Originally Posted By: Charles Palmieri This post was automatically imported from our archived forum.
Kevin it would help if you could be a bit more discript regarding the circuit configuration.
That being said there are several types of three phase services but typically your concern seems on target. Most services for other than industrial applications (SOMETIMES) will consist of A four wire installation. That is, phase A, B, and C (UNGROUNDED OR HOT) with a fourth grounded conductor that has equal potential from it to the other three ungrounded conductors (refered to as the neutral) this fourth (neutral ) conductor provides common lighting voltages generally 120V or 277V depending upon the premisis requirements.
This does not exclude three wire installations with out a lighting voltage, or neutral conductor. There are times where a straight three phase (so to say) is brought to the premises without a neutral. This is common as a three phase delta supply and in many cases one corner will be grounded (yes it is a grounded phase leg).
Primary feed
If you are looking at a HIGH (above 600V) voltage entrance in the diagrams you may be viewing an installation that does not have a utility supplied grounded conductor and in that case only three wires would enter the premisis. In these cases you ususally have a customer owned distribution transformer and the end user will benifit (usually) by having primary metering. What is the voltage of the conductors that you are questioning
Originally Posted By: dbozek This post was automatically imported from our archived forum.
Kevin,
The 3 phase wiring you see depends on the voltage being utilized. For instance a 3 phase 208 volt system would be 4 wire, or in other words, 3 hots (phase A, phase B and phase C) and a neutral. On a 240 volt 3 phase system there typically would not be a neutral conductor...therefore a 3 wire system. 480 volts is a 4 wire system as well.
At times they may bring in 480 volts and then feed another disconnect and a transformer to make 120/208 volts. In this scenario the 480 volts may run equipment and lighting and the 120/208 volts would then be applied to run general office circuits, etc. Hope I didn't confuse you with this info.
A question for the HI's.....can there be 3 phase going into a single family home?
-- You cannot help men permanently by doing for them what they should and could do for themselves. Abraham Lincoln
Originally Posted By: Greg Fretwell This post was automatically imported from our archived forum.
dbozek wrote:
Kevin,
The 3 phase wiring you see depends on the voltage being utilized. For instance a 3 phase 208 volt system would be 4 wire, or in other words, 3 hots (phase A, phase B and phase C) and a neutral. On a 240 volt 3 phase system there typically would not be a neutral conductor...therefore a 3 wire system.
...
...A question for the HI's.....can there be 3 phase going into a single family home?
If you do see 3 phase in a residential area it is as likely as not to be a center tapped delta with only 2 transformers. You also see that a lot in mixed use light industrial bay areas.
It is also called "red leg" or "wild leg" delta because the 3d leg is 208 to ground. The other 2 are 120 so you can feed single phase loads normally.
The advantage for the utility is they only need one extra transformer to give you 3 phase. The center tapped transformer is the standard pole pig you have for single phase. The other transformer may actually be smaller since they expect single phase loads.
Originally Posted By: gbeaumont This post was automatically imported from our archived forum.
Hi Dennis,
About the only time I see 3 phase up here is on older former Agricultural buildings, and very occasionally, supplying some part commercial buildings, if I know I am inspecting a building with 3 phase I take a reformed commercial electrician along with me. ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)
Originally Posted By: dbozek This post was automatically imported from our archived forum.
For the most part, same here. Only a select few older homes. First time I saw it I was a little puzzled as to why. Recently, I did a small job for one of the churches here and yep…they had it. It was kinda funny cuz they were going to throw this festival of sorts and they needed to bring out some power to run booths, etc and the deacon was worried he didn’t have enough electrical to do that. I told him he had enough to run the city
– You cannot help men permanently by doing for them what they should and could do for themselves. Abraham Lincoln