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Kiribanda, Thanks. These arresters were not selected be me. I will have to ask the EPC Contractor who is responsible for integrating this into the existing substation. This Contractor is also the original designer of the Substation. I will have to ask them the question. Unfortunately, I came...

Hello, I was recently brought into a project that involves installing a new piece of electrical equipment into an existing substation. The new equipment (a harmonic filter bank) is being installed on the 24.9kV of the substation. The substation is located at ~7150 feet above sea-level and...

Thanks dpc. I agree with your assessment. Unfortunately, there's no traditional AHJ on this very unique project. Regardless of the situation, if I had been responsible for the design, I would've put a second exit in the room on opposite sides of the gear regardless of the rating. Unfortunately...

I have a question related to NEC 110.26(C)(2) and an existing electrical MCC room installation. The installation has an MCC with a 1200AF main incoming circuit breaker (CB) that is set at 800AT. The MCC is labeled and rated 1200A but set to trip at 800A. The upstream CB feeding this MCC main...

Thanks waross and FacEngrPE. I know this will fly in the face of everything you know but there is NO traditional AHJ on this project. I understand...makes no sense but that is the reality. This is not a traditional utility or IPP building this small facility. Unfortunately, we currently have...

I've been in the industry for some time and the only application where I've personally seen these t-body connectors used are in xfmrs, but I know they can be used in switchgear. Your picture showing the t-body connectors suggests very limited space for the terminations. A traditional bolted...

I have a question regarding a fire pump/motor and associated fire pump controller/auto-transfer switch (ATS) installation at small power generation plant (<40MW). The plant is in the final stages of installation and commissioning has already begun. Note the owner of the plant is not a utility...

Che12345 and Waross, thanks for your feedback. Understood. I've never seen only one (1) ground-grid riser connection to a MVSG bus in my 25+ years. Thus the reason for my question. One important point I need to make is that I'm coming into this project very late as an "observer". I in no way...

Hello, Have a question about a line-up of medium voltage (MV) switchgear. This is one of longer line-up's of gear I've encountered in my career measuring almost 40' in length. The main bus is rated 15kV, 2000A, 25kA, 3PH-3W and consists of seven (7) feeder breakers from very small generators and...

Thanks cdafd. Understood. I need to take a deeper dive into NFPA 850. Yes - the building of a wall (or in this case extending one) would be the correct choice. Unfortunately, there's some challenges associated with that. Again, I appreciate all your feedback.

Thanks cdafd. Appreciate the feedback. Yes the project is in the U.S. Also, thanks for the link...I've seen this before. My question is ultimately related to NFPA 850 (Recommended Practice for Fire Protection for Electric Generating Plants…) Chapter 5 (General Plant Design) section 5.1.4...

Hello, I have a question regarding the NFPA definition of a structure. I know in the 2017 Code the definition of a "Structure" was changed. The definition now states "That which is built or constructed, other than equipment. (CMP-1)". They added the reference to equipment for clarity. I am...

Thanks Swinny. I don't have any experience with domed pads but I understand what you're saying and in many applications would be ideal. I whole-heartedly agree the much tighter tolerances you mentioned are very easy to achieve and 2.5" is unacceptable. I've seen alot in my 30 years in the...

SlideRuleEra, thanks for your reply. I sincerely appreciate the info and the technical reference you provided. Good stuff. TigerGuy, great question. Some electrical equipment OEMs specify a maximum slope/angle their gear can be placed on. Prior to posting my question, I did look in the OEM...

Hello folks, I'm an power systems electrical engineer and have a concrete related question. Not sure if this is best posted here in the Civil or in the Structural forum. I'm working on a new project that involves the installation of two (2) small dry-type transformers rated 1500kVA. Each one...

Thanks jghrist, waross, and 7anoter4. As you can see, this issue is troubling me. If I had been involved in the initial design (or for that matter any of you), we wouldn't be involved in this conundrum. The "wild-card" in this whole situation is that the duct-banks were NOT installed in...

Hello waross. For various reasons, our meeting with the EPC contractor hasn't happened yet. You, Davidbeach, jghrist, bacon4life, and 7anoter4 have given me much to consider as I prepare for the eventual discussions. In the meantime, I have an important follow-up question for you. I specifically...

Thanks 7anoter4. After your post, I now see that this minimum clearance between ducts is an industry standard thing. Just about every UG ductback specification I've seen online refers to this. Thanks for the clarification and opening my eyes. Now it all makes sense.

Thanks waross. Agreed on the paint. This is a violation of NEC 250.12 and just common sense. I'm old-school and like exothermic welded connections but where bolting is allowed and utilized, I prefer class 2 stainless steel bolting hardware.

This is a continuation of a recent thread I started but I decided to post this question separately because I felt like it stood on its own I am either missing something obvious or misinterrupting the Code in this regard. NEC Figure 310.60(C)(3) for detail 2 (3 electrical ducts) and detail 3 (6...