Big Light Poles - UL Certification vs Structural Design

[hemiv]

I've got a project at a sports field which includes some 70' - 80' light poles. The electrical engineer spec'd Musco poles, and I have received some submittals from the contractor. In my specs, I asked for stamped pole shop drawings showing that they meet the project design criteria (I assumed this would be similar to, say, what you would get for pre-engineered wood trusses or metal buidlings).

However, the Musco rep seems confused by this and has only given me their UL certification and a warranty that states the poles were designed to project specs. They also provided the foundation design.

Do the UL certifications have anything to do with site-specific structures? Might understanding to this point has been "no". I feel like I need to take it with a grain of salt and still get some confirmation of engineering data, at least a max bending moment and shear capacity.

How have others dealt with structures like these? Its a gray area for products out there in the marketplace that we then have to be EOR for.

 

[milkshakelake]

I haven't done light poles specifically, but I have done industrial tanks and equipment. They come with loading information (usually down to 0 decimal precision, like 7754 lb on this support) in their submittals and they come with signed and sealed drawings. They generally have teams that do the stress analysis in PV Elite or some other software. Sometimes they come with ICC-ES certification, which is kind of a long process, and those documents would say what seismic loads it's designed for. I was involved with the ICC-ES certification for one of them, which was a modular conduit assembly for a power plant rated for some pretty insane seismic loads. I've also worked with modular stacks for power plants, which also come with signed and sealed drawings. Not exactly a light pole, but kind of similar.

I don't know how much help that is for light poles. But 70'-80' is quite substantial, and not something that I'd personally want to sign off with just a UL certification. From what I know, UL has more to do with electrical.

 

[BridgeSmith]

Some of our high mast light towers for highway projects all have sealed designs from the fabricator, if they designed them. When we specify all design information, such as the wall thicknesses, base plate thicknesses, size and type of welds, etc., I don't think they stamp anything.

If these poles are a standard manufactured item, there may be some 'loopholes' for that, but if they are a custom design for your project, they should be sealed by the person who completed the design. Depending on the state regulations, it may have to be specifically a structural PE, but clearly a failure of one of these could be a hazard to human life.

 

[hemiv]

msl - Your experience is similar to mine. I was expecting a few pages of shop drawings with details, design notes, reactions, and a stamp. My understanding of the UL is the same, more about broad conformance to electrical codes rather than specification conformance to site-specific design criteria. They do provide a warrant that the poles meet wind loads, but not seismic...and a warranty is not the same as a seal...

bmith - The poles are a standard item. I think the UL might have information on max shear and bending moment, so I have asked them for that at least.

 

[milkshakelake]

You also mentioned a foundation design. Does it give any info about what wind/seismic loads and subgrade capacity it's designed for? What I've seen for industrial stuff is a signed and sealed foundation plan that has a table for reinforcement and dimensions for different loading conditions, and which code it applies to (say ASCE 7-16).

 

[BrentG]

Musco designed the light poles at my children's high school in Canada. They were 70' high. Musco provided a 13 page structural calculation package (sealed by a PE from Iowa). We used his reactions to design the foundation.

 

[hemiv]

msl - Yes, that's what we have in hand. Although it's deficient - no mention of seismic loads.

brent - That's great to know, thanks for sharing. The SE we have on the foundation is from Iowa, so probably the same firm. Musco did tell me today that they are looking to get a me "calculations," so perhaps such a package is what they have in mind.