After many years of use the cord on my Sears table saw is running out of
space to wrap electrical tape around it. This is the cord from the
switch not the cord from the motor to the switch. The motor is a 1 hp,
120 volt. The instruction that came with the motor says that a 20 amp
fuse should be used in the circuit to which the motor is connected. (Yes
I am a pack rat)

Would a cord with 12 gauge wire be sufficient for the 6 foot replacement
cord, or would I use a smaller gauge wire.

I can find 14 and 16 gauge readily but 12 gauge is harder to find.

"Keith Nuttle" wrote in message
...
After many years of use the cord on my Sears table saw is running out of
space to wrap electrical tape around it. This is the cord from the switch
not the cord from the motor to the switch. The motor is a 1 hp, 120 volt.
The instruction that came with the motor says that a 20 amp fuse should be
used in the circuit to which the motor is connected. (Yes I am a pack rat)

Would a cord with 12 gauge wire be sufficient for the 6 foot replacement
cord, or would I use a smaller gauge wire.

I can find 14 and 16 gauge readily but 12 gauge is harder to find.


12ga is rated for 20 amps

basilisk

On 05/04/2010 04:04 PM, Lew Hodgett wrote:
Go to the electrical section of your favorite DIY and look for molded
cord sets

Buy a 6'-10', 10-2 with ground (black, white, green) extension cord.

Chop off the female end and wire into saw.

I agree with the concept, but I'd go with #12 instead of #10.

#10 is much harder to find in reasonable lengths around here, and is
significantly more expensive than #12.

Chris

On 5/4/2010 6:19 PM, Chris Friesen wrote:
On 05/04/2010 04:04 PM, Lew Hodgett wrote:
Go to the electrical section of your favorite DIY and look for molded
cord sets

Buy a 6'-10', 10-2 with ground (black, white, green) extension cord.

Chop off the female end and wire into saw.

I agree with the concept, but I'd go with #12 instead of #10.

#10 is much harder to find in reasonable lengths around here, and is
significantly more expensive than #12.

Chris

Thank you for the quick responses. I have spent the afternoon in
hardware stores, and one of the big box stores but could not find what I
was looking for. My plan was to do exactly what was suggested, buy a
short extension cord, cut of the female end, and wire it into the switch
box.

If all else fails, I will buy the cord and plug and make one myself.

At least I know I that I was right in not buying anything less than 12
gauge.

Keith Nuttle wrote:
....

... My plan was to do exactly what was suggested, buy a
short extension cord, cut of the female end, and wire it into the switch
box.

If all else fails, I will buy the cord and plug and make one myself.
....

Buy the long one and a plug. Use the molded plug end for the saw
section and put the store-bought plug on the remainder and you now have
a nice heavy duty extension cord besides.

--

On May 4, 5:52*pm, Keith Nuttle wrote:
After many years of use the cord on my Sears table saw is running out of
space to wrap electrical tape around it. *This is the cord from the
switch not the cord from the motor to the switch. *The motor is a 1 hp,
120 volt. *The instruction that came with the motor says that a 20 amp
fuse should be used in the circuit to which the motor is connected. (Yes
I am a pack rat)

Would a cord with 12 gauge wire be sufficient for the 6 foot replacement
cord, or would I use a smaller gauge wire.

I can find 14 and 16 gauge readily but 12 gauge is harder to find.

Rule of thumb is:
14 ga.=15 amps
12 ga.=20 amps
10 ga.=30 amps
8 or 6 ga.=50 amps. 6 ga. for long runs (stove w/baking)

RP

On 5/4/2010 7:03 PM, Keith Nuttle wrote:
On 5/4/2010 6:19 PM, Chris Friesen wrote:
On 05/04/2010 04:04 PM, Lew Hodgett wrote:
Go to the electrical section of your favorite DIY and look for molded
cord sets

Buy a 6'-10', 10-2 with ground (black, white, green) extension cord.

