The Mike Holt Podcast: Recent Episodes
Mike Holt
We’re committed to improving the electrical industry in every way we can. We strive to provide as much as we can to the industry at no charge. From industry publications to Mike Holt guides on key topics like Swimming Pools and Marinas, we provide an abundance of content to help you.
110.26 Working Space about Electrical Equipment – https://www.MikeHolt.com/code. Clearances and working space around electrical equipment are necessary to provide a safe working environment for electrical professionals. The rules that are in place to ensure this space is available are often misunderstood. Be sure you understand these requirements as we discuss Part II of Article 110 in the NEC; more specifically, section 110.26.
According to 110.3(B) in the NEC, equipment, including conductors, must be installed in accordance with the manufacturer’s instructions. But what about when the length of these conductors creates a voltage drop? Is voltage drop just a recommendation in the NEC and not really enforceable? Find out in this podcast where we discuss the ramifications of voltage drop in branch circuit and the energy and life safety issues that may be affected.
406.12 Tamper-Resistant Receptacles - https://www.MikeHolt.com/code. The locations where tamper-resistant receptacles are required have been greatly expanded in 406.12 to include all education facilities, areas where people are awaiting transportation, dormitory units, and assisted living facilities.
312.8 Splices in Panel Enclosures – https://www.MikeHolt.com/code. When it comes to electrical enclosures, “As long as we can get the cover on, we’re good.” is the mindset of many. The NEC has requirements for fill or how much space inside an enclosure is available for wiring and electrical devices as you’ll see when you listen to this podcast on section 312.8.
The 2020 Code cycle brought many changes to Article 690, Solar Photovoltaic (PV) Systems. Some of the more notable changes were in section 690.12 for "Rapid Shutdown" and are discussed in this podcast.
Do you know how a Grounding Electrode System works? What about grounding for PV Systems? Is a grounding system even required? The answers to these questions and more can be found in this podcast.
Bonding and Grounding of PV Equipment is a requirement in Section 690.43 of the NEC and references sections in Article 250. Find out how to ground the equipment and why it needs to be done!
If you've pulled wire into a raceway, you understand the reason to have limits on the wire fill for raceways. In this podcast, we’ll discuss the most common condition, where multiple conductors of the same size are installed together in a raceway and the maximum number of conductors permitted can be determined from the tables in Annex C.
230.67 Service Equipment Surge Protection - https://www.mikeholt.com/code. This new section requiring the installation of a surge-protective device (SPD) for all dwelling unit services has been a long time coming. Up until now, dwelling unit surge protection has been optional and usually an “extra” for the electrician. Section, 230.67, now requires surge protection for all dwelling unit services to protect sensitive life safety devices like smoke and CO detectors from surge damage.
230.71 Service Disconnects, Six Maximum – https://www.MikeHolt.com/code. When it comes to service disconnects, the rule of six movements of the hand is pretty well established but, can there ever be more than six? Just how does the NEC define a “service” and does this definition allow for more than six service disconnects? In this podcast on section 230.71, we discuss the requirements regarding the maximum number of service disconnects.
230.71 Service Disconnecting Means - https://www.MikeHolt.com/code. Although the rule of six grouped service disconnects didn’t change, disconnects are now required to be compartmentalized to reduce the hazards associated with arc-flash and arc-blast. This might not seem like a big change but, it makes most of the available multi-meter centers and switch boards ineligible for use to meet these requirements.
440.9 Rooftop Air-Conditioning Equipment Grounding Conductor – https://www.MikeHolt.com/code. You may already be aware that metal raceways such as RMC and EMT are suitable equipment grounding conductor types, but what about where roof-top air-conditioning equipment (roof-top units or RTUs) is concerned? Discover the unique requirements for RTUs in this podcast about section 440.9 in the NEC.
406.9(C) has redefined the bathtub or shower “zone” and prohibits the installation of receptacles in this area. Don’t worry, some latitude was added to the rule allowing for receptacles to be installed in bathrooms too small to meet these requirements.
406.(D)(2) Receptacle Replacement, Without Ground Wire – https://www.MikeHolt.com/code. So, you need to replace a receptacle and discover there’s no equipment ground. What are your options? What does the Code allow or require? The fact is that electricity has been coming into buildings for well over a century, and an equipment ground wasn’t always required. It’s only a matter of time before you come across this situation and listening to this podcast on section 406.4(D)(2) of the NEC will help you to know how to handle changing out a receptacle where there’s no equipment ground present
300.7 Raceways Exposed to Different Temperatures – https://www.MikeHolt.com/code. Where raceways are exposed to different temperatures, section 300.7 of the NEC requires us to take measures to prevent condensation inside the raceways. How this is accomplished, and when and where this rule applies, is the topic of this podcast.
