What's going on my friends this is Dustin Stelzer with Electrician U and
today we're going to talk about different VOLTAGE SYSTEMS
Alright so when I was an apprentice I always wondered, like, what is the whole
120-240-208-277v how do all of these numbers matter and where do we get them from
so starting out you're gonna come across like a lot of low voltages you're
gonna come across some medium voltages and then there's higher voltages
now as electricians we call them low medium and high or we say line voltage
but really high voltage is talking about like five hundred thousand volts and as
an electrician you're never gonna come across that stuff so just for what we
run into in the field typically we're talking about stuff under 1,000-volts
and usually above 50-volts unless you're talking about low voltage systems
you know we're talking like 5-volts
10-volts 15-volts 24-volts stuff like that
so let's start out with the really low voltage stuff you're gonna come across
probably 5-volts and 10-volts maybe 15-volts DC a lot of times in lighting
control systems or energy management systems if you're going to work in
places where there's like refrigeration and remote monitoring a lot of those
systems work off of communication signals back and forth where they're
sitting like a small little 5-volt DC pulse and that's how they're signaling
some of this stuff to turn on and turn off but it's pretty rare that you're
going to come across those voltages otherwise another one is 12-volts so
12-volts you're probably gonna come into all the time
there's LED ballasts, drivers, things they're actually called drivers not
ballasts but there's a lot of places we're going to come across 12-volt power
supplies so 12-volts is a fairly common low voltage voltage they're going to
come across and then you've got 16-volts 16-volts a lot of doorbell transformers
are run on 16-volts or 24-volts but that's the rest of these voltages as
well 24-volts is another really common thing that you're going to find in a lot
of LED like strip lighting because if you run these like LED tape you run
these strips over a really long distance 24-volts can actually just push a lot
further down the line without there being a voltage drop and you don't have
that dimming effect so you're gonna run into a lot of that in those kind of
environments 24-volts you're probably gonna run into a lot in equipment and
like you know large cabinets where you're running machinery a lot of times
will 240-volts or 120-volts in and then
convert it down to 24-volts and run all of these small little signaling things
so it's kind of like putting a panel into something that's only 24-volts it's
like something you can pull a lot of power and distribute it through a lot of
other little things but that's pretty much it for under 50-volts those are the
voltage systems that you're going to come across now a lot of them are AC or
DC or some of them are both but we'll get into the whole difference between
how AC voltages and DC voltages operate in a later video so next we're going to
talk about voltages between 100 and 250-volts this is kind of the next class of
voltages that you're going to come across and both in single-phase and
three-phase so in single-phase you're gonna come across systems that are 120
240 and that makes sense right you've got 240 volts and you cut it in half you
get 120 when you have a neutral present otherwise everything all the motors and
machinery would just run off 240 volts but the math makes sense how you get
from 120 to 240 right it's just cutting it in half you're cutting your voltage
in half less pressure but once you get it a three-phase it's kind of weird
because you have things like 208 and it's like okay well how does 208 factor
into it so if you have three-phase there's two different kinds of
three-phase services there's either a Wye configuration or a Delta
configuration and it's based off of what the power company supplies to a building
what's in the area sometimes in different factories and different
buildings you're gonna have motors that require a little bit more torque and so
they're gonna need a Delta service rather than a Wye or something that has
like a whole bunch of lighting loads specifically it's gonna do better on a
Wye configuration because you're gonna have a neutral with it as well so
there's reasons why and again I'm not gonna get into all that crazy stuff in
this video but I just want to break down how these voltages are derived and what
they mean so when you hear 240 and 208 kind of the same thing really 240 just
means that you're working with a Delta configuration the transformer that's
provided is in a Delta wiring configuration and that just means that
each one of the coils inside or each one of the windings inside that thing
are run end-to-end. In a Wye configuration the centers of
every single one of those coils meet up so because they're wired in that
configuration you just get a different voltage out of it when you run incoming
power, outgoing power is slightly different so just know that if
you're ever wiring a place and all of the specs call for 240-volt stuff and
you're reading name plates on equipment it's all 240, 240, 240 and you realize
that your service is 208 you need to say something you need to address that and
figure that out because that equipment is usually rated within 5 or 10% of its
value so if you overdrive or underdrive those motors you're going to burn them
up over time and something like a $200,000 CNC machine like this really
really important that know so that's pretty much it for the for the 250-volt
and and under-voltage systems now we get into a little bit higher voltage this is
a lot more dangerous stuff but you're talking 277 to 600-volts so 277 is very
similar to 120 you know in a lower voltage situation it's where there is a
hot in a neutral they're just a lot higher potential so 480-volts is the
same as 240-volts and 277 is the same as 120 so most systems that you're gonna
come across that are higher voltage you're gonna have 480/277v or you're
just gonna have 480 there is one other voltage class above that and
that's 347 and 600 volts so same thing 347 is just hot to neutral it's
just a really really super powerful amount of power and then the 600 is the
line-to-line we're hot too hot but that's pretty much it that's that's the
voltages I'm gonna go on the black border or the white board over here and
