Question 1. I have a question on 110.26(A)(E) [NEC 2002]. The minimum working clearances in 110.26(A) are not required if the equipment is such that it is not likely to require examination, adjustment, servicing, or maintenance while energized (see commentary in NEC 2002 Handbook). Does this also apply to the headroom in 110.26(E)? In other words, if the equipment is not likely to require examination, adjustment, servicing, or maintenance while energized, can the minimum headroom be less than 2.0 m (6 1/2 ft)? — R.D. Answer 1. Section 110.26(A), Working Space, tells us, without exceptions, that we have to follow the rules in 110.26(A)(1), (2), and (3) or as required or permitted elsewhere in this Code. Section 110.26(E), Headroom, tells us that the minimum headroom about service equipment, switchboards, panelboards or motor control centers shall be 2.0 m (6 1/2 ft) without reference to whether or not it may be energized. Where the equipment exceeds 2.0 m (6 1/2 ft.) in height, the minimum headroom shall not be less than the height of the equipment. The section has one exception to the minimum headroom rules and that is for existing dwelling units where the service equipment or panelboards do not exceed 200 amperes. The headroom in these cases shall be permitted to be less than 2.0 m (6 1/2 ft.). The statement you made in your question referred to the commentary in the 2002 NEC Handbook. While the commentary is very helpful at times, and is provided by the authors of that book, you have to remember that it is only commentary and not legal code words or content. The Handbook is an excellent publication to help users understand some of the Code’s more difficult areas. While the authors are very knowledgeable and provide a lot of excellent explanations, you have to realize that it is only their opinion and not Code. To summarize, you cannot apply your rationale using the 2002 NEC Handbook unless your jurisdiction has adopted and accepted the commentary in it. Without that, you would have to comply with the headroom and height requirements given in Section 110.26(A) and (E). —Russell J. Helmick Jr., CMP-1 | Return to top | Question 2. How do you calculate the available short-circuit fault current of a given circuit to properly size the OCPD and conductors to comply with 110.9 and 110.10? — G.C. Answer 2. First, to size your OCPD devices and the conductor sizes, you would use Article 220 [NEC 2002] to calculate the load to be used in the proposed building. Once you have that information, you would want to know what size transformer the serving utility would supply and its location in relation to the building service location. With that information, you would then use the regular short-circuit calculations to figure the available fault current or the point-to-point method. There are also some computer programs available when more precise calculations are necessary. Note: Usually this calculation is performed by the electrical engineer during the design process, or at times they call the serving utility company and get the available fault current values for the area in which the project is being installed and design for that current. Refer to pages 422–425 in Ferm’s Fast Finder for general information regarding the point-to-point method used to calculate the available short-circuit current. — Russ Helmick, Jr., CMP-1 | Return to top | Question 3. As home inspector, I am in search of information on double tapping on circuit breakers. I would like to know your position on double tapping. If the breaker is not designed for it necessarily, yet the correct AWG wiring for the assigned breaker is used and the total ampacity of circuit is used, is it permissible to double tap a breaker? I am taking the position that it is simply the lazy approach and there should be a single breaker for each hot lead tapped to the bus on a main panel — simple as that, but I am not an electrician. Can you give me your insight and posture on double tapping a breaker? —M.M. Answer 3. I will try to go through the Code so that it will, hopefully, be easier to follow. First, we would go to 110.3(A)(5) where the Code talks of heating effects under normal and abnormal conditions. Then take a look at 110.3(B), where it tells us that we shall use all listed and labeled equipment in accordance with any instructions included in the listing or labeling. Section 110.8 states that only wiring methods recognized as suitable shall be permitted to be used. Section 110.14 states that terminals for more than one conductor shall be so identified. Also, we would take into consideration 110.14(C)(1)(a)(1), where it talks about the temperature limitations on the connections. Finish up with 240.1 FPN which gives some information on the temperature problems, but 240.20(A) tells us that the overcurrent device shall be connected in series with each ungrounded conductor, which is really the main Code rule against applying more than one conductor under a lug on a circuit breaker. In conclusion, and in my opinion, the practice of putting more than one wire under a terminal on a circuit breaker is not allowed unless the circuit breaker is listed for more than one as stated back in 110.3(B). — Russ Helmick, CMP-1 | Return to top | Question 4. I have a question regarding whirlpool wiring. I have been installing 20-amp circuits for whirlpools. My Jacuzzi tub has the following label: "for all units: motor/pump: 115 vac, 3450 rpm/7.8 amp, 60 hz Single phase. electrical service requirements: 115 vac, 15 amp, 60 hz. Requires dedicated separate