352.44 PVC Expansion Fittings – https://www.MikeHolt.com/code. Who doesn’t like PVC? It’s versatile, lightweight, cost-effective, and easy to install. Did you know that raceways expand and contract to some degree and PVC does much more than RMC, IMC, or EMT? Although sometimes overlooked, expansion fittings are required to accommodate this characteristic and the requirements in section 352.44 of the NEC are the topic of this podcast.
90.1 Purpose of the NEC – https://www.MikeHolt.com/code. The National Electrical Code contains the rules and requirements for electrical installations, but why? What’s its true purpose? Find out in this podcast clip as we discuss Code section 90.1.
300.22 Plenum Space Wiring Methods – https://www.MikeHolt.com/code. Nowhere is the risk of the spread of fire more apparent than in the spaces and ductwork that distribute environmental air, or the ductwork that provides different types of exhaust. The types of ducts, plenums, and the special wiring and electrical installation considerations contained within section 300.22 of the NEC are the topics of this podcast.
404.2(C) Neutral at Switch Locations – https://www.MikeHolt.com/code. If you’re under the impression that all light switch locations are required to contain a neutral conductor, then you’ve been misinformed or maybe you haven’t read the Code. Learn the conditions where light switch locations may, or may not, require a neutral conductor in this podcast about section 404.2(C) in the NEC.
Motor circuits have special requirements that affect how the overcurrent protective device and conductors are sized and installed. So how do we size the conductors and protection? Motor full load current? Nameplate rating? What’s the difference? Find out in this podcast where we explain the motor full-load current ratings contained in Tables 430.248 and 430.250, and how they affect not only conductor sizing but also the overcurrent protection requirements of Table 430.52.
This podcast is an extract from Mike Holt’s Understanding the 2020 National Electrical Code Complete Training Library. For more information about this product visit https://www.MikeHolt.com/code or call 888.632.2633.
555.35(B) Marina and Boat Dock Leakage Current Measurement Device - https://www.MikeHolt.com/code. Electric shock drowning (ESD) is a frightening killer and anything that can be done to prevent it should be done. That is the intent of the change in 555.35(B) requiring a leakage current meter to be provided on site at docks and marinas to assist in the maintenance of shore power connections. This isn’t a solution to the problem but a commendable effort was made to keep the owners and users of docking facilities safe.
555.13 Marina and Boat Dock Bonding – https://www.MikeHolt.com/code. Increased awareness of the electric shock drowning hazards at docking facilities has prompted another group of changes in this Code cycle. New section 555.13 requires a bonding conductor from the panelboard to connect to all metal parts in contact with the water that are likely to become energized in and about boatyards, marinas.
When interconnected electrical power production sources, such as wind powered generators, solar PV systems, or fuel cells are connected in parallel with utility power, special considerations for safety and efficiency must be made. This makes supply-side source connections a most critical aspect of a safe and compliant installation. This podcast on Section 705.11 explains just what the requirements are to accomplish this.
Interconnected Electrical Power Production Systems Sources are connected in parallel with the serving utility with no transfer switch. There are complex requirements to install these systems safely and expert knowledge is required. Learn more about it in this podcast on section 705.13.
Anytime there is more than one source of power supplying a building, safety concerns arise. The rules for Interconnected Electrical Power Production Sources are contained in Article 705 in the NEC. Learn what is covered within this article in this podcast discussing the Scope of Article 705.
90.4 Inspector’s Authority – https://www.MikeHolt.com/code. The National Electrical Code is intended to be suitable for mandatory application by governmental bodies, but just who is responsible for ensuring the Code is followed once adopted? In this podcast on 90.4, we’ll explain what’s meant by the “authority having jurisdiction.”
Often referred to as "redundant grounding", equipment grounding requirements in patient care spaces utilize two different types of equipment grounding conductors so an installation error or component failure won't result in the loss of the effective ground-fault current path. Listen to this podcast to find out which wiring methods meet these NEC requirements.
Hazardous (Classified) Locations are unique because they have additional requirements when installing electrical equipment and circuits. But ? Find out how to identify these locations in this podcast.
250.30 Grounding, Transformers – https://www.MikeHolt.com/bonding. In order to comply with NEC 250.30, you first need to understand what is meant by a “separately derived system” then you will understand what is trying to be accomplished in these Code requirements covered in this podcast.
250.4 Grounding, System and Equipment – https://www.MikeHolt.com/bonding. In this podcast on the “General Requirements for Grounding and Bonding” we’ll discuss bonding and grounding of electrical systems and equipment and explain exactly why these terms have two entirely different meanings and why it is so important that you understand the purposes of the two. We’ll explain electrical system “grounding” and also equipment “bonding” which essentially means that any current-carrying conductive materials (metal) that are likely to become energized, be connected to an “effective ground-fault current path.
