I am in the thinking it out stage of re-wiring my house. I know my
bank balance will drop with the current price of copper but will my
voltage? The house is two-story standard construction with an
unfinished basement and attic access, the breaker box is in the
basement. My goal is disturb as little drywall as possible. The
furthest run will be to an upstairs bedroom.

Rough calculations give me:
50' to the other side of house
30' to first outlet (up to attic and drop to outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet - 6 outlets in room)
205' total estimated feet of wire.

Will voltage drop be a problem using 14/2 wire on a bedroom circuit
205' feet from the panel?

A friend who will be helping me suggested I put a sub panel on the
second floor to cut back on the amount of wire run. While this may be
true I'm not that thrilled with this idea. Main reason being I assume
the inspector will want the sub panel in an accessable area (not a
closet) that will require a 'decorative' picture. Any thoughts on
this?

in a word, yes.
firstly, I assume you have 15amp circuits throught, which should only
run 30' on a #14wire to keep under a 2% drop. Even with 10 amp ciruits
you shouln't go over 45'

heck jumping to #12 wire won't do it at that distance either, I would
recomend following your friends advice.

Empress2454 #124457


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RayV wrote:
I am in the thinking it out stage of re-wiring my house. I know my
bank balance will drop with the current price of copper but will my
voltage? The house is two-story standard construction with an
unfinished basement and attic access, the breaker box is in the
basement. My goal is disturb as little drywall as possible. The
furthest run will be to an upstairs bedroom.

Rough calculations give me:
50' to the other side of house
30' to first outlet (up to attic and drop to outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet - 6 outlets in room)
205' total estimated feet of wire.

Will voltage drop be a problem using 14/2 wire on a bedroom circuit
205' feet from the panel?

A friend who will be helping me suggested I put a sub panel on the
second floor to cut back on the amount of wire run. While this may be
true I'm not that thrilled with this idea. Main reason being I assume
the inspector will want the sub panel in an accessable area (not a
closet) that will require a 'decorative' picture. Any thoughts on
this?

wrote:

in a word, yes. firstly, I assume you have 15amp circuits throught,
which should only run 30' on a #14wire to keep under a 2% drop.

snip

Are you certain about the 30 feet? That wouldn't even get me to the
far side of the first floor for one outlet.

According to RayV :

wrote:

in a word, yes. firstly, I assume you have 15amp circuits throught,
which should only run 30' on a #14wire to keep under a 2% drop.

snip

Are you certain about the 30 feet? That wouldn't even get me to the
far side of the first floor for one outlet.

Yes, 30 feet is more than a bit extreme.

30' of #14 (approx 1 ohm/1000') has a voltage drop of about .96V at 15A.
Which is 1%. At 2%, that's 60'.

Our codes consider a 3-4% drop permissible - I don't think the
NEC is any stricter. Which is over 100' at 15A.

But 200' is clearly too far.

I wouldn't think twice about using #14 (breakered at 15A) for a general
outlet circuit up to 120' or so, and branches to fixed lighting somewhat
longer. That said, if there's any fixed/heavy/motorized equipment on
it (including a garage door opener or A/C), I think somewhat differently.

You have a number of options to finesse this. Subpanels are nice, but
of course they have to be accessible. Using 12/3 to get two 15A
circuits (shared neutral) "most of the way" (you're talking 200+ feet)
and splitting at a box to 14ga is another.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Folks:

My copy of the NEC doesn't actually restrict the voltage drop for
residential
wiring, but recommends a 3.6v drop in the branch circuit and a 5v drop
including
both branch and feeder together 'for reasonable efficiency'. Seems to
me a
circuit coming right from the panel could use the 5v value. These
are both
for 120v circuits, by the way. (3% and 5% are the values given, I
think. I don't
have the book on me right now)

Using the 3.6 v value, you can run this much 2-wire cable to your
furthest
receptacle outlet:

15A - 64 ft. of 12 AWG or 40 ft. of 14 AWG
20A - 48 ft. of 12 AWG

Unfortunately this adds up pretty quick.

Using the 5 v value:

15A - 89 ft. of 12 AWG or 55.5 ft. of 14 AWG
20A - 66.5 ft of 12 AWG

I said 'receptacle' because it's not likely that a light would draw the
full 15A, and
it's easier to predict what the current will be. I don't think too many
residential
fixtures draw 1800 W.

Cordially yours:
A.P.M.F.

