electrical phase

Stehno,

Sounds like a non-union electrician to me :^)

Albert,

Are you reading all three phases 120v to ground?

I'd like to point out one error in Albert’s post. It has two do with two 120volt phases one row on the left side one row on the right.

A panel is configured so that a (full size) breaker and the breaker directly underneath it are on opposite phases. That way a two-pole breaker can be plugged into two spaces right next to each other (or one on top of the other) producing 240volts.

To truly isolate one half of a residential panel 120/240 volt. You would have to configure your breakers top to bottom skipping every other space.

I hope that makes sense. In all practicality there is no possible way to isolate any one phase for audio unless you have a three-phase panel with no 3-phase loads present in that panel.

My best advise is to always pull a dedicated neutral (white wire) with every hot. In addition add an isolated ground and I.G. receptacles

While I'm on the subject I'd like to mention that there is no such thing as two phase power. 120/240 is derived from a single transformer and is refered to as single phase power in the electrical trade in general.

3 phase power can only be 120/208, 277/480, or 120/240 with a high leg(Not very common except where lots of motors are present) These are standard 3 phase voltages used in the USA

Albert,
Your 3-phase power is probably 120/208. My guess is your reading 120v phase to ground, but if you put a good meter phase to phase it probably reads in the neighborhood of 208v. Check it with a high-grade meter (Fluke) sometime. This is a typical 3-phase voltage used in the USA no matter where you live.

If your reading 240v phase to phase then you probably have 120/240 with a high leg. That means one of your legs will be reading 277v phase to ground. I doubt you have this kind of power in a residential neighborhood.

In a typical residental service the panel does derive power from two separate 120v supply lines, but the supplying transformer is a single-phase transformer capable of producing 240volts. (This does not apply to you)

It does not take two transformers to produce 120/240

And without two or three transformers you cannot get two phase (No such thing) or three-phase power.

If Memory serves the transformer on the pole has a center tap (Neutral/ground), which allows for a reference point on either leg. Thus there are not two phases present just two hot's and one Neutral (Ground reference) derived from one transformer (One phase of a three phase system) on the pole

Hot to hot reading 240v
Hot to neutral reading 120v (when grounded to earth)
(Again this does not apply to you)

Your house has one main drop three phase derived from three single phase transformers on a pole or in an underground vault near by. These three transformers are configured to produce the desired voltage you seek which is typically 120/208 based on what you've told me already. This is in fact your main power at your main panel. 120/208 three phase.

From that three phase panel two hots and a neutral are sent to a single-phase panel (in the same closet). Even though we typically refer to this panel as single phase (Standard terminology) you are in fact feeding it with two phases. (ONLY BECAUSE YOU HAD 3 PHASES TO START WITH) This is a little different than a normal residential installation and in fact would be treated as a commercial installation.

Let's talk about the reason the two panels inside your house have different voltages. They are 120/240 panels which means you are using *A phase* and *B phase* tapped from your main three phase panel to feed one. *B phase* and *C phase* tapped from your main 3 phase panel to feed the other. You see that each panel has at least one different phase than the other. That's why the voltage reading is never the same at both panels.

It would be a little hard for me to believe that you’re only reading 120 phase to phase at these panels. You should be reading 208 phase to phase. There is no way an electrical contractor would do this type of installation unless he doubled the size of the supply neutral, you would also have to run a dedicated neutral with every hot comming out of the panel.

As for your meter That's called a CT meter (Current transformer) when you pull the meter you do not disconnect the line power, just the ct's. Pretty common in Commercial installations.

Albert,

There's no way to separate a 2-pole 220v breaker to one side or the other. I think we all know that? No matter what you do the noise from your 220 circuits will always be present on either side of the panel.

You could in theory separate all your 110v breakers to one leg of the panel, but that's not necessarily a great idea.

The main objective when terminating a panel is "load balancing" That is to say an equal amount of amps on each side. This will reduce the load on the neutral conductor. When you have 50amps on one leg and 50 amps on the other there is zero amps on the neutral.

However if you had 100 amps on one leg and 10 amps on the other you would have 90 amps on the neutral (Grounded conductor) This poses some serious concerns. Electricians and engineers always seek to reduce the load on the neutral by distributing the load equally to both sides of a panel. The same holds true in three-phase power distribution.

You may also want to consider labeling your outlets with a P-touch labeler. You could mark the phase (A, B or C) plus the circuit number and panel designation. That may come in handy when moving things around.

Take care

Balancing the panel= Best installation

Al, I give up :^)

See you on the next thread

You guy's need to stay out of your panels before you burn your houses down. You have no idea. Trust me!