This month we kicked off Project Shark. Project Shark is a business adventure that will explore, tear down, rebuild, process, construct, analyze, and grind in an effort to bring the best electrical engineering services to market for our customers and our team. Welcome to our journey!
“Trust is the glue of life. It’s the most essential ingredient in effective communication. It’s the foundational principle that holds all relationships.” Stephen Covey
Trust matters. Trust forms the basis of relationships in team environments and is an essential factor for design and construction teams, ownership, and other project stakeholders. During my career I have experienced both ends of the trust spectrum and points in between. In some cases parties are unknown entities far away and in other cases parties are fully engaged in the design and construction process.
Lack of trust has real consequences (including financial) in the decision making of project teams. Lack of trust can lead to inconsistent decisions, unclear priorities, redesign, over or under designing, and indifference.
Teams with strong relationships and trust communicate more effectively, come to better decisions, and have fewer unexpected outcomes. Trust allows parties to operate and make decisions with confidence in a swift, effective manner without having to stop and evaluate decisions and potential outcomes based on a host of real or perceived uncertainties.
Building trust is not always easy given the variables in human personalities and interactions. However, there are some fundamental things that can be done (by all project stakeholders) to build trust across teams. Do these six things to form a trust foundation to build from.
- Introduce (or introduce yourself to) key project stakeholders and get to know them.
- Communicate (or ask what are) key stakeholder objectives (schedule, quality, price points, etc).
- Handle contract matters efficiently and fairly (contracts, invoices, scope changes).
- Communicate regularly.
- Follow through on commitments.
- Take the time to say thank you (both directions) once the task is done.
Doing these regularly will communicate to other team members that you are engaged and sincere in your desire for positive project outcomes. These relatively small investments in time over the course of your project will pay dividends in many ways, and in many cases beyond the current work at hand.
– William Bethurum PE, Principal VoltaUS
Panelboards are found in nearly every building and facility type. They represent a significant element in power distribution systems and it is common for most professionals and non-professionals to come in contact with them regularly. Panelboards are covered by NEC Art. 408. The typical panelboard consists of the ‘can’, the ‘interior’ or bussing, and ‘circuit breakers.’ Panelboards can be found in ratings as high as 1200 amps and provide an excellent and compact means for distributing large quantities of feeders and branch circuits. There are some fundamental characteristics to be aware of when in design and during construction. Here is a brief look.
- Location: Ideally, locate panelboards as close as possible to the loads they feed and in a dedicated space such as an electrical room. For low voltage panels at 208/120V, locate panels to limit excessive branch circuit runs and associated voltage drop. Consider the analogy of a tree trunk (as the feeder) and the branches (as the branch circuits). In general you get better economies of power from the feeder than from individual branch circuits. Get those panels where you need them to limit branch lengths. However, remember to try to stay away from restrooms, janitor closets, and similar areas.
- Interrupting rating: Otherwise known as AIC or “amperes interrupting current” is a circuit breaker rating that indicates the maximum amount of current that the breaker can safely interrupt during a fault. The panel ‘AIC’ rating is that of the lowest rated device in the panel. Multiple breakers can combine to achieve a ‘series rated’ combination but that is a topic too involved for this discussion. Pro tip: AIC is a significant cost driver that shouldn’t be overlooked when estimating equipment costs.
- Accessories: Many panelboards can accommodate lighting controls, metering, surge protection, sub feed and feed through lugs. You might need or want these.
- Ratings: Of course this sounds obvious. Voltage, current, etc. However, make sure to match a 3 wire system to 3 wire panel and same for 4 wire system. A 3 wire system may function using a 4 wire panel but the code (and likely your inspector) wont permit it. Panelboards with three phase high leg systems require the high leg be marked per the NEC.
- Mounting: Flush or surface? Remember to provide at least a 6″ deep wall for flush mounting a standard sized panel which is typically 5-3/4″ deep. The ‘semi-flush option’ resulting from the panel sticking out 2 inches beyond the wall isn’t pretty and usually requires some trim out to help reduce the silly appearance.
- Enclosures: Various NEMA ratings are available. Indoors, NEMA 1. Outdoors, NEMA 3R. There are explosionproof panelboards and also corrosion resistant panelboards for locations such as marinas and chemical process areas. Many times it is not possible to keep the panels remote from the environment (see item 1 above) due to excessive distance.
- Height: Although not a common issue, the maximum breaker mounting height is 6′-7″ as per NEC Article 404.8. So, consider this when installing the taller varieties. Impress your friends at cocktail parties with that one.
