Panel setup

[Woodzykiler]

lets keep this simple.
If a USA Home has 200 amp service, is it 100 amps per phase or 200 amps per phase. dont worry about the voltage.
Before you rudely close this again on me, Im not from the USA, I moved here a few months age and still doing my journeyman training.

 

[LarryFine]

Welcome to the forum. I don't know what happened to you before.

A 200 amp supply is 200 amps per line, whether it's one, two, or three lines.

Single phase and three phase are wave-forms, not line conductors.

Added: Try to take being corrected as teaching, not criticism.

 

[Carultch]

lets keep this simple.
If a USA Home has 200 amp service, is it 100 amps per phase or 200 amps per phase. dont worry about the voltage.
Before you rudely close this again on me, Im not from the USA, I moved here a few months age and still doing my journeyman training.

It's 200A on line 1, and 200A on line 2. While not technically called two phase like one might think it should be called, for ideal waveforms, it is mathematically identical to two 120 Volt waveforms that were 180 degrees apart in phase. The accurate term for this is split-phase.

The current is not additive, since the two line currents follow source voltages that are opposite to each other at any given snapshot in time. Current is subtractive on the neutral. When balanced, there is no neutral current, and equal and opposite current travels on both line conductors, that are 240V to each other.

 

[roger]

Watts are Watts

 

[jim dungar]

Is there someplace in the world that teaches electricians to add the current per phase arriving at a single total value? At what point does an apprentice usually start learning basic electrical theory?

 

[garbo]

It's 200A on line 1, and 200A on line 2. While not technically called two phase like one might think it should be called, for ideal waveforms, it is mathematically identical to two 120 Volt waveforms that were 180 degrees apart in phase. The accurate term for this is split-phase.

The current is not additive, since the two line currents follow source voltages that are opposite to each other at any given snapshot in time. Current is subtractive on the neutral. When balanced, there is no neutral current, and equal and opposite current travels on both line conductors, that are 240V to each other.

We were taught that the standard 120/240 volt 3 wire residential services are not split phase but called a 3 wire Edison system with the grounded conductor ( neutral ) just a center tap . Only split phase we were taught in over 500 hours of class were done single phase motors that most used a capacitor in series with the start winding to produce an out of phase with the run winding. Have worked on two & three phase systems and never called them split phase like some people call them.

 

[ggunn]

lets keep this simple.
If a USA Home has 200 amp service, is it 100 amps per phase or 200 amps per phase. dont worry about the voltage.
Before you rudely close this again on me, Im not from the USA, I moved here a few months age and still doing my journeyman training.

200A per phase. Phase current equals line current in a balanced system whether it is split phase or three phase. If it is unbalanced the difference is carried by the neutral.

 

[LarryFine]

Since we're bringing it up again . . .

While not technically called two phase like one might think it should be called, for ideal waveforms, it is mathematically identical to two 120 Volt waveforms that were 180 degrees apart in phase.

In my opinion, it's easier to understand and perhaps more accurate to describe it as two 120v waveforms that are in phase and wired in series. This is best illustrated by a dual-secondary transformer wired for the higher output voltage.

 

[TwoBlocked]

... At what point does an apprentice usually start learning basic electrical theory?

Some apprentices never do, and some Journeymen never really did.

 

[letgomywago]

Some apprentices never do, and some Journeymen never really did.

Some should be changed to "to many" and of those that do many never understand the true function of the theory in practice. I've seen journeymen not know that you can pick up induction on a dead line and trick a digital meter they think that it says 104v but when you try to turn on the light it doesn't work and the voltage goes away that something else is wrong.

 

[TwoBlocked]

Had a "helper" the other day ask why you could see the moon during the day. At the same site we were ringing out some level switches. Two "techs" called me down from a basket lift because all the cables showed continuity. We had a little lesson about the problem with auto scale and why you don't pinch both wires to the leads with your fingers. One set actually read 1.5 ohms and the others 0.8 megaohms.

But hey, if you don't know, you don't know. And if us experienced guys refrain from belittling, they will continue to ask dumb question when doing dumb things and become better at what they do. (We will more quickly find out what they do and don't know in the bargain.)

 

[LarryFine]

Some apprentices never do, and some Journeymen never really did.

Agreed. Because of my interest in electronics since I was a kid, I knew more about electrical theory than the guys I worked under as a helper.

 

[ggunn]

I once had an inspector (a master electrician) who would not be convinced that a load in a PV AC combiner will not add to the current in the conductors going back to the point of interconnection while the system is running. When I tried to tell him in the most non condescending way possible that current cannot run simultaneously both directions in a conductor, he just got mad and walked away.

 

[infinity]

Is there someplace in the world that teaches electricians to add the current per phase arriving at a single total value?

If all of the loads are 120 volts why can't you add the values? A 200 amp, 120/240 volt service can supply 200+200 or 400 amps at 120 volts.

 

[Carultch]

If all of the loads are 120 volts why can't you add the values? A 200 amp, 120/240 volt service can supply 200+200 or 400 amps at 120 volts.

Because the peaks of the current waveforms, are not concurrent. Adding up the currents from both lines, doesn't tell you anything of significance.

 

[electrofelon]

Because the peaks of the current waveforms, are not concurrent. Adding up the currents from both lines, doesn't tell you anything of significance.

There are some times when "amps of 120" is relevant, generators being a common example. Another example is where I have a small feeder (often a small branch circuit being turned into a feeder) that will be serving only like to neutral loads. In a lot of these cases I am not doing a formal NEC load calc, just doing a quick evaluation of what I have and what I need to power.

 

[jim dungar]

If all of the loads are 120 volts why can't you add the values? A 200 amp, 120/240 volt service can supply 200+200 or 400 amps at 120 volts.

No. It can supply (2) 120V circuits at 200A each. It cannot supply (1) 400A circuit unless the two sources are paralleled, which cannot happen per NEC requirements when the source is a typical center tapped transformer.

 

[infinity]

No. It can supply (2) 120V circuits at 200A each.

That is 400 amps of 120 volt loads.

 

[jim dungar]

That is 400 amps of 120 volt loads.

No it is not. If you have (2) 1/2 ton trucks, you do not say you have '1 ton' of capacity.

 

[infinity]

No it is not. If you have (2) 1/2 ton trucks, you do not say you have '1 ton' of capacity.

Let make it simple I have 20-20 amp, 120 volt heaters (400 amps total) can I hook them up to a 200 amp, 120/240 volt panel?