I am investigating an incident in which a failure, resulting in a fire, occurred at a 480/277V, three-phase, four-wire panelboard. I do not know the causation of the failure at this time, however, I know that arcing occurred at some point due to the presence of irregularly-shaped openings along...
A house is supplied with a 240/120-volt, single-phase, three-wire service. No other houses are connected to the utility transformer's secondary side. The property owner is alleging that their phase-to-phase voltage rose to between 270 and 280 volts, resulting in the failure of numerous items...
Elevator manufacturer A has indicated that their elevator controllers have an SCCR of 5,000A, with no options for a higher SCCR.
Elevator manufacturer B has indicated that their elevator controllers have an SCCR of 10,000A, with greater SCCRs (14,000A at 600V, 25,000A at 480V, and 45,000A at...
In a few days, I will be performing an inspection at a property that reportedly suffered from phase loss, followed by damage to three-phase HVAC equipment. At this time, I'm not sure if damages involve air handling units, condensing units, packaged rooftop units, chillers, pumps, or a...
In a few days, I will be inspecting two HVAC chillers. They are arranged in an n+1 configuration in which only one chiller operates at a time. They are estimated to be approximately 15 years old. I do not know if the chillers are located outdoors or indoors. With respect to the VFDs, I do not...
A mechanical engineer presented to me a specification sheet of a 2.5MW, medium-voltage, natural gas generator. The engine appears to be turbocharged and combustion is classified as "low emission." He is interested in the temperature of the exhaust gases as a function of load. The specification...
I will be performing an inspection at a residential property next week. The electrical service is 240/120-volt, single-phase, three-wire, 60Hz. It is equipped with a 60kW, whole-house, standby generator and a 13kW PV system. The PV system connects to a loadcenter/panel via a grid-tie inverter...
A 240/120V, three-phase, four-wire, delta high-leg system comprised of three (closed delta) pole-mounted transformers serves two commercial properties. One of the transformers presumably failed, resulting in the opening of its primary-side fuse cutout. Both properties allegedly suffered from...
In a few days, I will be performing a forensic inspection of a PV system at a residential property. It was installed 12 to 18 months ago. The power production data of each panel is accessible by both the homeowner and the contractor who installed the system, which leads me to believe that a...
I am involved in a project in which an existing building is being stripped and renovated in its entirety. Its incoming utility service is 480V, corner-grounded delta.
As the project is presently designed, we are stepping this down to 208/120Y and serving all of the building's loads via the...
After nearly 17 years in consulting engineering, I am almost certain that I would like to make a career change into forensic engineering. Getting out of the office, performing investigations, using instruments and tools, writing reports, and, in my case, determining how or why something may have...
Using SKM PowerTools, I was performing a load flow analysis on a project to ensure that voltage drop levels were being kept to a maximum of 3% at panelboards and switchboards. (My state's energy code requires that it be kept to a maximum of 5% at the end load, and our goal is to distribute it...
A well pump equipped with a 230V, single-phase, 1.5 HP, PSC motor with a nominal full-load current of 9A is being controlled through a VFD. Upon startup of the pump, it immediately draws approximately 18A (Allegedly measured by the electrical contractor at both the line-side and the load-side of...
I'll be sitting for the Power PE exam in two weeks, and I just read the following claim (From http://engineerboards.com/index.php?/topic/27218-cut-scores/, if it's of interest to anyone):
Just heard back from a buddy on the NCEES Power Society, said the exam is harder this time because the pass...
I'm working on a project that contains an indoor diesel generator installation whose space constraints are less than ideal, to put it lightly. Upon comparing generators from two different manufacturers with seemingly identical ratings and performance characteristics (Same kW/kVA ratings, same...
I'm working on a project in which the mechanical engineer is locating VFDs, each one serving a roughly 10 to 15 HP pump, in an outdoor equipment yard adjacent to each associated pump. Knowing that VFDs don't fare well in high temperature, high humidity environments (The project is located in the...
I work for a somewhat large MEP (Mechanical, electrical, plumbing/piping) consulting firm in the United States and we're having what I perceive to be as an incredibly difficult time filling the numerous open positions that we have available. I may be completely wrong about this, but I don't...
So, last year, I graduated with a BSEE. I have a little over 10 years working in MEP consulting and I would love to do this for the duration of my career. I won't be eligible to take the PE exam for another 2 to 3 years, however, I fully intend to take it once I am.
My university recently...
So, I just purchased a 100 foot extension cord and was shocked to see that its packing had the California Proposition 65 warning label regarding lead content. It advised that you wash your hands immediately after handling the cord. The cord obviously doesn't contain solder, so where would lead...
Upon receiving an RFI from a contractor regarding Class A, Style 7 wiring requirements for a particular fire protection device, I researched NFPA 72 (2013 edition) and discovered that, much to my surprise, circuit styles have been completely eliminated. Fire alarm circuits are now defined by...
