Exactly! I love this forum, it has been wonderful! I try to be involved a much as I can, to help others as much as I have been.
We all have our different strengths and experience, so this community is great to share that with.
You are assuming that home inspectors know the differences between the different connection arrangements. Also, you have been known to post incomplete information (as in this case) or use improper terminology (such as referring to single phase systems as having two phases).
My goal is to provide clear, complete, and accurate information to home inspectors. I don’t assume that when someone posts incomplete or inaccurate information that home inspectors will be able to understand.
You said a “Delta system would have a high leg”. That could be interpreted by someone unfamiliar with three-phase systems that ALL Delta connections have a high leg. Of course, they do not. Had you said “A center-tapped Delta system would have a high leg”, that would be an entirely different matter. If an inspector were to encounter a corner-grounded Delta system and had taken your comment at face value, they would not doubt be confused when measuring Voltages.
Jeffrey,
The two basic configurations for three-phase systems are Delta and Wye (aka Y or Star). There are variations on the two basic configurations. Like with most things, there are advantages and disadvantages to each. There are many things that are factors in deciding which is the best option for a given installation.
Delta connections are called Delta because the coils are schematically drawn as a triangle and the math involved is based on the geometry of a triangle (and, of course, a circle). Wye connections (aka Y or Star) have a center connection at the center point of the three phases. Schematically, they are drawn to look like the capital letter Y.
Delta connection arrangements can have a center-tap off one of the three secondary coils. A center-tapped Delta has once leg that has a higher Voltage then the other legs. That is the High Leg. The High Leg is identified by the color Brown, Yellow, or Orange. In my classes where I have electricians from all over North America, I’ve learned that the color used to identify the High Leg is often a matter of local custom. In my personal experience in the field, Orange and Brown is used most often. I’ve never used Yellow to identify a high leg but electricians have told me that Yellow is common where they work.
A corner Grounded Delta has one leg that is 0V to ground. The purpose of the ground is the same as in any electrical system. That is, it is there to help stabilize the system. It is grounded but it is NOT a neutral conductor. There is NO High Leg in a corner grounded system.
Based on comments elsewhere in this conversation, particularly the comment about measuring Voltages, an inspector who had taken Robert’s comments at face value about there being a high leg would undoubtedly be confused when they don’t find a high leg and they measure the Voltage to ground and find one with no potential (aka Voltage) to ground because it is corner grounded, not center-tapped.
A home inspector who is not doing many, or perhaps any, commercial inspections could conceivably go through their entire career without ever seeing a three-phase system, especially in a residence. I certainly don’t assume that a home inspector has any knowledge of three-phase systems because it is something that we home inspectors don’t often see. I do hope to shed enough light on the subject that they are not completely confused or overwhelmed when encountering a three-phase Delta system.
Three-phase four-wire Wye systems are much more common in general and specifically in retail establishments, office buildings and light to medium manufacturing. Compared to Wye connected systems, Delta systems are relatively rare. I should note, however, that I have found that there are regional customs. There might be places where Delta system are more common than other places.
I don’t know Robert personally so I don’t know what his knowledge level is. I do know from having read many of his posts that you have to be careful when taking anything anything he posts at face value. On one occasion he referred to single phase systems as having two phases and later said something to the effect that he assumed inspectors would know what he meant. I can tell you from my experience teaching electrical to home inspectors that most do not know. Someone with little or know electrical background would not know that he said one thing but meant another.
It is frustrating and discouraging to me when I have inspectors in my classes tell me that they are confused because they read stuff on the InterNACHI message board that is factually incorrect. I spend an inordinate amount of time with the whole single-phase/two-phase thing. Add to that other stuff like so-called electricians not knowing what a Multi-wire Branch Circuit is, not understanding grounding, and other concepts, and so on but posting misinformation and it is all a real mess.
Robert apparently thinks it wrong of me to help clarify that it is CENTER-TAPPED Delta connection arrangements that have a high-leg, NOT ALL Delta connection arrangements. It is exactly because of this kind of stuff that I rarely contribute in this forum and will usually only give detailed answers to certain people (with you obviously being one of them). Everyone else can merrily go about their business assuming that all Delta systems have a high-leg.
