench. The code panel might approve that.
Yeah, had one plumber do the gas on 90% of our upward thousands of generator installs. pretty much had 4.5 years of experience of what the AHJ in many different places in Oklahoma that required 6 inches in the same ditch but one time in Edmond where we done hundreds of automatic Generac Generators, wanted concrete, but all the previous times it wasn't like that. I think it depends on the experience of the inspector. Some that weren't sure required more and some times just the interpretation of the paper work with the generator
Assuming this is a 33kv utility cable it will not be covered by the NEC. Different states use their own rules but majority are similar.
In California we have General orders which utilities must follow. GO 128 covers underground installations.
33.4 From Foreign Substructures. (Except Communication Systems)
a) Independently installed: Supply cables, when independently installed, shall be separated where practicable, from gas, water, oil, or other pipe systems, or other foreign substructures, by a clearance of a least 12 inches when paralleling and by at least 6 inches when crossing.
Check IEEE-C2 National Electric Safety Code. They deal specifically with utility electrical installation requirements. Part 3. Safety Rules for the Installation and Maintenance of Underground Electric Supply and Communication Lines has some guidance. They recommend a minimum distance of 12 inches, but you may want to read the standard more thoroughly to address 33 kV specifically.
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