Huh? Just because there is 3 phase at the street doesn't automatically mean a (single family) residential customer will get anything other than split phase 120/240.
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208 volt 20 amp
- Thread starter Woody5575
- Start date
@Woody5575 I am comment number 23, and we still haven't seen what outlet type this is. That should be able to wrap things up easily.
Just so we're clear about all this:
High tension AC transmission systems are almost always 3-phase, usually at some ridiculously high voltage.
Substations, in general, take the high voltage and downconvert it to something lower: 800 3-phase, 440 3-phase, something like that. You'll see this as the heavy wires up near the top of some, but not all, of the power poles on a street.
I Have Been Informed by, apparently, long-term practitioners of this kind of thing, that a Power Company will take two of these high voltage phases, connect them to a Honking Big Transformer and, out of that, generate the split-phase used by a group of houses. That's generally for residential.
However, commercial people often have high-voltage motors and such floating about and those generally Work Better if supplied with 3-phase power. (Easier to get the motors to run in the correct direction when starting, if nothing else.) So, in the back of a typical supermarket there might be 3-phase 440 coming in, 3-phase 120/208 coming out, and breaker panels with the A,B,C regime rather than the One-Phase/Two-Phase that residential people see.
However, having said that: No Rules Are Broken if, on some residential street or other, there's a 3-phase transformer with 480 VAC in, 3-phase 120/208 out, and pairs of the 120/208 are delivered to a bunch of individual houses. As pointed out in the comments, above, where some fellow in Queens stated that that was the case in his neighborhood.
The only reason we're banging back and forth on this topic is that the OP stated that he had an electrician give him, specifically, a 208 VAC socket, but also implied that his house was on 240 VAC.. and the 240 VAC would have been split phase, so what the heck is going on?
Im not surprised at 2 pages of talk on this, even though the OP hasnt posted a picture to help clear it up. If there is one thing a large portion of TMC membership likes to do, its help people figure out their charging situation.
This is something I have always been gratified by, and in fact was one of the reasons I said "yeah I will help out" when they asked me to help (volunteer) moderate.
Would be nice to see the outlet, though
. @Woody5575, throw us a bone here, lol.
<crackling campfire sounds>
"And while the thread lives on to this very day, @Woody5575 has never been heard from ever again..."
Understood, I simply meant that the presence of 3 phase distribution (with or without a neutral) does not automatically mean 120/208 low voltage service. I've done electrical work at several houses (mine/friends/family) that had 3 phase on the street that are definitely 120/240 service, so a single phase transformer with a grounded center tap on the secondary. I've never seen a single family home with 120/208 service, but it's certainly possible.
My local utility's tariff states "service supplied under this [residential] rate will be single phase, 60 cycle, alternating current, normally three wire service at a nominal voltage of 120/240 volts or three-wire 120/208 volts, whichever is available at the location."
Just a minor correction - voltage out of the substations and on the wires running down your street is typically ~10kV. Engineers for my local power company have told me they generally use 13.2 or 13.8kV. Lower voltages (like 120/240, 120Y208, 277Y440, etc) are generated by a stepdown transformer, either utility owned (pole/ground mounted), or customer owned, for the large industrial users that take distribution voltage directly.
Same tariff, large C&I users: "Service supplied under this rate will be 60 cycle, three-phase alternating current normally at a nominal voltage of 120/208, 277/480, 2400, 4160, 4800, 7200, 13,200 and 13,800 volts. All voltages are not available in every area."
I still want to see a picture of the OP's outlet. A voltmeter reading would be interesting as well.
Eric33432
Member
Exactly correct. Most distribution in the US these days is 4 wire wye, but some is still delta. I've noticed a lot of 3 wire delta in California. Most if not all distribution I have seen in Europe is also delta. So, there are two voltages, for example FP&L is mostly 13,200 phase to phase and 7620 phase to ground. In the US and Canada transformers for individual houses take in these kinds of voltages and put out 240/120 split phase or 208/120 or 480/277 4 wire wye. There are also some that are wired delta, or open delta, but I have not seen much of that.
Most larger buildings get 277/480. They use 277 for lighting, and 480 for large loads like air conditioning. Then they have dry type step down transformers for the 120/208 loads. Go into most Home Depot stores and you can see these transformers hanging from the ceiling near where all the electrical panels are located.
This article goes into the details for anyone who wants to nurd out on distribution transformers.
I'm not from Queens. I just noticed the 3 phase distribution every time I drove out to JFK airport back when I lived up there. As an EE I found it interesting.
Another disappearing OP?
Unless a house had two different services it has to be either 208 or 240 unless a transformer was installed. 208 is not impossible but very unlikely. I seriously doubt a transformer would have been installed as they are expensive. Almost all motors work fine on either voltage. Maybe all the OP said to his electrician, after seeing the 208 volt rating on the motor is: "Hey, I need a 208 outlet installed here for my table saw", and that has resulted in 30 posts by people trying to help him!
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