A Question About 3-Phase Delta

I am trying to follow this last bit of traffic.

You are saying the A and B are probably both the same phase or at least, in phase?

aDIYguy-

Yes, they are the same phase and in phase with each other. The difference is that one is on one side of the neutral (A--Neutral) and the other is on the other side of neutral (Neutral--B). A--Neutral = 120 volts, Neutral--B = 120 volts, A--B = 240 volts.

Your system is one phase. Without going into unnecessary, only confusing, descriptions the word "phase" refers to where on the utilities generator the power is being taken from in relation to the other wires. Imagine a clock face. with a single phase system there are two wires, each one connected to the generator, and connected at 12 o'clock and 6 o'clock. Since the left side of the clock always matches the right side in relationship to each other, it is called "single phase".

On a 3-phase system, using the clock example, there are 3 wires connected from the generator to the clock. These wires are located at 12 o'clock for wire A, 4 o'clock for wire B, and 8 o'clock for wire C. Since the voltages across any two wires are never the same A--B, B--C, and C--A; but the voltage difference between each pair of wires vs. another pair continues to be the same this is called a 3-phase system. Back to the clock- the top right third 12--4 is one phase, 4--8 is one phase, and 8--12 is the last of 3-phases.

If this analogy is confusing or hard to understand I suggest you refer to Wikipedia at:

http://en.wikipedia.org/wiki/Three-phase_electric_power This can supplement or replace the above.

Good Luck, Old Salt

Thanks OldSalt, that was the right level of detail for me to digest any better explanation would have given me a head ache. I cracked a book on 3 phased electricity over 35 years ago. I still remember some of the basics but I can't recall everything I did yesterday let alone that I read over 35 years ago. I remembered just enough to be 'dangerous'. I put dangerous in quotes because I am not going to act on something I don't know cold.

aDIYguy-

Excellent decision!

I sometimes bring myself back to reality, and no offense intended to anyone mentioned, that most dentists, surgeons, jewelers, doctors, etc. are just mechanics or engineers like you or me. They just work on different things than I do. I work on a valve, the heart surgeon works on a heart valve. Only difference is he goes through a lot more training than I do and his is more life critical most of the time. Same for dentists and welders. They both fill holes but the dentist does it with a much lower temperature. They both work with their hands filling holes. So on and so forth.

As you reminded yourself, it's just as important to know what to not do as it is to know what to do.

Good Luck, Old Salt

OldSalt - I am not easily insulted. I do not mind being called an ignoramus if I don't know something.

Our core beliefs are similar. As Dirty Harry stated 'a man needs to know his limitations'.

We grew up when it was OK to take risks. If I remember correctly, you also reflected you started work before OSHA. That does make you an old salt.

The reality is I have worked on live 110 off and on since before some of the respondents were born. I have never experienced a full body 110 shock. Both my teachers, my father a corporate/plant engineer and an electrical engineer I helped with home projects for the 4 years I was in HS could't make the same claim. Education isn't everything. I have a bit more respect for it than they did plus I am ultra-methodical. Just because the 'breaker was off' didn't prevent me from testing the wires for power. Working in heavy industry taught me not to assume anything that might kill you.

I am still weeks away from the wiring project.

PS Did you know you can smoke in an area heavy with diethyl ether fumes? Just do not light another one. I learned that tidbit from a world-class chemist who is long dead.

aDIYguy-

My statement was addressed to others who might take offense with my analogy between what some consider to be highly skilled and "eloquent" professions. I learned that while working as a younger member of a Dental alloy company. Their sales and marketing theme was "Dentist are just mechanics" and this sometimes extended to "and the mechanic on the corner is probably better worth more to you than the dentist".

I too am an avid believer in the philosophical observations of Dirty Harry, My favorite, and one that prevents my temper from raising to higher levels and keeps the blood pressure down is "Opinions are like a$s holes, everyone has one".

I too have touched some hot circuits. Almost all of them were planned and I didn't touch any exposed wires or terminals as I had planned. Those few that I did had a very big influence on my thinking and future actions. As I learned more and did more they happened less frequently. Currently I hope my learning curve has flattened out at zero frequency. I must say though I have an implanted defibrillator for my ticker. It excited once do to its correction of a problem in me and I have never experienced such a complete body consuming shock. It effected all of me but I am thankful that I had it and it did what it was supposed to do. A downer with this unit is that I can no longer arc weld due to adverse effects on the defibrillator.

I am aware of the situation you mention about diethyl ether fumes. When a firefighter is confronted with a house full of natural gas he always shuts the gas line off at the curb and checks the valve with water for leaks before ventilating. In this situation the pilots could be still burning under certain conditions and if the UEL level has been exceeded the flame could still be burning with no explosion or fire. When they ventilate and the ambient level of gas goes down to the UEL the house is going to go BOOM! Turn the gas off at the curb and you shut down all sources of flame prior to ventilation so there is no source of ignition. Don't try this with Ethylene Oxide, it has a LEL of around 2% and a UEL of around 98%.

I don't consider you as an ignoramus or insulted easily. You are most likely like me, a continual learner and wiser one as we learn more. Age does have an advantage!

Good Luck, Old Salt

No, I didn't explain clearly.

