I posted this on the welding board as well, but someone recommended I
post here as well, since there are some electricians on this board. So
the post is below.

Well, I'm sure many read my post about wiring for a new welder and I
said I was going to run 6 guage wire(NM 6/3) from my Basement to my
Garage to hook up to a new Breaker Panel. This was going to be a 60
amp breaker in my basement to that Breaker Panel.

This has brought up some more questions in my mind.

I'm starting to wonder if 6 guage is safe for 60 amps? Or do I have to

get away from NM Wire and switch to Flexible Conduit and run a higher
amperage wire? Many times I see NM 6/3 recommend for 50 amps, but I
don't see many recommendations for 60 amps and higher for NM wire.
This wire will be about 70-80 feet, going through my Basement Ceiling,
up a finished wall, through my Garage Ceiling, and partially down a
Garage Wall.


This is everything that will be on the breaker box, with room for a
hair more.


Equip Voltage Amps Watts


Welder 230 27 6210
Compressor 230 20 4600
Tools Outlet 120 20 2400
Outdoor Lights 120 20 2400
Misc 120 15 1800


Total Watts 17410
First 10,000 Watts at 100% 10000
Remaining Watts at 40% 2964
Total Watts for AMP determination 12964


AMPS needed total watts / 230V 56.37


Thanks, James

3-wire 6 gauge ampacity is 55 amps for UF and 65 for THWN. At 50 amps, and
a 2% maximum voltage drop, you're limited to 105ft of #6 at 240V.

Since you're using a 60-amp breaker, I assume you shouldn't be drawing more
than 50amps, continuous, no? You call out 56+ amps. That's way too much
for a 60 amp magnetic breaker in continuous duty. OTOH, it is not too much
for the #6 wire.

LLoyd


"sparty" wrote in message
ps.com...
I posted this on the welding board as well, but someone recommended I
post here as well, since there are some electricians on this board. So
the post is below.

Well, I'm sure many read my post about wiring for a new welder and I
said I was going to run 6 guage wire(NM 6/3) from my Basement to my
Garage to hook up to a new Breaker Panel. This was going to be a 60
amp breaker in my basement to that Breaker Panel.

This has brought up some more questions in my mind.

I'm starting to wonder if 6 guage is safe for 60 amps? Or do I have to

get away from NM Wire and switch to Flexible Conduit and run a higher
amperage wire? Many times I see NM 6/3 recommend for 50 amps, but I
don't see many recommendations for 60 amps and higher for NM wire.
This wire will be about 70-80 feet, going through my Basement Ceiling,
up a finished wall, through my Garage Ceiling, and partially down a
Garage Wall.


This is everything that will be on the breaker box, with room for a
hair more.


Equip Voltage Amps Watts


Welder 230 27 6210
Compressor 230 20 4600
Tools Outlet 120 20 2400
Outdoor Lights 120 20 2400
Misc 120 15 1800


Total Watts 17410
First 10,000 Watts at 100% 10000
Remaining Watts at 40% 2964
Total Watts for AMP determination 12964


AMPS needed total watts / 230V 56.37


Thanks, James

Ok, I just don't see 4/3 NM-B at Home Depot or Lowes. And yes I
already knew I needed 4 lines, 2 hots, 1 neutral, 1 ground.

From my reading, you don't want more than a 2% drop in Voltage, so as
long as it is under 100 feet you are ok.

When you say 100A are you saying that is your main breaker panel that
you are running this from, or that is the size of the breaker you added
to your main breaker panel, to run to your new one?

Well when I calculated everything, it comes between 54 - 57 amps. That
is just based on whether I get a 20amp or 27amp welder not sure yet.
So I will just assume 57 amps. Now from my reading you shouldn't put
more than 80% on a breaker for total wattage. So I'm guessing I should
go with a 70 amp breaker instead.

Now what wire should I use, really comes into question :-) What is 4/3
NM-B rated for?

100A seems high for 4/3 NM-B, but the Electrician said that was fine?
Where did you get it from?

"sparty" wrote in message
oups.com...
Well when I calculated everything, it comes between 54 - 57 amps. That
is just based on whether I get a 20amp or 27amp welder not sure yet.
So I will just assume 57 amps. Now from my reading you shouldn't put
more than 80% on a breaker for total wattage. So I'm guessing I should
go with a 70 amp breaker instead.

Now what wire should I use, really comes into question :-) What is 4/3
NM-B rated for?

Google "ampacity of copper wire".

LLoyd

sparty sezz:
I posted this on the welding board as well, but someone recommended I
post here as well, since there are some electricians on this board.
So the post is below.

Well, I'm sure many read my post about wiring for a new welder and I
said I was going to run 6 guage wire(NM 6/3) from my Basement to my
Garage to hook up to a new Breaker Panel. This was going to be a 60
amp breaker in my basement to that Breaker Panel.