According to :
Folks:

My copy of the NEC doesn't actually restrict the voltage drop for
residential
wiring, but recommends a 3.6v drop in the branch circuit and a 5v drop
including
both branch and feeder together 'for reasonable efficiency'. Seems to
me a
circuit coming right from the panel could use the 5v value. These
are both
for 120v circuits, by the way. (3% and 5% are the values given, I
think. I don't
have the book on me right now)

When I wrote the electrical wiring FAQ, I believe it went this
way in the NEC: you were _permitted_ to have as much as a 5% drop
on a circuit, and the utility is similarly required to provide
you 240V at the panel +/- 5%. Which works out to the voltage
at an outlet being permitted to be as much as approx 9-10% less
than nominal.

Which is where the nomenclature of "110V" came about - the minimum
permissible outlet voltage given permissible voltage drop from
the nominal supply voltage.

This is not to say that you can't engineer _better_ than that.
Eg: circuits driving 1/4HP+ motors should be carefully considered
for example.

But a maximum 15A circuit run of 30' for #14 is ridiculously
short. You'd hardly get to use "normal wire sizes" anywhere
in a house, you'd almost always be derated a size or more.

[My calculations were based on 1 ohm/1000'. I misremembered, it's
2.575 ohms/1000'. #10 is 1.018 ohm/1000']
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

RayV wrote:
I am in the thinking it out stage of re-wiring my house. I know my
bank balance will drop with the current price of copper but will my
voltage? The house is two-story standard construction with an
unfinished basement and attic access, the breaker box is in the
basement. My goal is disturb as little drywall as possible. The
furthest run will be to an upstairs bedroom.

Rough calculations give me:
50' to the other side of house
30' to first outlet (up to attic and drop to outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet - 6 outlets in room)
205' total estimated feet of wire.

Will voltage drop be a problem using 14/2 wire on a bedroom circuit
205' feet from the panel?

A friend who will be helping me suggested I put a sub panel on the
second floor to cut back on the amount of wire run. While this may be
true I'm not that thrilled with this idea. Main reason being I assume
the inspector will want the sub panel in an accessable area (not a
closet) that will require a 'decorative' picture. Any thoughts on
this?


I wouldn't be so sure you can't put the subpanel
in a closet. I have a subpanel in my furnace room
which is basically a closet about 3 feet square.
Ask an inspector. Even if it is not permitted
where you live, there are places where you can put
it and simply cover it with a painting, a mirror,
or use your imagination.

Well, it all depends on what the circuit is. Most circuits only have a few
amps on them, so voltage drop is not a serious issue.

Somebody suggested 12/3. That will certainly help if you do have more than
a few amps. Without looking it up, it is maybe a third of the voltage drop
of 14/2 depending on how well you lay out your circuits.


"RayV" wrote in message
ups.com...
I am in the thinking it out stage of re-wiring my house. I know my
bank balance will drop with the current price of copper but will my
voltage? The house is two-story standard construction with an
unfinished basement and attic access, the breaker box is in the
basement. My goal is disturb as little drywall as possible. The
furthest run will be to an upstairs bedroom.

Rough calculations give me:
50' to the other side of house
30' to first outlet (up to attic and drop to outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet)
25' to next outlet (up to attic, over a few feet, and drop to next
outlet - 6 outlets in room)
205' total estimated feet of wire.

Will voltage drop be a problem using 14/2 wire on a bedroom circuit
205' feet from the panel?

A friend who will be helping me suggested I put a sub panel on the
second floor to cut back on the amount of wire run. While this may be
true I'm not that thrilled with this idea. Main reason being I assume
the inspector will want the sub panel in an accessable area (not a
closet) that will require a 'decorative' picture. Any thoughts on
this?

Will voltage drop be a problem using 14/2 wire on a bedroom circuit
205' feet from the panel?


I would think so. I use to have a simple program that would calculate
voltage drops in volts and in % drop so you don't need to look it up in a
table or calculated it. It ask for wire size (or R + jX if you have it) and
length, single or three phase, voltage, and power factor.

A friend who will be helping me suggested I put a sub panel on the
second floor to cut back on the amount of wire run. While this may be
true I'm not that thrilled with this idea. Main reason being I assume
the inspector will want the sub panel in an accessable area (not a
closet) that will require a 'decorative' picture. Any thoughts on
this?


We use to put in subpanels when there are a few runs (a few runs is subject
but a lot of runs, subpanel is the way to go) rather than home run
everything from the existing panel. Could be cleaner and cheaper but you'll
be the judge.