Douglas Hansen

New Zealand has the right idea about cats. My sister's dog once went crazy barking at the back fence, jumping up along it, running back and forth to the door to get her attention. My sister finally goes around the block to the house behind her, and the elderly woman there has fallen down and couldn't get up. The dog knew. If my sister didn't have a dog, and that elderly woman had a cat, the cat would have waited until she died and then eaten her.

There are limits to what one can learn from a strictly visual inspection of a pool. To really know if everything is working properly requires operating the pumps, timers, heaters, etc. I once did a home inspection where the pool equipment house had dried blood and brains all over the place. The pool inspector made a fatal error in the settings of his valves as he attempted to test the backwash, resulting in a pressure buildup and subsequent explosion that drove the valve piston through his face. I saw that as a reinforcement of my decision to limit my pool inspections and exclude operation of equipment, other than the pool light. A visual inspection usually finds enough low-hanging fruit in terms of defects, be it corrosion, leaks, lack of GFCIs, barrier issues, cracks, etc, to keep you busy. Around here, pools don't really add value - some folks like them, more often they fill them in after purchase.

In our jurisdiction, the architect or contractor files all the paperwork, and included in that will be a form signed by the owner stating that the contractor has their authorization. I am not surprised by the zoning violations that are also mentioned in the article. An area of single family homes is going to be overwhelmed by the number of vehicles and transient residents (secret service agents) using the property.

With cable systems you can re-identify white wires to be used as ungrounded (hot) conductors. Aside from panels, this happens all the time with switch legs. With conduit systems you must pull the correct color if it is #6 or smaller. Black conductors #4 or larger in conduit can be taped at their ends to show that they are neutrals. Since your friend is primarily a commercial electrician, he doesn't use cable systems and it isn't surprising for him to be unfamiliar with these rules. They can be found in 200.6 and 200.7 of the NEC.

The UL standard for AFCIs now includes testing with GFCIs in the circuit. In first generation AFCIs, GFCIs did cause nuisance tripping in some brands. These problems have been resolved. There are also dual function AFCI-GFCI breakers for most brands now.

In our part of the world, NFPA codes and ICC codes work together fairly well. I haven't ever seen a non-federal jurisdiction use NFPA's life safety code in lieu of the ICC material that covers that subject. The only NFPA code that California directly adopts is the National Electrical Code. Some of the other NFPA codes and standards are adopted through their reference in an ICC code, and other NFPA codes might be used for guidance in gray areas (particularly mechanical design). The IAPMO codes make up the third leg of the tripod, and these can be a problem. There are many ways in which they are not compatible with ICC codes. More to the point of your article, they are also highly competitive with ICC in terms of product evaluation and certification. I also see a big difference between projects constructed using prescriptive codes (primarily single-family residential) and those that require design. Once design is required, ASCE 7 becomes the primary source document, and the local code is simply the door it walks through to be legally empowered as the basis for design.

Royal Institute of Chartered Surveyors http://www.rics.org/us/

This generalization might be a bit broad. The NEC requires a listing on some, not all, components of an electrical system. For instance, metallic wireways and auxiliary gutters don't require listing, whereas nonmetallic gutters and wireways do require listing. Motors don't have a UL listing, and luminaires weren't required to be listed until the 2008 edition of the NEC. To the topic at hand here, I once saw a Murray panel that had a specific list of the breaker model numbers that were acceptable in that panel. The contractor had a Murray breaker that was not on that list, and a close examination of the breaker jaws showed that it only seated about 50% of the area of the jaws on the bus stab. Sometimes even the correct brand is still not the correct model. Home inspectors often see older panels with no labels or instructions, and in such cases do not have a sufficient amount of information for certainty about the compatibility of the breakers and the panel.

A friend is remodeling his pool house to turn it into an art studio for his wife. It is in the smoky mountains, near the North Carolina / South Carolina border. It's a simple gable roof structure with no attic space. The rafters are 2X10s and there will be 6 inches of insulation in the rafter bays. The climate includes some freezing and snowfall, and in the summer months is hot and humid. Heating and cooling of the space will be from a ductless mini-split, and realistically there will be long periods of time in both winter and summer when it won't be turned on at all. Should he install a ridge vent? Should he supplement that with vent strips near the eave to provide cross-circulation through each rafter bay? Or should he skip the idea of ventilation altogether? Thanks

If the motive for replacing the panel is to have something that is accepting of AFCIs, you wouldn't want to choose a Square D product. They don't make a 2-pole AFCI, so they aren't compatible with multiwire circuits, which almost every house contains. Because Square D doesn't make a breaker that will work with them, they advise against using multiwire circuits, as seen on pages 4 & 5 of this document. I have no doubt they would sing a different tune if they did make a breaker compatible with multiwire circuits, such as those made by Siemens and Eaton.

