Surface Routing MC-HL Cable

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Steve Merrick

Member
Location
Anchorage, AK
Our design engineering contractor is proposing surface routing a group of outdoor 480 volt MC-HL feeder cables along the top of the gravel pad at a remote industrial facility. This seems to me a violation of the 24 inch minimum cover requirement of Section 300.5(A). The engineer says the cables are not required to be buried or routed via cable tray because they will be protected by concrete jersey barriers and routed behind buildings.

Is this practice permitted?
 

Steve Merrick

Member
Location
Anchorage, AK
I agree, but it might be viewed as direct buried cable with 0 inches of cover.

I have never seen any other installation where permanently installed feeder cables are routed by strewing then along the ground with no cover or support.
 

iwire

Moderator
Staff member
Location
Massachusetts
I agree, but it might be viewed as direct buried cable with 0 inches of cover.

But that would be untrue, it was laid on the ground therefore 305 does not apply.

I have never seen any other installation where permanently installed feeder cables are routed by strewing then along the ground with no cover or support.

Securing it is required.
 

Steve Merrick

Member
Location
Anchorage, AK
Unburied MC-HL cable is not listed in the Article 330.10 Uses Permitted list, but neither is it listed in the Uses Not Permitted list in 330.12.

It seems unprofessional, but if there is no Code-based reason to require the cables to be either buried or installed in tray, I guess I will have to hold my nose and allow it.

Thanks for your responses.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
Section 330.10(A)(4) permits it to be exposed. The only caution is that it isn't subject to mechanical or chemical damage.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
I use plenty of MCHL. Your engineer covered 330.12(1), subject to physical damage

However, as Iwire said, it is required to be secured - 330.30 (A), (B), (C). One normal practice I have used is to secure to treated wood sleepers on 6' centers.

ice
 

Steve Merrick

Member
Location
Anchorage, AK
Section 330.10(A)(4) permits it to be exposed. The only caution is that it isn't subject to mechanical or chemical damage.

I interpret permissable "exposed" cable runs to be where they are supported by buildings or tray as permitted under 225.10, or where supported by messenger cable as allowed under 396.10; not just unreeled off the spool and left in the dirt.

Article 590.4(J) states, "Cable assemblies installed as branch circuits or feeders shall not be installed on the floor or on the ground." The fact that this practice is expressly forbidden for temporary installations makes me all the more uncomfortable to approve it for a permanent installation. Still, I can't find anything in the Code beyond the "neat and workmanlike" installation requirement or possibly Table 300.5 that would allow me to require prohibit ground-run cables for permanent installations.

Think of the Pandora's box this opens: I no longer have to bury any cables or use cable tray. By this interpretation, I must allow MC-HL cables to be run along the ground or piled on the floor so long as someone makes the subjective judgement call that the cables are not likely to be subject to physical damage. What a mess that will create.
 

iwire

Moderator
Staff member
Location
Massachusetts
I interpret permissable "exposed" cable runs to be where they are supported by buildings or tray as permitted under 225.10, or where supported by messenger cable as allowed under 396.10; not just unreeled off the spool and left in the dirt..

You are entitled to that opinion but the code sections do not back that up in the least.


Think of the Pandora's box this opens: I no longer have to bury any cables or use cable tray. By this interpretation, I must allow MC-HL cables to be run along the ground or piled on the floor so long as someone makes the subjective judgement call that the cables are not likely to be subject to physical damage. What a mess that will create

Yes, assuming they are secured that is exactly what the code would allow.

But the code is not a design or installation manual. That is why job specifications and requirements are vital if this sort of work offends the person paying the bills.



90.1 Purpose.
(A) Practical Safeguarding.
The purpose of this Code is
the practical safeguarding of persons and property from
hazards arising from the use of electricity.

(B) Adequacy. This Code contains provisions that are considered
necessary for safety. Compliance therewith and
proper maintenance results in an installation that is essentially
free from hazard but not necessarily efficient, convenient,
or adequate for good service or future expansion of
electrical use.

Informational Note: Hazards often occur because of overloading
of wiring systems by methods or usage not in conformity
with this Code. This occurs because initial wiring
did not provide for increases in the use of electricity. An
initial adequate installation and reasonable provisions for
system changes provide for future increases in the use of
electricity.


(C) Intention. This Code is not intended as a design specification
or an instruction manual for untrained persons.
 

rbalex

Moderator
Staff member
Location
Mission Viejo, CA
Occupation
Professional Electrical Engineer
I interpret permissable "exposed" cable runs to be where they are supported by buildings or tray as permitted under 225.10, or where supported by messenger cable as allowed under 396.10; not just unreeled off the spool and left in the dirt...
Exposed (as applied to wiring methods) is defined in Article 100:
On or attached to the surface or behind panels designed to allow access.
Technically, support, securing, and protection are issues covered by other Sections.
 

Steve Merrick

Member
Location
Anchorage, AK
Thanks, guys. I respect your input. I will let them build it as designed.

Meanwhile, we have many thousands of miles of MC-HL installed on our system - all neatly routed in cable tray or directly buried. As I don't want this installation to set a precedent, I will add words to our design and construction specifications to ensure our contractors don't start using the ground surface as an acceptable means of routing cable. Although it would be a huge cost savings to us if we do allow it.

- Steve
 
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