ASCE Substation Structure Design Guide

[structural-eng]

The ASCE substation structure design manual has its own load factors and combinations which are lower than the ASCE7/IBC. I understand why they are lower but I'm wondering what legal grounds an engineer has to use them since the document is a guide and not a code. We work for an electrical engineer and design the steel support structures and foundations for their substations. We just want to make sure that if there damage from a weather event that we're not drawings additional liability by using the reduced loads. I have tried reading both the IBC and a few state codes as well as the NEC and NESC and it's not clear to me which documents apply to substations.

 

[Lomarandil]

Short answer: you're fine.

Longer answer: it comes down to the scope and applicability of each standard. Just because ASCE or IBC publishes a standard doesn't make it the governing code for any given project. That happens when:
1) The document states that your project type is within its scope of intended use (side note, IBC's scope makes me laugh)
and
2) Some government agency (often in a local building code) states that projects of type X should conform to standard Y.

Sometimes 2) doesn't happen (especially in construction or industrial applications). In this case, your liability is typically limited to the prevailing standard of care provided by other reasonable and qualified engineers. For substations, this is where you fall -- there's a lot of precedent for using ASCE 113, and I've never heard of another code being legally required instead. (You should double check this with your specific client, but sounds like you already have looked into it).

I might be getting mixed up, but my memory was that NESC only applied to power structures outside the substation fence. (small caveat, we'd also use it for the deadend, since it saw loads from outside the fence).

 

[structural-eng]

Thank you for the response. I was under the same understanding you are. That ASCE 113 is THE design document to use. I also agree about NESC, it's for overhead lines outside the fence as well as the dead end because it is loaded by those lines. I was just having a hard time finding clear direction on whether substations fall under the IBC (which most states adopt).

 

[Lomarandil]

Technically, it may fall under IBC (I'm not an IBC expert by any means).

But I've never seen it done.

 

[SlideRuleEra]

Check with the electric utility. In some states, utilities are explicitly exempt by law from building codes and similar documents. They may have their own standards. These standards may, or may not exceed generic requirements. Depends on factors such as the importance of the service area the substation supports (e.g. hospitals, sewage treatment plants, essential industry, etc.).

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