sit in kind of do some calculations so that you understand like how you're
deriving you know some services we'll have 240 and 208 and get 120 and like
understanding how all that works I'm gonna actually break that down for you
alright so let's look at different windings for different transformers and
sit and break down how these different voltages come out so first we're going
to look at a corner-grounded Delta and that's just a Delta configuration again
on Delta that means that each winding of this transformer (there's three windings)
each one is wired end-to-end or "in series" so with corner grounding that
means that they actually ground one corner or where two of these meet
together so the voltage in something like this if we're on a lower voltage
system is going to be 240-volts between each end of that winding and it's the
same for all of the windings so you're gonna have 240 between all of them and
from any point to ground you're also gonna have 240 so that's pretty easy
that makes sense right, there's no neutral in here at all,
nothing's tapped so that you can get 120-volt load out in this situation
it's corner grounded there's only 240-volt loads that can be served with this
another common thing that you're gonna see out in the field is a center-tapped Delta
and that just means that instead of tapping the corner where you've got
two of these windings that come together or two of these coils you're gonna tap
in the center of one of them and what that does is it gives you a halfway
point it gives you a way to split the difference of potential of one of these
and have two smaller differences in potential so you're still gonna have 240
volts across all of your coils, 240 between there and there, there and
there, there and there but because we just basically cut that coil in half
or we intercepted the halfway point of it, it allows us to get 120-volts out of
each side so this is really common, you're gonna see this a lot of like older
buildings even houses like there's places around here in Austin like old
Lake houses that we come across this three-phase four-wire
system where it has what we call a high leg or a wild leg and it's usually one
of the incoming wires that's coming up from the transformer it has orange tape
around it and the reason is we have standard voltages everywhere in the
system but look what happens when we try to take voltage between this and ground
so like from here to ground we get 120 here your ground we get 120 but what
happens from here to ground is you get 208
which is strange right like why but you need to understand that that's a single
phase voltage that's for one hot to ground you're getting 208-volts from one
black wire essentially to neutral or to ground and that's really dangerous a lot
of times people will hook up like lighting loads and things like that
and you'll just fry stuff because you're running 208-volts through that
piece of equipment that's only rated at 120 so understanding that you have a
high leg when you're working with a center tap Delta is like a really
crucial thing to understand if you ever see an orange conductor in with any
black blue or red conductors you need to like be on alert like oh this is there's
something different here and I need to be really careful usually that's on B
phase there's some utilities out there that likes it to be on C phase but
again just understand what it is it's super dangerous so the math behind how
that works and why that works there's a number that I've talked about before and
it's the "square-root of 3" (1.732) if you ever do calculations and three-phase
you're trying to calculate the size of a transformer or you're trying to figure
out kVA, power factor, a lot of these different things you have to use the
"square-root of 3" when you're multiplying things with you're trying to figure out
single-phase you don't have to do that but because of the ratio of these
windings and how three-phase operates you have to have this extra number that
we input into calculations and it's the square-root of 3 which equals 1.732
so if you ever look at voltage systems and you're looking
between your line and your neutral voltage if you multiply 120 times the
square root of 3 you're gonna get 208 so that's not an intended thing that
happens it's just kind of the byproduct of how this power is coming in how the
windings in that generator that's generating all of this power come
together and produce voltage so you get 208 it's the same thing if you look at a
Wye service say we've got a three-phase Wye we've got 208 oops
between each one of our winding so you've got 208, 208, 208
and we've got 120 between each to the center tapped ground it's the same
thing we have 120 between each one of these between this leg and ground this
leg and ground and this legging ground but if you take 120 times square root of
3 you get 208 so that's just to understand
how that number works 480-volts is the same way a lot of people that start
saying like ok well how the hell do you even get 277 versus 480 and if we look
at it just scratch all of these out say this is 480 480 and 480 well 277 times
the square root of 3 equals 480 and it actually probably equals like 479.25
something or other. But you get the idea and I don't just know that
that's something like you can do the inverse of it divide 480 divided by
1.732, you get 277 so that's where these weird numbers come from when you
see 208, 230, 240, 277 it kind of gets confusing and you're like well
which one is what and how are we doing this when you're actually out in the
field it's not really that difficult because you've got wires that are
certain colors if you're working with brown yellow and purple or brown orange
and yellow depending on what municipality you're working in you know
that that's a certain voltage system and that's gonna be 480/277v if you're
working with red black and blue you know that you're gonna be within you know the
120/240v range and that includes 208 as well so I hope that cleared it up
three-phase single-phase same thing you can still have 480-volt and 277-volt in
single-phase and in three-phase you can have 240/120v in three-phase and single
phase alright I hope that helps let me know if you guys have any other
questions if you have like very specific things that you want to know or you want
me to cover something a little bit better leave a comment below I love you
crazy [people] and I will see you in the next one.....BYE!
you