- Branch circuits quantities: Since the 42 circuit rule was eliminated in recent code cycles, panelboards of the lighting and appliance type can have as many branch circuits as available from the manufacturer (in most cases) provided item #7 (above) is met. More often than not the panelboard runs out physical breaker space before ampacity. Being able to add additional breakers can provide some much needed flexibility. However, with all good things comes moderation. Pro tip: Always include spare breakers and/or prepared space when specifying new panels. Half of these will likely be used before the panel is ever put into service.
- Working clearance: 30″ width minimum is always required and can be measured from either side of the can. The voltage level and condition dictate the required depth in front of the panel (measured from the face) as outlined in NEC Article 110.26. For 208V systems 36″ is the maximum depth required. 480V systems require 36″, 42″, or 48″ depth depending on whether the area in front of panel is clear, has grounded system, or other live parts. There is also dedicated equipment space required above the panel within which no foreign systems are allowed. Refer to NEC Article 110.26 for some detailed explanations and nice diagrams (annotated version of the NEC).
- Arc flash, incident energy, and PPE (personal protective equipment): Arc flash warning labels are required by NEC. Detailed arc flash hazard analysis which includes incident energy, hazard level, and corresponding PPE provides the most appropriate information. After an arc flash hazard analysis is completed the corresponding hazard levels, identified on the arc flash labels, will alert a worker to the corresponding personal protective equipment that should be worn.
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This is a good article for the non electrical professional because it discusses the basic concepts in a concise manner and has some nice diagrams.
When designing manufacturing facilities the method of power distribution is a subject that comes up early and often. The one nearly universal requirement from the owner is flexibility to be able to accommodate changing power distribution needs due to changes in equipment and equipment locations. For those owners with specific long-term needs then underground distribution may be an option but I will neglect this option for this brief summary. I will also neglect large facilities using sub floors and interstitial spaces.
The (3) common choices are conduit, bus duct, and cable tray. All have been used successfully over the years and all have inherent advantages and disadvantages.
Lets start with traditional conduit systems. Distribution panels are typically located throughout the manufacturing floor or possibly in centralized locations. From that point the individual branch circuits are fed to the equipment in overhead conduit runs. Conduit is typically supported with unistrut trapeze systems.
Advantages: Simple to specify and install.
Disadvantages: Conduit and branch circuits can’t be reworked or reused without modifications to the conduit systems.
Next we have bus duct which is supported overhead, comes in various ratings through thousands of amps, and can be routed in different directions as needed. Fused switches or breakers are installed in the bus duct as plug-in modules and from those switches power is connected to equipment by cord or conduit runs.
Advantages: Provides large quantity of power above the manufacturing floor.
Disadvantages: High initial capital investment, high weight load, capacity often goes under utilized, poor choice in areas congested (or potential to be congested) with other systems, can’t be easily modified.
Lastly, we have cable tray which can be used to support power cables between the distribution panels and equipment. Cable tray comes in different materials (aluminum being common), widths, and configurations. Tray can be routed horizontally or vertically with offsets as needed.
Advantages: Light weight, can be routed fairly easily, size can be scaled up / down, tray cable can be routed from tray directly to equipment (with certain cable types), easy to re-route or add conductors as needs change, tray can be added if needed.
Disadvantages: Tray cable cost is higher than standard conductors, difficult to route in congested locations.
The choice of method will vary based on many factors. However, the most common factor I have found (unusually so) is simply owner preference. For open manufacturing floors I prefer cable tray for the advantages listed above. I prefer conduit for smaller or congested installations. I reserve bus duct for specific clients and needs. If making a selection for your project consult your engineer for a full evaluation of the different methods and the associated costs.
Yesterday I had the opportunity to evaluate the retrofit of traditional T8 fixtures with T8 LED lamps as part of a customer’s facility wide evaluation of lighting upgrades. Multiple similar locations were retrofit using products from multiple suppliers and 2 different technologies, one where T8 LED lamps (15-18W each) with integral driver replace existing lamps and another where each fixture is retrofit with lighting kit and separate LED driver. Fixtures being upgraded in the evaluation included traditional 3-lamp T8 acrylic lensed fixtures in a cleanroom application and the new technologies were selected after a preliminary cost evaluation was completed using simple payback. All of the technologies performed very well by reducing output power by roughly half while providing very good light output in our test cases (between 50 and 80 foot-candles). Some of the benefits of the replacement LED lamps in addition to the energy savings are the relatively low labor cost and long lamp life. Each installation is different (energy cost, light requirements, lighting controls, etc.). But, I would certainly recommend the evaluation of these technologies for anyone looking to upgrade current lighting technologies especially those with 24/7 operations. Lamps run between $22 and $25 each. Retrofit fixture kit costs vary.
Avoiding corrosion in electrical systems | Consulting-Specifying Engineer