circuit." If a whirlpool is wired using a dedicated 20-amp circuit and I plug a Jacuzzi brand into this receptacle outlet am I violating the NEC? Assume proper GFCI protection. I see nothing in the above manufacturer’s specs that limit me to a 15-amp circuit. Also from Jacuzzi: "Depending on the model of the whirlpool bath, the installation/operation manual specifies which units must be 15-amp versus 20-amp GFCI protected. Since the model number or name of the unit was not listed in this email, you’ll need to look at the specifications sheet to determine which is needed for your installation. It is clearly stated at the bottom of the page on each spec sheet. If we require a 15-amp set up, we certainly do not want the unit installed on a 20-amp breaker and, yes, putting a 15-amp required unit on a 20-amp service can cause issues with the unit." Now with this response from Jacuzzi, I am concerned that others and I may be creating or allowing a safety hazard to exist. In the above specs should I read that as: At least a 15-amp Only a 15-amp Or not more than a 15-amp What am I able to enforce regarding this type of installation? If no whirlpool is present at the time of inspection, I have to pass this installation. If a Jacuzzi tub is present, am I required to fail this installation? — M.P. Answer 4. First, we should note that a whirlpool bath is a hydromassage bathtub as defined in NEC 680. Article 680, Part VII, provides specific code requirements for hydromassage bathtubs. Section 680.71 addresses protection of hydromassage bathtubs and associated electrical components and requires that they be ground-fault circuit-interrupter protected. Obviously, there is no mention of overcurrent protection in this section. Therefore, this may be a good point to note that NEC chapters 1 through 4 apply to all electrical installations and chapter 6 supplements or modifies those requirements. Knowing this, we now have an avenue to answer the questions on overcurrent protection. Your first question is in relation to a 20-ampere rated branch circuit supplying 15-ampere rated hydromassage bathtub equipment. Your question asks, "Am I violating the NEC?" If the hydromassage equipment manufacturer’s installation instructions indicate a separate dedicated 15-ampere branch circuit, and a 20-ampere branch circuit is installed, then, yes, it is a violation of the NEC. This is assuming that the hydromassage bathtub has a listing and labeling from a qualified testing laboratory. If so, 110.3(B), Installation and Use, is applicable to the equipment.If the equipment indicates a 15-ampere overcurrent device, then only a 15-ampere device is acceptable. In addition, we should note that 430.7(D)(1), Multimotor and Combination-Load Equipment, may be applicable too. This section requires that the equipment be marked with "the maximum ampere rating of the circuit short-circuit and ground-fault protective device." Also, take note of 430.42(C), Cord-and-Plug Connected, motors on branch circuits. This section allows individual motor overload protection to be omitted if the rating of the attachment plug and receptacle do not exceed 15 amperes at 125 volts.Your second question can be answered as follows: Based on the manufacturer’s information provided, the branch circuit must be 15 amperes. Although something less than 15 amperes may provide sufficient protection for the motor, it may eventually cause nuisance tripping of the overcurrent device. Realistically, why one would consider something less than 15 amperes is difficult to understand. Anything greater than 15 amperes is a violation.The third and fourth questions we have answered. The listing and labeling of the equipment, the manufacturer’s installation instructions, and minimum code requirements must be followed. If the installation of the hydromassage bathtub does not comply with these requirements, then the installation would not be code compliant. Unfortunately, you are in a predicament that many code enforcement officials find themselves in—enforcing minimum Code and ensuring a safe and code-compliant installation! I hope this information provides some guidance in your enforcement practice. — Lanny McMahill, CMP-1 | Return to top | Question 5. I wrote a code violation on these heat pumps at a local hotel based on NEC 110.26: the access to equipment considering the blocked doors by the condensate drains. My supervisor and co-electrical inspector immediately went out to the hotel and overturned my correction because the contractor complained that he only installed 265 of these and my correction would be too costly. Would you consider this correction a valid Code call? — D. B. Answer 5. First, it is difficult to provide a reasonable answer to the question based on the limited information provided; therefore, it is appropriate to qualify any answer and only respond in general terms.  