Thanks, Marc, I should have said shocked or burned. IMO, the Inspectapedia comment is not incorrect. He says there that if an arc jumps to a person, the AFCI will detect that arc and we assume it will then trip - shock prevention, no? I have no idea why the Canadian authorities chose bedroom circuits only for AFCI protection, but I imagine they have studied historical events to make their decisions. The idea that an AFCI detects an arc to a person is nonsense. First off, the detection mechanism of an AFCI is that it looks for a repeating pattern of voltage drop and current spikes that are the signature of an arc, and that is not something that would be possible using a human as one of the conductors. Second, AFCIs do have a GFCI function, albeit at a higher level of current than would qualify them as class A GFCIs, but which certainly be activated before any possible detection of a repeating arc to human skin. As to the reasoning on first requiring them for bedroom circuits, there was no historical track record to support the idea that any one area needed them more than somewhere else. The reason for their gradual rollout was to get the products developed and working. They are a technology that was driven by the codes, not a code requirement that derived from actuarial data. The code-making-panel in the 1999 NEC stated that they had to start somewhere and arbitrarily chose bedroom receptacle outlet circuits. The first generation of AFCIs were essentially beta-tested on the general public, and the second generation of "combination" AFCIs incorporated a great many fixes to the flaws and limitations of the first generation. The 2017 NEC culminates that process with a requirement that they be installed for all 120-volt circuits in a house.

The intent of bonding CSST is protection from damage against indirect lightning strikes, not a direct hit. The idea is that if the earth on which a building sits has an elevated voltage from a nearby lightning strike, the voltage potential of the metal in the building will be elevated equally if all that metal is bonded together. That in turn lessens the chance of an arc between metals having differing potentials. The bonding requirement for CSST, with its mandate for a #6 conductor, is only found in plumbing and mechanical codes, such as NFPA 54, the UMC, UPC, etc., and not in the electrical code. The electrical code only looks at bonding of gas to complete a fault current path, and allows the size of the bonding to be as small as the equipment grounding conductor of the circuit that could energize the piping. As Marc said earlier, it is about protection from electrical energy that has the utility as its source, not a lightning strike. That said, there is a great deal of inconsistency within the electrical code on the required sizes and intent of bonding. In my own building department experience with high rise structures, I typically find bonding requirements that go well beyond the NEC minimums. The NEC is not about protection from a direct lightning strike. Lightning protection is an entirely separate matter. Facilities with lightning protection systems typically have passive NFPA 780 systems with air terminals, down conductors, and other components that are both elevated above and independent of the electrical systems and metallic components of a building. The bigger problem with CSST is poor installation practices. A part of the ANSI standard that governs CSST is that the worker be certified in the installation. For a few years, that kept CSST off the shelves of the big box home improvement stores and it was only available through plumbing supply houses where reps could stock it in return for holding training classes and providing certifications for installers. Sadly, that is not the case for many brands of CSST today, and it can be purchased by anyone. Lip service is paid to the ANSI standard by including a fill-in-the-blanks certification quiz that the purchaser is supposed to file. I anticipate that the greater threat to the future marketplace for CSST is not lawyers sifting through the ashes of a house hit by lightning, but insurance companies who will tire of lawsuits for shoddy installations.

The code-prescribed sequence of inspections here during new construction is that gas pipe is inspected visually prior to concealment, and pressure tested after concealment. If the plumber wants a pressure test at both inspections, that's fine, but only the one after concealment is required. The reason it can't be done prior to that is that you want to wait until all the nail guns have been put away before finding out if that pipe has a leak. This applies to black pipe, galvy, and CSST. Douglas Hansen www.codecheck.com

I think Jim is referring to the common range hood / microwave combination that is allowed to be cord & plug connected if on an individual circuit per 422.16(B)(4). In high-end kitchens we don't see these as often as the independent hard-wired range hood. Marc has convinced me with the comment about how some of these indoor units include resistance heat. We have concluded that the best way to achieve consistency within our department is to always require a local disconnect. This will comply with our mechanical code as well as the broadest interpretation of 440.14. Thanks all

Thanks I am researching this to come up with a consistent policy for our jurisdiction. Jim - I've asked this question in quite a few places, and so far you are the only person who seems to have found these on a frequent basis. I have never seen a disconnect for an indoor unit. The thing that California calls a mechanical code requires an electrical disconnect "adjacent to" any appliance regulated by that code and operating at more than 50 volts, yet it doesn't take much imagination to think of a few instances where that is never enforced (range hoods for one). The electrical code gives a pass to appliances that don't take more than 300 watts, which would include these indoor units. In the NEC, the branch circuit breaker is all that it needs. Some of them seem to derive their power from the outdoor unit and to operate at 240 volts, and some are wired independently. I'm hoping to sit down with some manufacturer's reps to find out more. I've read a couple of installation manuals, and they read like poor google translations into English. The one for Fujitsu shows an illustration without a disconnect and another with a disconnect, and has very ambiguous instructions. Until we have a more definitive answer, we are going to be asking installers to provide us with the installation instructions and attempt to follow what we think those are saying... Thanks