250.24 Grounding, Service Equipment – https://www.MikeHolt.com/bonding. Before you can understand the grounding of an electrical service and equipment, you’ll need to understand just what a “service” is. This podcast will explain that and where we go from there to ensure compliance with NEC 250.24.
250.6 Grounding, Objectionable Current – https://www.MikeHolt.com/bonding. What is “objectionable current”? What are it’s causes, can it be prevented and if so, how? In this podcast, we discuss why objectionable current is a dangerous condition and the NEC requirements that serve to mitigate its causes.
250.36 Grounding, High Impedance – https://www.MikeHolt.com/bonding. Did you know that a high impedance grounded ac system cannot serve line to neutral loads? In this podcast, we’ll explain what a high impedance grounded system is, where the impedance must be located, and how it differs from a conventional solidly grounded electrical system.
250.54 Grounding, Auxiliary Grounding Electrode – https://www.MikeHolt.com/bonding. Are auxiliary grounding electrodes required by the NEC? Do they serve any real purpose? The answer(s) is/are, no. Find out why and how they might just do more harm than good in this compelling discussion with our panel of experts!
250.53(A)(2) Ground Resistance Measurement – https://www.MikeHolt.com/bonding. NEC 250.53(A)(2) requires that a single grounding electrode be supplemented by an additional electrode but, is that always the case? Learn the exceptions as well as what qualifies as a supplemental electrode as our panel of experts discuss this topic.
210.8 GFCI Protection - https://www.Mikeholt.com/code. There’s no doubt that ground-fault circuit-interrupters have protected many people from electrical hazards. This Code cycle there is an increased emphasis on GFCI protection and many new locations that require GFCI protection have been added. The 2020 changes and revisions to this section are numerous and include clarifications, expansions to existing rules, and a few new items. Some rules were also relocated to and placed in more appropriate articles as indicated in the Informational Notes.
300.21 Fire-Rated Walls, Ceilings, and Floors – https://www.MikeHolt.com/code. Wherever there’s airflow, the potential for a fire to spread exists. The requirements in section 300.21 of the NEC are designed to prevent, as much as possible, increasing the spread of fire where electrical installations may decrease fire-resistive ratings of walls, ceilings, and floors. In this podcast, you’ll learn what must be done in order to comply with this rule.
A fire pump wouldn’t be of much use during a fire if the circuit conductors that supply it failed. Sizing these conductors isn’t the same as sizing other motor conductors. Listen to this podcast to ensure that you’re sizing fire pump circuit conductors correctly.
Service conductors supplying the entire load associated with a dwelling unit can be sized in accordance with Table 310.12 but are there any rules or considerations before using this table? What about if it’s a feeder instead? The answers to these and many other questions can be found by listening to this podcast on sizing these service/feeder conductors.
250.122 Equipment Grounding Conductor, Sizing – https://www.MikeHolt.com/bonding. The equipment grounding conductor sizes for 15A -30A circuits are easy to remember since they are required to be full sized and are part of cable assemblies. Larger circuits, however, typically require the use of Table 250.122 and that can be a little confusing. Listen to this podcast to better understand how these conductors are sized.
250.119 Equipment Grounding Conductor Types – https://www.MikeHolt.com/bonding. Equipment grounding conductors can be identified in several ways. In this video clip, we discuss how the NEC requires these conductors to be identified.
There is now so much sustainable electrical energy being produced that we need to find ways to store it! An Energy Storage System (ESS) consists of one or more components capable of storing electrical energy for future use. Article 706 in the NEC covers the requirements for ESS and it’s important to understand what Article 706 does and does not apply to. Find out why in this podcast on the Scope of Article 706.
For most of us, a loss of utility or normal electrical power is an inconvenience and is usually restored as soon as humanly possible. But where electrical power is essential for maintaining safety to human life, an emergency electrical system is required. Do you know what types of occupancies might require this consideration and who classifies these systems as emergency? To answer these questions and fully understand what distinguishes an ‘Emergency System’ from a ‘Backup System, read the attached text (paying particular attention the ‘Informational Note’) and listen to the podcast as me and a panel of experts explain.
For years, a common practice for one and two-family dwellings has been to install a meter enclosure outside and main breaker panel suitable for use as a service disconnect inside. As electrical professionals, many of us had that hunch to ask ourselves, "what about first responders." A recently added Code rule now requires an emergency disconnect for ALL one and two-family dwellings regardless of the panel's location indoors.
But what are the requirements of this new rule? Can the service disconnect act as an emergency disconnect, or does the emergency disconnect have to installed separately? How do we identify and distinguish between a service disconnect and an emergency disconnect?