This has brought up some more questions in my mind.

I'm starting to wonder if 6 guage is safe for 60 amps? Or do I have
to

get away from NM Wire and switch to Flexible Conduit and run a higher
amperage wire? Many times I see NM 6/3 recommend for 50 amps, but I
don't see many recommendations for 60 amps and higher for NM wire.
This wire will be about 70-80 feet, going through my Basement Ceiling,
up a finished wall, through my Garage Ceiling, and partially down a
Garage Wall.


This is everything that will be on the breaker box, with room for a
hair more.


Equip Voltage Amps Watts


Welder 230 27 6210
Compressor 230 20 4600
Tools Outlet 120 20 2400
Outdoor Lights 120 20 2400
Misc 120 15 1800


Total Watts 17410
First 10,000 Watts at 100% 10000
Remaining Watts at 40% 2964
Total Watts for AMP determination 12964


AMPS needed total watts / 230V 56.37


Thanks, James

I'm no electrician, but I just did this recently under the guidance of one.
My run was similar: 230V, 70-80 ft, Mostly in basement. Differences: 100A,
partially outside (detached garage). In preparation for the project, I used
a couple of the calculators readily available online for calculating the
voltage drop. I input a couple of different wire gauge sizes and used this
data to make my wire size determination. I verified this with my
electrician.

I ended up using 4/3 NM-B with Ground. According to the electrician I was
working, 2 lines, 1 neutral, and ground because the sub-panel had to be
grounded to the main panel by code. In addition, I used buried conduit in
the stretch outside (12-15') and to get into the panel once inside the
garage since it is a concrete block structure. I was told that if I used
THHN that I would have to run it in conduit the entire length and I did not
want the additional headache of running conduit through the mess of a
basement ceiling I had to deal with.
--
Later,
D-Rog

sparty sezz:
Ok, I just don't see 4/3 NM-B at Home Depot or Lowes. And yes I
already knew I needed 4 lines, 2 hots, 1 neutral, 1 ground.

Try a real electrical supply...I would be suprised if they even have 6/3 (at
least my locals). It was spendy but worth it for my situation.

From my reading, you don't want more than a 2% drop in Voltage, so as
long as it is under 100 feet you are ok.

Sounds right for the drop recommendation but I haven't run your numbers...

When you say 100A are you saying that is your main breaker panel that
you are running this from, or that is the size of the breaker you
added to your main breaker panel, to run to your new one?

I added a 100A breaker in my main panel to supply my 100A sub-panel.
--
Later,
D-Rog

On 2 Feb 2006 11:00:13 -0800, "sparty" wrote:

Well when I calculated everything, it comes between 54 - 57 amps. That
is just based on whether I get a 20amp or 27amp welder not sure yet.
So I will just assume 57 amps. Now from my reading you shouldn't put
more than 80% on a breaker for total wattage. So I'm guessing I should
go with a 70 amp breaker instead.

Now what wire should I use, really comes into question :-) What is 4/3
NM-B rated for?
If you are going to use NM (romex) wire then it must be kept dry. And
NEVER run it through conduit. The emphasis never is from the book, not
me. 4 gauge is good for 70 amps.
ERS

Current ratings for wire is sort of voodoo-ish.

The current rating is not just based on copper gauge, but the type of
insulation AND the type of raceway (conduit) used AND the number of other
wires in sed raceway, as well as ambient temperature and permissible rise in
temperature, etc.
IOW, the concern is for *heat*. The new insulations that can tolerate more
heat bump up the current rating of the same copper gauge!

Imo, these ratings are conservative. The base rating is given in the NEC
(National Electric Code), w/ each municipality giving it their own spin.
NYC was ridiculously strict, at one time, and then lightened up a little.
For example, #8 THHN stranded wire, can *easily* handle 60-80 continuous
amps over a 50 ft run--gets slightly warm. But it is "rated" at about 45.

In the very old days, the wires from the pole to the house were run *bare*,
for maximum current-carrying capacity. Tough on the squirrels, tho.

OTOH, doesn't hurt to have extra capacity, esp. for things like electric
heaters, lighting, the occasional microwave, fridge, etc. Thus, the
"incidental load" can be pretty substantial, depending depending.
On a cold day, my shop can be drawing 30 A (at 120V) before I've turned on a
single machine!
And, if I'm going to be using the welder at full tilt, occasionally I'll
turn a few things off, or make sure the dishwasher/dryer/etc. are off in the
house.