Generally, Section 110.26 (NEC 2002) requires that "Sufficient access and working space shall be provided and maintained about all electric equipment to permit ready and safe operation and maintenance of such equipment." (Note: sufficient being adequate, enough or what is needed without being in excess). This requirement applies to all electrical equipment—see NEC definition of equipment—requiring operation and maintenance. With this in mind, it is reasonable to conclude that a 1600-ampere service entrance section (SES) with six disconnecting means requires sufficient access and working space for operation and maintenance. It could also be reasonable to conclude that a 20-ampere rated dwelling wall switch requires sufficient access and working space too. However, that is perhaps over and above the intent of the Code where practical safeguarding of persons and property comes into play. Subsection 110.26(A) specifically states that working space requirements are required where the electrical equipment is "likely to require examination, adjustment, servicing, or maintenance while energized." Subsection 110.26(A) provides for minimum depth, width, and height of the working space—the depth based on one of three conditions noted in Table 110.26(A)(1). Considering practical safeguarding, this requirement obviously applies to the 1600-ampere SES, but does not apply to the 20-ampere rated wall switch. One electrical equipment is "likely to require examination, adjustment, servicing, or maintenance while energized" and the other is not. Where does this lead us regarding heat pumps? Heat pumps are electrical equipment (appliances), so generally sufficient access and working space is required for operation and maintenance. Are heat pumps "likely to require examination, adjustment, servicing, or maintenance while energized?" One could venture to say no; yet, practical experience demonstrates otherwise. Heat pumps are typically energized during servicing for maintenance, testing, and repair purpose. The electrical and mechanical aspects of the equipment simply require this. Since the electrical equipment is "likely to require examination, adjustment, servicing, or maintenance while energized," the working space requirements of 110.26(A) should apply. As stated earlier, it is appropriate to qualify any answer; therefore, the word should was specifically used, as each electrical equipment installation must be evaluated on its own merits.  As always, reason, common sense and logic must be taken into consideration to assure a safe and Code compliant installation! — Lanny McMahill, CMP-1 | Return to top | Question 6. When are twin circuit breakers legal to use in a panelboard? Does the panelboard need to be listed for application? Do the panel cover and directory need to be listed? — M.V. Answer 6. First, we should clarify the term twin circuit breaker, which is a standard full size (single-pole frame) circuit breaker that incorporates two overcurrent devices, each switched independently. The overcurrent devices connect to the same ungrounded phase bus in the panelboard. Twin circuit breakers are typically limited to 120/240 volt, 15 and 20 amperes, and 10,000 amperes interrupting capacity. Twin circuit breakers are also known as dual, tandem, piggyback and two-pole thin. As an aside, there are single-pole overcurrent devices that are half the width of a standard full size single-pole circuit breaker. The single-pole devices are known as half size and single-pole thin. Twin circuit breakers are legal for use in panelboards if used and installed per the manufacturer's instructions and minimum code requirements. The panelboard should be marked to indicate the acceptable use and installation of these circuit breakers. A panelboard may bear the marking of 8-16 circuit, meaning any combination of eight twin circuit breakers or sixteen full size circuit breakers. The panelboard and/or circuit breaker may have a mechanical feature to limit the use and installation of twin circuit breakers to specific panelboards too. From a Code standpoint, 408.15 limits the number of overcurrent devices on a lighting and appliance panelboard to 42. This section also requires that "A lighting and appliance branch-circuit panelboard shall be provided with physical means to prevent the installation of more overcurrent devices than that number for which the panelboard was designed rated, and approved." A panelboard marked as Class CTL is a circuit-limiting panelboard that meets the requirements of this section. As a general rule, all electrical equipment and materials should be listed and labeled for the application as it would be difficult or impossible to determine the suitability of electrical equipment and materials for use and installation without listing and labeling. Naturally, most installations require the use of various passive devices, such as nuts, bolts, washers, straps, and so forth. These passive devices can easily be determined as acceptable for use and installation without listing and labeling. This usually requires some simple common sense. I hope this provides a reasonable response to your questions. However, I would encourage you to contact the appropriate manufacturer's representative as he or she may have more specific information and possible limitations on the use and installation of twin circuit breakers.— Lanny McMahill, CMP-1 | Return to top | Question 7. Recently I ran into a temporary power (diesel generator) company. In their portable power distribution equipment, they used a mix of single pole connectors (camlok) and pin and sleeve type connectors. My question is that the P&S connectors were “CeeForm” in nature. European rated connectors of 32A, 63A, 125A. As I understand it, the rating on these is for European voltages, 380–400 3-phase.  As such, if they are using the connectors for North American voltages, would they connector have to be de-rated accordingly, literally in 1/2 of the amperages they are listed for? Further to this, since I could not find a UL or other recognized testing facility stamp on the connectors, only a CE mark, are they permissible to use at all?  None of the connectors had any NEMA marks that I could see either. — G.L. Answer 7. Great question, and hopefully I can provide a reasonable response.  