what's going on my friends i am dustin stelzer with electricianu and
we have a question and the question is next video can you delve into
why grounding conductors are often smaller than the ground did neutrals that they go
with thanks for the hard work you put into your channel you're welcome so let's break into it
let's just uh to start this out for those that don't know we'll go to article 100 let's read the
definitions of each one so that we all know what they are grounded conductor this is what we call
our neutral is a system or circuit conductor that is intentionally grounded that is not the same
thing as a ground that we call a ground out in the field the thing we call the ground out in the
field the bare conductor or the green conductor that's the equipment ground ding conductor
notice that there's an ing at the end equipment grounding and then there is ground did which is
the typically the neutral an equipment grounding conductor what we call the ground is a conductive
path or paths that is part of an effective ground fault current path and connects normally
non-current carrying metal parts of an equipment together to the system grounded conductor or
to the grounding electrode conductor or both so the equipment grounding conductor carries
fault current back to the grounded conductor or the grounding electrode conductor the one that
goes down to the ground rod or potentially both of them so there is a difference between them
a grounded conductor or neutral is designed to be a current carrying conductor meaning
that at all times it should have current on it now if you have like this whole theoretically
perfectly balanced system that we all seem to talk about in forums which never exists
if you if you balance everything out and all of the loads are even and every breaker count
is even and they have the exact same amount of uh amperage or current flowing through each one
of the breakers on each one of the phases and everything is perfectly in tune and equal and
balanced then yeah in some cases you're not going to have any neutral current there's not
going to be any current that's going to be flowing because there's no imbalance worth of current that
that neutral has to carry so in that case yes a neutral may not have any current on it but it is
still designed to carry current so a hot conductor has current going and hot and neutral together to
a light bulb they're both changing back and forth the electrons are getting excited there's current
actually traveling on it so it needs to be sized to carry that constant amount of current
it can usually be reduced in size because we know that once we start balancing things out
that it's not going to have the majority of the amount of current that all of the rest of
the conductors are if you balance the system well but it still needs to account for a large amount
of current flowing on it and flowing on it all the time you could also have situations where you have
non-linear loads you could have harmonics you could have things where there's going
to be an added amount of current in the neutral so you can't reduce the size of the neutral
um some you know like single family dwellings and stuff you can reduce the neutral size you can
run two hots of one size you can run a little bit smaller neutral usually like one size less that's
kind of a rule of thumb but it's not truth like you have there actually is calculations 70
values and things that you have to figure out in code for a neutral reduction but if you have
three-phase non-linear loads where you could have this added amount of current building up
on the neutral in excess of what each one of the ungrounded conductors or hots might have then you
need an upside upsized neutral another case where this would be the case is k-rated
transformers such are transformers out there that specifically rely on there being an an
excess amount of current flowing out of neutral so they actually make that conductor inside the
transformer a lot bigger to be able to handle a lot more heat and handle all those harmonic
currents that are going through it so neutral conductors or the grounded conductors are intended
to carry current and that's why they have to be big the equipment grounding conductor or ground
should not be carrying current on it it's really just a conductor that it has a conductive path
so if a fault happens it can carry that fault current momentarily very quick split second and
it turns off immediately so it's only going to carry current during a fault condition
and it should not be relied upon to carry current to keep a load running that's what the neutrals
for or that's what the two hots ungrounded conductors are for so the equipment grounding
conductor is a lot smaller because it's never intended to have current on it but if it does have
current it needs to be of sufficient size to be able to handle the fault current without damaging
the insulation around that conductor even if it is like a slightly sustained amount of ground
fault current if the car you know a long length or something where it's going to be like on and
energized for a second and then shut off so it has to be of sufficient size to be able to handle that
specific purpose so typically if you look at the values for conductors um a lot of people like old
school cats would be like well you just size your neutral one size less than your hots and then you
size your ground two sizes less than your hots and in some cases that's accurate but that's not
truth so equipment grounding conductors just again for those that are not in the know uh if we go to
article 250 in our national electrical code this is the 2020 code we're going to table 250.122.
article 250.122 talks about sizing equipment grounding conductors and just talks about
procedurally what to do everything with equipment grounded conductors specifically so for grounds
we are looking in table 250.122 and you'll notice that the size of the equipment grounding
conductors are based off of the breaker size so right we run a circuit from a breaker
out to a load we carry an equipment grounding conductor with those to that equipment we are
grounding that equipment so we're always sizing that conductor based off the breaker size
just like we do with the ungrounded conductors you know the hots or hots and neutrals we're
always sizing like number 12 or 12 awg wire off of a 20 amp breaker for the most part um
there's derating factors there's reasons why you might upsize or you know whatever but for the
majority of the time when we're running a number 12 conductor we're running it on a 20 amp breaker
the wire is figured out off the breaker size really off of the amount of current
going through it but we use that breaker size to determine whether or not the breaker and the
the wire actually match so same thing with the equipment ground that goes with them we use
the breaker so just remember grounds always go off the breaker feeding that piece of equipment
grounding electrodes are a little bit different so grounding electrodes are
sized not off the breaker size but they're sized off of the actual conductors coming
into the panel so if there's a fault if there's a the amount of available fault current at that
point because those are large conductors right those if they short out there's a
lot of current that can go through those before something crazy happens and so we need to have
a conductor that's based off of the available fault current that could happen at that location
not off of any breaker size so that's the differences between them but the neutral itself
is always going to be carrying current there is a part in 220.61 feeder and service neutral load so
if you do want to figure out how to reduce your neutral size or calculate your neutral size if
you want to reduce it if you can or if you can't all of that is going to be into 220.61
and that's specifically in the standard method there is also mention of using 220.61 to reduce
neutrals within the optional method as well it's still you're still able to do it you just have
to read a little bit about that but that is the reason because they're not the same thing a lot
of people think grounds and neutrals are the same thing the ground is just like a backup neutral
no neutral supposed to carry current all the time it's actually running loads it's
light bulbs running through it there's all kinds of current going through neutrals all the time
there are some instances where there might not be current flowing on a neutral because it's a
perfectly balanced system and then current is taking a different path to still complete the
current um but it's going through multiple loads so it's still the same amount of power that's
going through everything but for the majority of the time there is always going to be current on
that neutral and that's why it has to be bigger so let me know if you guys have any other questions
i'm going to keep doing videos all year long just going to the comments section and answering all
your cuts questions so get them while they're hot love you crazy people see you the next one
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