#4 Wi
Apropos of the above, the rating varies from 70 A to 278 A!! 1996 NEC.
Now, the 278 amp rating was for *nickel* covered wire (apropos of the thread
Surprises about electrical conductivity--nickel apparently is Da Bomb,
rating-wise!), but even w/o nickel, #4 wire can be rated up to 220!
Typically, tho, the rating for #4 hovers around 100, up to about 140-160.
Most local codes, and the NEC, for, say, two #4/one #8-10 (neutral)/one #12
(grnd) in a 1" pipe would be 80-100 amps.

Which, again, is very conservative, imo.
But, running larger wire--even considerably larger--is a cheap way to
prepare for the future.
You may even want to run an extra wire in the conduit for a third phase,
depending on where you might place a rotary phase converter.
--
Mr. P.V.'d
formerly Droll Troll
"sparty" wrote in message
oups.com...
100A seems high for 4/3 NM-B, but the Electrician said that was fine?
Where did you get it from?

"Eric R Snow" wrote in message
...
On 2 Feb 2006 11:00:13 -0800, "sparty" wrote:

Well when I calculated everything, it comes between 54 - 57 amps. That
is just based on whether I get a 20amp or 27amp welder not sure yet.
So I will just assume 57 amps. Now from my reading you shouldn't put
more than 80% on a breaker for total wattage. So I'm guessing I should
go with a 70 amp breaker instead.

Now what wire should I use, really comes into question :-) What is 4/3
NM-B rated for?
If you are going to use NM (romex) wire then it must be kept dry. And
NEVER run it through conduit. The emphasis never is from the book, not
me.

I don't see why not. I"ve seen HVAC peeple run romex thru conduit, lots of
times, esp. where nail puncture is a possibility.
Heat dissipation, mebbe?? That's all I can think of.
--
Mr. P.V.'d
formerly Droll Troll


4 gauge is good for 70 amps.
ERS

Ok, I just got off the phone with a local city inspector to verify. He
said that between 50 - 60 amps, 6/3 NM-B is fine. For over 60 amps up
to 100 amps, then they mandate you run 4/3 NM-B wire. He did say also,
if running through my basement ceiling, the holes in the joists must be
a mininum of 1 1/2 inches from the bottom. I guess that is incase you
finish the ceiling and nail/screw drywall in.

So I will be putting in a 70 amp breaker and running 4/3 NM-B to the
new breaker panel in the garage.

"sparty" wrote in message
ps.com...
Ok, I just got off the phone with a local city inspector to verify. He
said that between 50 - 60 amps, 6/3 NM-B is fine. For over 60 amps up
to 100 amps, then they mandate you run 4/3 NM-B wire. He did say also,
if running through my basement ceiling, the holes in the joists must be
a mininum of 1 1/2 inches from the bottom. I guess that is incase you
finish the ceiling and nail/screw drywall in.

NEC sez that wires closer than 1-1/2'' from a member surface require nailing
plates. It's just a steel guard to prevent nailing into a wire. Simpson and
others make them. Most have prongs to fasten, so you don't even need
fasteners.

LLoyd

He did say also, if running through my basement ceiling,
the holes in the joists must be a mininum of 1 1/2 inches
from the bottom.

As an aside, the other issue here is that the closer to the
bottom of a beam or joist you put the hole, the more it is
weakenned, since that's where there's the most tension.
If you put the holes through the center of the joist, it has
the least effect on the structure...

--Glenn Lyford

"sparty" wrote in news:1138904022.539979.6640
@z14g2000cwz.googlegroups.com:



AMPS needed total watts / 230V 56.37


Sparty,
A branch circuit has to be rated 125% of maximum expected (calculated)
load. This is 70 Amps for your 56 amp load. This gets you into the 4
gauge wire size. You can still run the 60 amp breaker in the main panel
if you wish, but your wire will be rated nearer to 80 in free air,
depending on the insulation type.

--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

Here we go again - what does ampacity mean ? - amp capacity ? Current Capacity ?
I can understand that in jargon and talk - but printed on boxes and breakers - that is
out of science.

Martin

Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH & Endowment Member
NRA Second Amendment Task Force Charter Founder



Lloyd E. Sponenburgh wrote:
3-wire 6 gauge ampacity is 55 amps for UF and 65 for THWN. At 50 amps, and
a 2% maximum voltage drop, you're limited to 105ft of #6 at 240V.

Since you're using a 60-amp breaker, I assume you shouldn't be drawing more
than 50amps, continuous, no? You call out 56+ amps. That's way too much
for a 60 amp magnetic breaker in continuous duty. OTOH, it is not too much
for the #6 wire.

LLoyd


"sparty" wrote in message
ps.com...

I posted this on the welding board as well, but someone recommended I
post here as well, since there are some electricians on this board. So
the post is below.

Well, I'm sure many read my post about wiring for a new welder and I
said I was going to run 6 guage wire(NM 6/3) from my Basement to my
Garage to hook up to a new Breaker Panel. This was going to be a 60
amp breaker in my basement to that Breaker Panel.