CeeForm is a European configuration connector that is widely used in Europe for the connection of power loads.  As you have noted, European connectors are available in 16, 32, 63 and 125 ampere (international) ratings, and single and three-phase configurations.  The connectors typically have what is known as an Ingress protection (IP) rating, such as IP67.  The IP rating is intended to provide information (guidance) on the appropriate use of the connector, such as for protection against shock, protection against penetration of solid matter and protection against harmful effects of water. Although I am not familiar with how the ampere ratings of the CeeForm connectors are determined, generally there should be no need to reduce the ratings for use on North American voltage systems.  If the connector is applied within its ampere and voltage rating, there should be no major concerns.  For example, a 63 ampere, 380 volt rated connector should perform just fine on a 60 ampere, 208/120 volt rated circuit - the circuit rating does not exceed the connector rating. Naturally, listed and labeled electrical equipment should always be used and installed!  If the CeeForm connectors bear a CE mark, most likely they are self-certified.  Self-certification (self-declaration) of electrical products is a standard practice in the European communities.  Therefore, determination on the approval and use of the connectors is a decision of the authority having jurisdiction. It should be noted that listed and labeled pin and sleeve connectors are available for use on North American Voltage systems.  Naturally, the listing and labeling provides reasonable assurance that the connectors are acceptable for use in accordance with the National Electrical Code.  Listing and labeling is also an indication that the connectors meet minimum safety standards. — Lanny McMahill, CMP-1 | Return to top | Question 8. Can you clarify a question that we have about the intent and application of 110.16?  Should the labeling be applied to all equipment identified in 110.16 regardless of installation date (does this article grandfather existing equipment) or does it apply to new installations only?  I have interpreted that the label should be applied to any panel that requires any task listed regardless of how old the equipment is or when it was installed. The arc-flash danger is there when the panel is opened. — R.W. Answer 8. National Electrical Code (NEC) Section 110.16 applies to “Flash Protection.” The intent of this section is to require “Flash Protection” marking on specific electrical equipment.  The marking is to warn qualified persons working on such equipment, while energized, of possible arc-flash hazards. The marking requirement is only applicable to “switchboards, panelboards, industrial control panels, meter socket enclosures, and motor control centers” in other than dwelling occupancies Section 110.16 does not establish an effective date for enforcement of this section; therefore, enforcement is mandatory upon adoption of the code requirement by the authority having jurisdiction.  Existing installations in compliance with the NEC at the time of installation typically can continue as is without the need to comply with current code.  As a note, there are requirements to bring existing installations up to current code, such as for the replacement of receptacles as noted in section 406.3(D)(2). Although the NEC does not use the word grandfather, it does use the word existing.  “Existing” is not defined in the NEC, but the word usually comes into play for replacement of equipment, for load calculations or for fine print note warnings.  The word “grandfather” tends to imply “to permit or continue.”  Obviously, if an electrical installation were considered unsafe, it would not be wise to grandfather it. Generally, it is difficult to clarify your question, as it is somewhat dependent on the jurisdiction or agency enforcing the code. Codes are typically adopted by jurisdictions with an effective enforcement date. Any electrical installation installed on or after the effective date would need to comply with the adopted code requirements. Since most jurisdictions do not mandate retroactive code requirements, enforcement usually applies to new installations.  Anything installed before the effective enforcement date is subject to the code requirements in effect at that time. Keep in mind that the arc-flash hazard is a work practice issue and warning signs will not ensure a qualified persons safety!  Only proper training, experience and understanding of the hazard involved will do that.  Where a possible arc-flash hazard exists, the marking of electrical equipment that is likely to require “examination, adjustment, servicing, or maintenance” while energized is a reasonable consideration.  Warning signs may get one's attention, yet undoubtedly they have nothing to do with a good and safe work practice!  As a closing point, this may be a good opportunity to emphasize the importance of the NEC definition of qualified person too. — Lanny McMahill, CMP-1 — More CMP-1 questions — The views of the authors of Focus on the Code and the editor are provided solely as a public service.  The views expressed are not the official position of NFPA, the NEC Correlating Committee or any of its panels, IAEI, IAEI News, or the author's employers. Nor are they intended to represent a formal or informal interpretation of the NEC.

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