Electric vehicles have been around for a long time. With bi-directional transfer of electrical power from your electric vehicle to your home becoming commonplace, the industry has had to adapt and the scope of Article 625 has changed again. Listen to this podcast to learn the scope of what’s covered in this article and what has changed since the last cycle.
250.122(F) EGC for Parallel Conductors, Sizing – https://www.MikeHolt.com/bonding. One of the costliest mistakes made in electrical installations is a failure to read and fully understand the Code rules for sizing and installing the EGC when paralleling conductors. Read your Code book while listening to this podcast and you could wind up saving yourself a huge amount of aggravation and money!
When three conductors are pulled into a raceway, they may flatten out creating a condition where the conductors could jam. In this podcast we’ll explain how to avoid this condition.
Factors that impact conductor sizing include not only conductor ampacity and equipment terminal temperature rating, but also the conductor insulation temperature rating. In this podcast we discuss Table 310.4(A) which provides information on conductor insulation properties such as letter type, maximum operating temperature, application, insulation, and outer cover properties.
To understand when to apply the requirements of Article 725 for remote-control and signaling circuits, you need to understand the Scope of this article. Listen to this podcast and discover what distinguishes “Class 1” from “Class 2” and “Class 3” circuits and what this article applies to.
210.4 Branch Circuit, Multiwire – https://www.MikeHolt.com/code. Multiwire branch circuits are an efficient and cost-effective approach to installing electrical circuits, but there are inherent hazards when this wiring method is used. In this podcast, we discuss how important it is for these circuits to be installed and serviced properly, and the consequences for failing to do so!
810.21 Bonding, Radio Antenna Grounding – https://www.MikeHolt.com/bonding. You may be surprised at the number of CB and HAM radio operators there are around the country. These radio frequencies require line-of-sight antenna which requires a substantial height (some are hundreds of feet tall) to maintain that line-of-sight. You can probably already figure out that these heights make them a prime target for lightning strikes. Watch this video clip to help you comply with the Code rules for grounding these antennae.
250.96 Bonding, Other Enclosures – https://www.MikeHolt.com/bonding. If you remember that the whole purpose of bonding is to establish an “effective ground-fault current path” in order to clear a fault, then you can better understand why proper bonding of enclosures and raceways is crucial in maintaining a safe electrical installation.
250.97 Bonding, Metal Raceways – https://www.MikeHolt.com/bonding. If you remember that the whole purpose of bonding is to establish an “effective ground-fault current path” in order to clear a fault, then you can better understand why proper bonding of raceways is crucial in maintaining a safe electrical installation.
250.94 Bonding, Communications Equipment – https://www.MikeHolt.com/bonding. Many believe that because of lower the operating voltages of communications systems, proper bonding of such systems is no big deal. That couldn’t be further from the truth! Find out why intersystem bonding and creating a “zero” potential is an important factor in a safe electrical system.
250.102 Bonding Jumper, Supply Side – https://www.MikeHolt.com/bonding. There are basic rules for supply-side bonding jumpers, find out just what those rules are in this video clip.
Mike Holt discusses Overvoltage Protectors with John Cavaroc, Ph.D., P.E. from Safe Laboratories and Engineering Corp.
110.16 Arc-Flash Hazard Warning Label – https://www.MikeHolt.com/code. What’s an arc-flash warning label? Where do these warnings need to appear? Who’s responsible for posting these warnings? The answers to these questions (and more) are discussed in this podcast on section 110.16 of the NEC.
The number of conductors in the same raceway that are carrying current can affect conductor ampacity, as can the ambient or surrounding temperature. In this video we’ll explain how to evaluate these factors to make the proper choice when sizing electrical conductors.
440.4(B) Air-Conditioning, Circuit Sizing – https://www.MikeHolt.com/code. The first time you’re called upon to size a conductor and overcurrent device for central air-conditioning and you look at the nameplate requirements that clearly state that a 10 AWG copper conductor and a 50A OCPD are required, it may contradict everything you’ve learned about small conductors. In fact, you may adamantly insist that 6 AWG is required by the Code and you’d be wrong! Learn why in this podcast on section 440.4(B) of the NEC.
Adjustable-speed drives can be variable-frequency speed drives(VFDs)—which refer to alternating-current drives only, or variable-speed drives (VSDs) which can be alternating-current or direct-current drives. Either of these can vary the speed of a motor, one by altering frequency and the other by adjusting voltage. But how does this affect the conductor sizing for the motor branch circuit? Does it even have an effect? Find out in this video on the topic of adjustable-speed drives.
In this podcast Mike Holt, Electrical Code Expert and President of Mike Holt Enterprises (www.mikeholt.com) shares the experiences, the struggles and the events that have shaped him, in addition to providing encouragement to others.