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LP and Electrical conduit, common trench?

JBI

JBI

Registered User
Joined
Oct 17, 2009
Messages
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Location
The Empire State
Not sure if I should post this here or the Gas page...

A question came up n the office today, can an LP gas supply pipe be in a common trench with an electrical conduit?

If yes,what separation distance would e required?

If no, please cite the appropriate section of the Code/Standard.
 
Nothing in NFPA 58 or 70....Our POCO wants 3 feet from the meter to the vent on a regulator (NG or LP), but nothing that I can enforce...It might be a bad idea, but not my concern...
 
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JBI,

I am assuming your office conversation was referring to underground

Service Conductors installed in conduit.

That said, as a matter of common sense, I would not want both

type systems installed in the same trench.......Just something about

gas and electricity not mixing well together.

In the `08 NEC, ...Article 300.5©(3) requires a warning ribbon to

be installed a minimum of 12" above the underground installation,

when the conduit is installed 18" or more below grade.........I'm

thinking that a minimum of 12" of separation from other systems

might be [ loosely ] interpreted as some sort of requirement

for general protection.

What say you ?



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north star,

That's a pretty big stretch... from a warning ribbon to reduce the likelihood of damaging the line to an implied separation requirement? Not sure I could hang my hat on that one. Though if they are in the same trench, I suppose the electric line could serve as the tracer wire for a plastic gas line. :-O
 
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I DID say loosely interpreted!.......Also, if not separation distance between

systems, which one do you want to damage first, ...your choice!

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JBI,

I got to thinking some more about your office conversation.

Assuming the LP gas line your are referring to is plastic, an

electrical tracer line is required to be installed

[ RE: Section 404.17.3, `12 IFGC ]........If the gas line is

installed in the same trench with electrical conduit, detection

of the 2 individual systems could be \ might be a problem.

I have asked some colleagues about installing 2 types of utilities

in to one trench.....The concensus is that it is not good practice,

nor would it be meeting the intent of Section 101.3 - Intent

[ `12 IBC ] in establishing the "minimum" requirements to

safeguard the public health, safety and general welfare through

safety to life and property from fire and other hazards.



While the various codes do not address every single application

out in the built environment, ...I believe that Section 101.3

allows the Code Official to make a determination of what they

deem safe and unsafe.........Some may agree while others may

disagree.......Essentially, it would be an AHJ call.

If it were my call to make, I would say No, ...do not install in the

same trench, unless there is adequate separation and

identification between the systems being installed.

Hope this helps !

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I would think a separation is more important that number of trenches.

I can dig an 18" trench a lay the pipes on each side of the trench, or dig 2 6" wide trenches 6 inches apart.

Which would you prefer?

Brent
 
Utility Shares its Underground Gas and Electric Separation Solution

http://www.utilityproducts.com/articles/print/volume-16/issue-06/product-focus/wire-cable-fiber-optics/utility-shares-its-underground-gas-and-electric-separation-solution.html

inno_joint-trench-1.jpg
 
AFAIK there is no code requiring a different trench for gas and electric. It may not be the best practice however it is allowed. If anything there may be something in the gas code but it is not in the NEC
 
north star said:
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In the `08 NEC, ...Article 300.5©(3) requires a warning ribbon to

be installed a minimum of 12" above the underground installation,

when the conduit is installed 18" or more below grade.........
Click to expand...
Just as a matter of clarification that art says nothing about conduit. Says "service conductors".
 
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"Just as a matter of clarification that art says nothing about conduit. Says "service conductors".
Click to expand...
You are correct sir !.....Totally my mistake..........I apologize forthe incorrect code reference..........Table 300.5 is the Table to

use for underground installations.

I believe that the "intent" of Table 300.5 is to prevent damage

to the underground conductors, whether they are encased in

concrete, ...some type of approved raceway, or the minimum

burial depths specified, ...they all have a "protection zone"

[ if you will ].

I would still want adequate separation of the different

systems installed; along with the approved type of warning

ribbon, or inside conduit, and tracer wire.

Now let's play the devil's advocate for a moment...

QUESTION # 1: You are the code official, and one of

these projects comes across your desk, ...what are you

going to allow for the install ?

QUESTION # 2: You are a homeowner, and this type of

project is planned for your property, ...what are you going

to allow \ want ?

You are aware of TABLE 300.5 [ in the NEC ], ...Section

101.3 [ in the IBC ], and Section R101.3 [ in the IRC ].

How do plan to protect the public welfare, or as a

homeowner, ...your own property ?.........If there is nothing

specific, and [ typically ] it is not good practice, ...what

is your decision ?



+ = = +
 
north star said:
+ = = +

I would still want adequate separation of the different

systems installed; along with the approved type of warning

ribbon, or inside conduit, and tracer wire.
Click to expand...
Someone once sang--- You can't always get what you want.....



Now let's play the devil's advocate for a moment...QUESTION # 1: You are the code official, and one of

these projects comes across your desk, ...what are you

going to allow for the install ?
Click to expand...
I don't believe you have a choice but to allow it unless you can site a code violation



QUESTION # 2: You are a homeowner, and this type ofproject is planned for your property, ...what are you going

to allow \ want ?
Click to expand...
If they are willing to pay then we will do what they want

 
Dennis said:
Someone once sang--- You can't always get what you want.....I don't believe you have a choice but to allow it unless you can site a code violation
Click to expand...
I don't see a whole lot of reason to separate gas pipe and conduit by much. If the concern is gas getting in the conduit and migrating to the house resulting in an explosion, the conduit is supposed to be sealed where it emerges from underground. At least I think that's the case for service laterals. I encountered a flooded building that had an unsealed underground conduit from a utility company vault. The vault was uphill from the building and it flooded.

Well back to what Dennis said. It's a rare contractor that would balk at separating gas pipe and electrical conduit if asked to do so. Seldom does anyone ask for a code section. I usually say that I will get back to you with that....and rarely do. Sometimes there isn't a code to back me up. So in order to treat everyone the same {the mantra of government officials everywhere} I endeavor not to provide code sections. If I did, I would have to make up a code for when there is none. Shirley we can agree, that is not allowed. ;-)
 
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The POCO and gas supplier here require separation of a foot apart even when they do trenchless installation with the available technology. Notice this popular brand of HDPE gas piping and neutral conductor appear similar;



 
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