I am trying to determine the standard practice for installing mini-split systems. Does the indoor unit require a separate electrical disconnect within sight of the unit? Assuming the indoor unit derives its power from the outdoor unit, is the disconnect for the outdoor unit sufficient for both? If you don't see a disconnect, do you call that out as a correction item? Thank you

I think the attached photo came from Joe Tedesco and that it was staged. Click to Enlarge 16.23 KB

It's Hobbes!

Whether it is a garage or a carport would depend on what name they threw on it when the plans were originally approved, and as Jim says, would be irrelevant. It would only prove that paper will hold still while you write anything on it. In the coastal areas near here, panels have a fairly short life expectancy just from the moisture in the air. It doesn't seem to make much difference if they are Type 1 in a wood enclosure on the building exterior, or Type 3 with direct exposure. Those distinctions are about whether they are suitable for direct exposure to rain. The purpose of the original inspection seems to have come down to yes/no kinds of questions. If the rust on the exterior is being replicated inside the breakers, we have a problem. FWIW, in my day job (as an electrical plans examiner) if I saw this come through with Type 1 panels I would change it to Type 3. In the days when this thing was built, I would be surprised if the electrical wasn't simply a design build, with no specific panel types or locations shown on the plans.

As a four-plex, it would not be within the scope of the IRC. Many multi-unit buildings have open carports that are enclosed on three sides. Regardless, it shouldn't come to a question of how today's codes categorize such a thing. If in your opinion, the panels aren't suitable for that environment, I would say so. If I were in your shoes, my opinion wouldn't be based on code but on performance and the likelihood of future problems. I guess that gets back to the comments at the beginning of this thread. Douglas Hansen www.codecheck.com

These panels should have markings indicating whether they are NEMA Type 1 or NEMA Type 3. If they are Type 1, that would mean their listing is only for installation indoors. A carport isn't considered indoors; a garage is. Any indication that garage doors may have once been present? Douglas Hansen www.codecheck.com

I've never personally seen a two-phase system, though the diagrams I've seen for them are typically 5-wire, with a neutral and 4 phase conductors at 90 degree vectors. I have heard of these systems being used in railroads in Pennsylvania, though again haven't seen it myself. I think the issue in the inspection in question would be to alert the client that the system might not provide the type of power needed for standard induction motors and other equipment. While this could all be a head-scratcher, in the big picture it is probably not that relevant to your client. If the space is to be used as a warehouse/office, odds are their only needs will be for single-phase power. If they are going to install new machinery, they will be replacing the electrical power distribution system anyway.

warning - thread drift... When DC solar panels are installed in series and one panel is shaded, the entire string acts as though it were shaded. In other words, 50% shade on one panel in a string of ten reduces output close to 50% for the whole string. I'll wait for Marc to fill in the math... Douglas Hansen

Jack- the draft of the 2017 NEC eliminates item d from the list (probably a good thing since no such listed combination of breaker and OBC AFCI seems to exist). Here is their statement justifying the deletion of d: The Panel has deleted 210.12(4)(d) which required listing of both the OBC ACI and the Branch Circuit Overcurrent Device as a "System Combination." The previously cited UL research report titled "Effectiveness of Circuit Breakers in Mitigating Parallel Arcing Faults in the Home Run" provided significant statistical assurance that the "home run" portion of the branch circuit is protected from parallel arcing faults. UL issued another research report titled "Influence of Damage and Degradation on Breakdown Voltage of NM Cables" that had the following conclusion from pages 58 - 59: "In summary, the work described here shows that damage and degradation of a residential NM cable can lead to an arcing event, through voltage surges that break down the cable insulation and ignite arcing. However, the test results also indicate that the breakdown event is unlikely to initiate arcing that is sustained long enough to ignite the cable insulation or surrounding materials. In this study, arcing for hammer-damaged cable exhibited arcing during less than 10% of the surge events, and exhibited arcing that lasted over a single half-cycle. The arcing observed in this study is much shorter than what is required for an AFCI reacting to the event (eight half-cycles within 0.5 seconds, per UL 1699); however, the energy released in that short event is not expected to ignite the cable insulation." So whatever that means, it sounds like one part of this gets easier in the 2017 code.