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George, as usual you’re consistent with your inability to actually read what’s posted. If someone doesn’t understand something they can always ask for more information. You seem to think that you’re the smartest guy on this forum well you’re not, not even close. Here’s an example: these are items that were posted before you came alone and mentioned a corner grounded system which has nothing to do with this thread.
I could ask a 3rd year apprentice to identify a 3Ø system with a 42 circuit panel with 18 single pole CB’s and not one of the single pole CB’s on the B phase and they could figure that it’s not a corner grounded system. You call yourself a forensic consultant I feel sorry for your clients.
I’ll assume that your condescension and your insults make you feel good about yourself. As before you’re back on my ignore list.
This is a Home Inspector forum, not a forum for third year apprentice electricians. Why don’t you ask the Home Inspectors how many of them knew that you were referring to a center-tapped Delta?
You have demonstrated in multiple posts that you don’t know that residential systems are single phase (you thought they are two-phase), don’t know what a Multi-wire Branch Circuit is (you thought two ungrounded conductors on the same leg sharing a neutral is a Multi-wire Branch Circuit), you thought (or implied) that all Delta systems have a high leg. I could go on.
You aren’t even an InterNACHI member. You come on here with incomplete or inaccurate information. The sad thing is that some of the inspectors here don’t know enough to know how often you post wrong or misleading information.
Exactly right… when I started inspecting 21 years ago I was TERRIFIED! It took the BO 2.5 years to talk me into becoming a inspector. I was a sub contractor/framer for 6+ yrs, picked up trim work then had a sheetrock company finally I became a custom home builder and was hands on. Plenty of high end remodels to fill. Did that for 12 years prior to becoming a inspector. Plumbing, HVAC and electrical was NOT my strong point. I had to learn a lot of this on the fly. I got my ICC certifications no problem but I promise you, certified does not mean qualified. It took me several years and with these smart phones, a lot of help from sub contractors I managed to muddle my way through. I’ve never been one who put pen to paper without understanding the “whys”. The “book says so” is not an acceptable answer when you could very well be making someone’s life difficult for no good reason. I have only been on InterNACHI for 2.5 months? I watch these forums constantly for gems just like the one you posted. Best of luck Daniel 
Actually, I will ask it anyways…Robert, looking at photos again, is this circuit an issue? Besides the double tap, it appears that a 240 circuit has been made on this breaker. When that happens, does it matter which phases the connections are made on? With a single phase panel, each bus carries 120 V, but is that the same with 3 phase? I did not follow these conductors to see if they were the same circuit, but I would assume they were… (black and white)
thx again!
never mind robert, I had a dumb question, but figured it out… 
Any 240V load can share the the high leg & another phase, BUT you cannot use a standard 120/240V slash rated breaker, because the voltage (208V) of the high leg exceeds the lower voltage rating of a 120/240V rated breaker, so a 2-pole breaker rated for 240V must be used, there are 2-pole breakers that look that they are using the high leg, most of those panels are ITE, (now Siemens) with other makes of breakers installed, they need paperwork stating that they are UL classified to be used in ITE panels, the only one that I am aware of is made by Eaton & it’s not a BR frame breaker either.
240 volt rated 2-pole breakers are rare & expensive but are catalog items.
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I hardly think that someone with Robert Ms qualifications would say a residential panel was two phases given his well documented knowledge on this and other professional forums. He has helped many here increase their knowledge and understanding of a complex part of home inspections.
Thanks Jim. I chalk it to somebody whom for whatever reason has made it personal because they have an axe to grind, so they misread and misquote things that are stated, often by taking them out of context and then resorting to personal attacks. Regarding your post (two phases: another misquote) I’ve been working on various 3 phase systems for more than 35 years so I know how they work.
The other point that I want to make is that even if someone posts something that isn’t full explained or is unclear everyone is free is ask for a clarification or for more info. There are times when things are written quickly or don’t translate exactly into the typed words the way that they are conceived in your head. And regarding that other guy, he’s on my ignore list.
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One thing to note, the high leg is not necessarily going to be on the “B” phase, it was quite common before code required it to be on the B leg for it to be landed on the C leg, and some seem to continue it because utilities require it to be on the C leg in the meter can. Another form of residential 3Ø is with a Delta Breaker (now prohibited by the NEC) which is used in a single phase panel, see photos in the following link.
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