What materials are available to make a watertight penetration through the top of a concrete pull box for a vertical run of cable tray? In practice, is it preferable to use PVC conduit with rubber pipe sleeves?
I am on a team designing a substation layout. We are trying to achieve a compact, economical arrangement. It has been proposed that a 3-transformer bay (or more) layout could be achieved with a drive path around the equipment; imagine an oval track around a small sub. I think it could be...
The company I work for has a client on the West Coast with a phase-to-ground clearance violation. On a 115kV deadend structure, the inside phase of rigid auxiliary bus just slightly violates the 42" phase-to-ground clearance requirement to a switch vertical operating rod. This was just recently...
Fellow Structural Engineers - This is a call for help. For the past 13 years I have designed structures using hot rolled steel and reinforced concrete. I now find myself with a unique career opportunity working for a startup with the goal of designing modular building systems framed with light...
Do other structural engineers out there typically check the rebar shop drawings for a 3rd party contractor (different from in-house construction crew at a Design-Build or IPC firm) prior to construction? IMO, that is edging over the line of responsibilities. I have been doing this for an...
I've been doing a little work on the side recently and next year will have worked for others (owners/managers) for 15 years. I feel pretty good about my skill set and potential as a business owner. I'm thinking of making a leap of faith and try to develop my own consulting practice.
I have...
Questions for my EE brethren:
1. In a high voltage substation is it standard practice to run a ground conductor the entire length of cable trench?
2. In a high voltage substation are potential transformers typically bonded to the ground grid?
ACI 318 requires concrete cover to be 3" for concrete cast against and permanently exposed to earth OR 2" for concrete exposed to earth or weather (not cast against). I believe it could be argued that a void box (used to provide separation between bottom of concrete and expansive clays) acts...
I recently reviewed a cantilever retaining wall design. It occurred to me that the use of active soil pressure behind the wall is less conservative than using the at-rest soil pressure. Is this common practice? A model of the wall calculates a deflection of 1/16". It doesn't seem like this...
Quick question: in a broad sense, wouldn't it take a larger bar size for spiral reinforcement on a 6" pitch to equal the shear strength of a column with shear ties spaced at 6"?
Typically, shield (static) wires are considered to provide a 30 degree cone of protection on either side of the wire. Can this value be increased for shield wires running side-by-side, at the same height above grade?
Does ACI 318 require the 1% steel reinforcement (vertical rebar) that is referenced in LPile software for drilled concrete piers?
Also, if one tries to design the rebar for less than 0.95% the following warning appears: "This is permissible only if lateral geotechnical capacity is less than the...
Any old timers or neo-gurus have some rules of thumb for when it is really necessary to provide damping cable inside rigid pipe bus? Maybe some basic rules of practice based on maximum bus span and/or diameter of pipe. I have a little intuition on this but am looking for some feedback to support...
Anyone have knowledge of how frozen dirt may affect measurements of soil resistivity? We need work done in northern Colorado to design the ground grid for a new substation and it appears that some of our recent cold weather has frozen the soils down to about 30".
Christopher Renedo, P.E.
ESC...
Is it standard practice to ground both side rails of aluminum cable tray at support locations? I am designing cable tray that is carrying control cables from a new sub over to an old sub where there is an existing control house with available panel space. The cable tray is run vertically up to...
I work for a new start-up and we need to get software to help us with the grading design of some new HV substations. At my previous job with a large utility, the Autodesk suite was already in place to aid with this task. Now, I am responsible to help identify the best package for our needs...
For three years I worked with a large utility that has a complete library of standard structures. Everything is overdesigned so as to provide fool-proof reproduction of substation structures. There are no managers or supervisors with enough gumption to question the use of costly designs which...