This has brought up some more questions in my mind.

I'm starting to wonder if 6 guage is safe for 60 amps? Or do I have to

get away from NM Wire and switch to Flexible Conduit and run a higher
amperage wire? Many times I see NM 6/3 recommend for 50 amps, but I
don't see many recommendations for 60 amps and higher for NM wire.
This wire will be about 70-80 feet, going through my Basement Ceiling,
up a finished wall, through my Garage Ceiling, and partially down a
Garage Wall.


This is everything that will be on the breaker box, with room for a
hair more.


Equip Voltage Amps Watts


Welder 230 27 6210
Compressor 230 20 4600
Tools Outlet 120 20 2400
Outdoor Lights 120 20 2400
Misc 120 15 1800


Total Watts 17410
First 10,000 Watts at 100% 10000
Remaining Watts at 40% 2964
Total Watts for AMP determination 12964


AMPS needed total watts / 230V 56.37


Thanks, James





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Yep like I said, since I figure a max of 57 amps, I divided the by 0.8
to make sure I was only running 80% safe capacity. So that's why i'm
chosing 70 amp breaker in my main panel. And yes, like I mentioned I
will be running 4/3 NM-B Wire.

Not sure what you mean by 80 in free air.

On 2 Feb 2006 19:58:56 -0800, "sparty" wrote:

Yep like I said, since I figure a max of 57 amps, I divided the by 0.8
to make sure I was only running 80% safe capacity. So that's why i'm
chosing 70 amp breaker in my main panel. And yes, like I mentioned I
will be running 4/3 NM-B Wire.

Not sure what you mean by 80 in free air.
What it means is that the wire, with insulation, is exposed to the air
all around, or virtually all around. This keeps the wire cool. The
wire itself can stand to be very hot but the insulation, depending on
type, has varying degrees of temperature resistance. This why the
Romex type of cable is not to be run inside conduit. The insulation
can eventually break down and allow the wires to touch each other or
the conduit and/or the insulation can catch fire. The ratings are
conservative. I believe this is because people tend to push things.
ERS

Martin H. Eastburn wrote:

Here we go again - what does ampacity mean ? - amp capacity ? Current
Capacity ?
I can understand that in jargon and talk - but printed on boxes and
breakers - that is
out of science.

Martin

Yep. Been in use in the electrician trade for at least 25 or 30
years.
...lew...

What if this is being run inside a wall? And there is insulation there?

"sparty" wrote in
oups.com:

What if this is being run inside a wall? And there is insulation
there?


Sparty,
Use #4 wire rated for about 70C and you will be fine. I don't have my
NEC handy to check which type. The NEC tables list current capacity in
free air, basically meaning the wire is hanging in ambient air. You have
to derate the current capacity when you put it in an enclosed space,
such as a wall. Hence my suggestion to go to #4, which should be plenty
safe for 70 amps in a wall.


--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

Eric R Snow wrote:


If you are going to use NM (romex) wire then it must be
kept dry. And NEVER run it through conduit.


It's OK to run NM cable through conduit according to the
2005 NEC. As I understand it, it was prohibited in an
earlier edition of the NEC because of a mistake. See 358.22
for EMT, "Cables shall be permitted to be installed where
such use is not prohibited by the respective cable
articles," and similar wording in other conduit articles.

Conduit used for Romex may need to be larger than if
individual wires were run. See Chapter 9, Table 1, Note 9
for percentage fill calculations.

--
-- Steve

Anthony and Steve thanks.

I have already decided to run #4 wire(4/3 NM-B), since this will be a
70 amp breaker. I will be putting a max load of about 56-57 amps that
will hook up to the new breaker panel. I just wanted to make sure #4
wire didn't get hot since it WILL be touching the paper portion of the
insulation. I'm assuming that wire doesn't get hot, unless you are
running more around 100 amps through it. Can someone confirm my
assumption? It will be quite difficult anyhow to run conduit through
the finished wall portion.

Thanks.

On Fri, 03 Feb 2006 23:43:00 -0800, Steve wrote:

Eric R Snow wrote:


If you are going to use NM (romex) wire then it must be
kept dry. And NEVER run it through conduit.


It's OK to run NM cable through conduit according to the
2005 NEC. As I understand it, it was prohibited in an
earlier edition of the NEC because of a mistake. See 358.22
for EMT, "Cables shall be permitted to be installed where
such use is not prohibited by the respective cable
articles," and similar wording in other conduit articles.

Conduit used for Romex may need to be larger than if
individual wires were run. See Chapter 9, Table 1, Note 9
for percentage fill calculations.
My copy of the NEC is not the 2005 ed. It's pretty new but things do
change. My house plans need to be re-engineered because the code has
changed.
ERS