Di-ethyl ether is worse for the lower limit than Ethylene Oxide. I just checked, Di-ethyl Ether flammability range is 2-48 vs ethylene oxide 3-100 both super dangerous. I thought Di-ethylether had a much higher limit but my memory isn't as relyable as it once was.

A smoldering fire without flames, like a lighted cigarette, will not even ignite Di-ethyl Ether. That was the point I was trying to get across.

Who are you asking?

What are "A" & "B"?

Andy Germany-

#1 poster #49 as noted in upper right corner "#50 in reply to #49". Therefore the question is directed to aDITguy and anyone else who reads answer #50 and needs further explanation.

#2 as noted in the verbiage 12 o'clock for wire A, 4 o'clock for wire B, and 8 o'clock for wire C.

Any other questions?

Good Luck, Old Salt

I thank you for the explanation, but in #49 there was no reference to who it was referred to. It cannot be an answer to #50 as #50 came later in time, aprox 3 hours time difference.

There was no reference to any other post....look again!! Which is exactly why I asked!!

Your explanation therefore does not "hold water" so to say....it was at least amusing, I thank you for that!

As was the second explanation, many thanks for that as well.....

But the phase to a clock face analogy was not mentioned in the Wiki page mentioned in #50, probably because it could be misleading for some.... I never found it needed and my tutors also did not explain it in such a manner either. Therefore to my mind, simply not needed...sorry.

I have seen that phases are often colour coded, to assist installers in getting the rotation correct. We used the same system on RN ships. We used R-Y-B as in Red, Yellow and Blue.

It does not really matter what the colours are as long as the rotation requirements can be properly handled.

Referring to:-

http://en.wikipedia.org/wiki/Three-phase_electric_power

Andy Germany-

I expressed my answer to your question based on my understanding that "In Reply To" was of the same nature as "reference to". If my understanding of the English language is incorrect, I apologize. Unfortunately as this time of my life it's too late to change. This has been sufficient so far so I'll stick with it.

Yes, #49 has no "In Reply To". I didn't write #49 so I don't why the author did that. My post #50 referred to the previous post, of unknown reference, #49. Yes, my reply #50 was posted at 12:46 pm in reply to #49 posted at 9:56 am of the same date. Exactly 2 hours, 50 minutes apart. It seems appropriate that the answer would follow the previous post. #50, my reply, was based on these premises. He asked, #49, and I answered, with #50, a later posting. Likewise the question had no reference to a prior posting but the answer refereed to that question "#50 In Reply to #49" as stated previously. If this does not "hold water" perhaps I should, but won't, stoke the fire to a higher temperature. Any time you would like a good joke as you expressed in your posting, may I suggest perhaps either "Saturday Night Live" or the "Rejection Hot Line" in Philadelphia, PA, USA They are extremely humorous. I can't give the hot line's phone number here but if you use the private mail function I will forward it to you. They are both quite humorous.

Yes, the phase to clock face analogy was not mentioned in the Wiki page. This was done so that if the reader did not understand or was confused with my simplification of the question, he had an alternate source to refer to that might have another approach to his question. Sometimes a different approach brings an answer easier to comprehend. An analogy for this might be "to go to the right you can either make a right-hand turn or three left-hand turns." Yes, this is a longer trip but much easier if there is a road block in the way of the single right turn. If the Wiki reference was misleading this is the first time I have heard of that. These analogies and the clock analogy seem appropriate to help the questioner in his pursuit of additional information. He later stated--

Thanks OldSalt, that was the right level of detail for me to digest any better explanation would have given me a head ache.

I am glad to see you never needed the Wiki reference, I didn't either.

The use of the A, B, and C and the reference to the face of the clock were used because I, like many others, didn't know exactly what the complete level of knowledge was on the subject for the questioner. Often times it is better to start at a lower level if this is not know. Yes, R-B-Y-Bu-Or-G-Br-V-Pu and many other color designations can be used. I, like you I presume, learned that way. Since I didn't know the appropriate level to use I went back to a more easily and less color vs. wire use method, the clock face. I saw this used in a sophomore EMF class and most of the students who didn't understand the wire color system readily learned with the clock face concept. That's worked for me training bewildered students so I'll stick with it.

Agreed, "It does not really matter what the colors really are as long as the rotation requirements can be properly handled". Some students have an initial confusion with the R-Y-B vs. B-Y-R explanation so this was presented in a simpler manner. That was the clock face and A, B, C method. That's worked for me training students so I'll stick with it.

Thank you for your questions. As before, If you have any others please do ask.

Good Luck, Old Salt

An update -

I talked with an electrician a week or 2 ago. I wanted him to suggest a local electrician to check my work. Although he never saw my work, he has known me socially for over 20 years. My wife is best friends with his sister. We had about a 5-minute Q&A session. He told me I could skip paying electrician to check my work as I have done in the past. He concluded that I actually did know what I was doing for this limited job but suggested I use PVC instead of the aluminum conduit that I planned to use.

One other note: Spas are not like pools where a great deal of water splashes out of the pool. With my years of experience, using the old spa 99% of the water loss is due to the drip from persons leaving the spa. Kids are under tight supervision. There are no water fights or cannon balls. The area where the conduit will be is actually less wet than the outdoors because it is very sheltered. The PVC connections ought to be easier to keep watertight than the aluminum connections. I have never seen a PVC joint leak even under pressure.