Wood "poll"

[sandsnow]

Proposition:

Common wood pole design with crossarms and bare conductors is not a specifically recognized NEC Chapter 3 wiring method and is therefore not permitted to be installed in a facility beyond the service point by the owner of the facility.

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Comment as you wish

I say false.

A 2x4 nailed between studs to support a box is not mentioned in the NEC. So the crossarms are ok in my view.

Table 310.21 covers ampacities for bare and covered conductors.

Section 225..14(B) sends you to 110.36 which talks about bare wire. You are then refered to 300.37 (as you mentioned) which again recognizes bare wires.

I think the second sentence of 90.4 gives an AHJ the means to accept the installation.

What does the voltage have to do with it? Nothing. I'm sure a lot of AHJ's are freaked out by real MV or HV but it is not rocket science.

 

[charlie]

Would the second to last sentence of Section 300.37 alter your analysis?

"In locations accessible to qualified persons only, exposed runs of Type MV cables, bare conductors, and bare busbars shall also be permitted." I gotta agree with that.

The most relevant to the poll is the FPN to Section 225.1.

This is what I based my first answer on.

Is there an on-line version of the National Electrical Safety Code?

Not that I am aware of at this time.

 

[charlie]

What does the voltage have to do with it? Nothing. I'm sure a lot of AHJ's are freaked out by real MV or HV but it is not rocket science.

Actually, it is rocket science when you have to take the ambient temperature, wind loading, icing (I live in a heavy loading district so I have to calculate 1/2" radial ice and 4 pounds of wind per sq. ft. on each conductor), placement of poles, the size and class of poles, the strength of guys and anchors, etc. into consideration when designing a pole line. Add a single communications circuit in the future and you have to start over.

All of the rules in the NESC are performance based so you don't have simple math and tables to go to for your answers. They do, in fact, need to be engineered and the local inspector does not have the expertise to inspect them. :smile:

 

[sandsnow]

Wouldn't the inspector be able to verify your design? I think it would be the same as a building inspector verifying beam size or footing depth. The design takes calculations that the inspector cannot perform, but he can sure read the plans.

Rocket Science was a bad choice of words. My bad.

 

[charlie]

Wouldn't the inspector be able to verify your design?

Not in my opinion. You would see a bunch of numbers that would probably be printed out from a spreadsheet but you wouldn't know if the formulas were correct or where the numbers came from. Additionally, you would not know if all the parameters were taken into consideration.

The bottom line is that you have to take a professional engineer's written statement with his seal that says he did it correctly. The engineer can say on the plans that a 50'-H1 pole is needed at this location but can you read the brand to know if the correct size and class of pole is actually used or know if it is set to the correct depth? If a 50M anchor is called for with 2-20M and 1-12.5M guy wires, can you tell if the proper lead was used, the correct size of guy wire, and the correct size of anchor installed? I would venture to say that you could not. This is not to say that you are a poor inspector but that you are not experienced in line construction and are not familiar with the rules that are in the NESC.

A professional engineer needs to sign off on this type of installation to show you that it is installed correctly.

Rocket Science was a bad choice of words. My bad.

To my mind, that is no big deal and not really a bad choice of words. After all, everyone knows exactly what you meant. :grin:

 

[rbalex]

Charlie,

As I mentioned in earlier correspondence with you, California does have a more prescriptive document published by the California PUC. (GO-95) The NESC is still a primary reference document.

For those of you who may be wondering, I am not the ?well qualified designer? mentioned elsewhere.

 

[charlie]

As I mentioned in earlier correspondence with you, California does have a more prescriptive document published by the California PUC. (GO-95) The NESC is still a primary reference document.

Sorry, I knew that but I keep forgetting. It is just like the Indiana Electrical Code and I always refer to the National Electrical Code. The difference is that the California version is a complete rewrite if I am not mistaken. :-?

 

[rbalex]

The current California Electrical Code is the 2005 NEC with California supplementary material from various adopting agencies. It is a rewrite in the sense that it is published as a complete document with the additional material annotated within the body of the text. The content differences are generally minimal. Local jursidictions may also have supplements with approval of the California Building Standards Commission.

My understanding is that the origins of GO-95 and the NESC were 1911 and 1913 respectively. Both documents have been seen various sponsoring organizations over the years.

 

[sandsnow]

The bottom line is that you have to take a professional engineer's written statement with his seal that says he did it correctly. The engineer can say on the plans that a 50'-H1 pole is needed at this location but can you read the brand to know if the correct size and class of pole is actually used or know if it is set to the correct depth? If a 50M anchor is called for with 2-20M and 1-12.5M guy wires, can you tell if the proper lead was used, the correct size of guy wire, and the correct size of anchor installed? I would venture to say that you could not. This is not to say that you are a poor inspector but that you are not experienced in line construction and are not familiar with the rules that are in the NESC.

A professional engineer needs to sign off on this type of installation to show you that it is installed correctly.



To my mind, that is no big deal and not really a bad choice of words. After all, everyone knows exactly what you meant. :grin:

I would be willing to accept an engineers statement that the system was installed correctly. There is already precedent for that in the building code for the structural engineer to visit the building in various stages to verify compliance with his design.

Again a poor choice of words on my part with regards to verify the design. Yes your calcs would be greek to me, but the pole spec, depth and guy size would not be beyond me. If I did not know how differentiate between poles or guy sizes, I would make it my mission to learn about the subject. As you say I have no idea at the moment what you are talking about except in a general sense. A 12.5M guy wire.....???? I thought it was measured in inches!!!

 

[steve066]

I would say false for most cases. The NEC normally deals with premisis wiring systems. And bare conductors spanning poles are normally used more for "between premisis" wiring systems - they are used to span large distances.

Now if Joe Blow wants to run bare overhead conductors on poles between his house and garage, then I think the NEC applies, and then it is not allowed. It is not allowed because in addition to being a premisis wiring system, it also doesn't have restricted access.

 

[charlie]

. . . I would make it my mission to learn about the subject.

I absolutely believe you would. :smile:

50'-H1 pole means 50 foot long and class H1 is the strength of the pole to handle the transverse loading (perpendicular to the line). You can tell the setting depth by looking at the brand. The brand is normally a set distance from the butt and it depends on the length of the pole. The brand will tell you the type of wood the pole is made of, the treatment, the manufacturer of the pole, the size, and the class.

A 50M anchor is rated for 50,000 pounds of pullout strength.

20M and 12.5M guy wires are rated for 20,000 and 12,500 pounds of strength.