Chop off the female end and wire into saw.

I agree with the concept, but I'd go with #12 instead of #10.

#10 is much harder to find in reasonable lengths around here, and is
significantly more expensive than #12.

Chris

Thank you for the quick responses. I have spent the afternoon in
hardware stores, and one of the big box stores but could not find what I
was looking for. My plan was to do exactly what was suggested, buy a
short extension cord, cut of the female end, and wire it into the switch
box.

If all else fails, I will buy the cord and plug and make one myself.

At least I know I that I was right in not buying anything less than 12
gauge.

12 should be fine. If you want to use 10, look near the generators in
Lowes or Home Depot. The cords will have a twist-lock connector though
so you'll have to cut that off and put a regular one on, or else put in
a special outlet.

On May 4, 5:52*pm, Keith Nuttle wrote:
After many years of use the cord on my Sears table saw is running out of
space to wrap electrical tape around it. *This is the cord from the
switch not the cord from the motor to the switch. *The motor is a 1 hp,
120 volt. *The instruction that came with the motor says that a 20 amp
fuse should be used in the circuit to which the motor is connected. (Yes
I am a pack rat)

Would a cord with 12 gauge wire be sufficient for the 6 foot replacement
cord, or would I use a smaller gauge wire.

I can find 14 and 16 gauge readily but 12 gauge is harder to find.


Go to your local electrical supply house and get 6-10' of 12/3SJ
cord and a 15A 120V straight blade plug unless you have a 20A 120V
straight blade on there right now. The difference is a 15A has 2
prongs parallel to each w/ground and a 20A has the 2 prongs
perpendicular to each other w/ground.

The formula for ampacity when HP is known is:

HP x 746 / E x Eff x pf

Where E=Voltage
Eff=Efficiency (found on plate with voltage)
pf=Power Factor (also found on plate)


Wire size is limited by the plug. I suspect that you have a 15A plug
on there now so anything beyond 12 gauge wire is a waste.

Allen

12 is all you will need in that short length.
Martin

Keith Nuttle wrote:
After many years of use the cord on my Sears table saw is running out of
space to wrap electrical tape around it. This is the cord from the
switch not the cord from the motor to the switch. The motor is a 1 hp,
120 volt. The instruction that came with the motor says that a 20 amp
fuse should be used in the circuit to which the motor is connected. (Yes
I am a pack rat)

Would a cord with 12 gauge wire be sufficient for the 6 foot replacement
cord, or would I use a smaller gauge wire.

I can find 14 and 16 gauge readily but 12 gauge is harder to find.

Doug Miller wrote:
....

Again: if Sears says it's 1HP, it's probably really no more than 1/2 HP.
....

From '69, in all likelihood it is actually a 1-horse motor. That
antedates the "peak" HP period.

--

Keith Nuttle wrote:
After many years of use the cord on my Sears table saw is running out
of space to wrap electrical tape around it. This is the cord from the
switch not the cord from the motor to the switch. The motor is a 1
hp, 120 volt. The instruction that came with the motor says that a
20 amp fuse should be used in the circuit to which the motor is
connected. (Yes I am a pack rat)

Would a cord with 12 gauge wire be sufficient for the 6 foot
replacement cord, or would I use a smaller gauge wire.

I can find 14 and 16 gauge readily but 12 gauge is harder to find.

12 guage would indeed be sufficient. It is readily available at Home Depot,
Lowes, and all of the other suspects. Definitely not hard to find. An
alternative, if you're so inclined is to just buy a 12 ga extension cord,
cut off the female end, and wire it to your saw.

--

-Mike-

Keith Nuttle wrote:


Original Poster: The motor is a Sears 1 hp motor that came with the
10" table saw when it was purchased in 1969. It is a capacitor start
motor which for the first couple of microseconds draws a quite high
current.

Ok... and this means what? At least, to the discussion as it has progressed
at this point?

--

-Mike-

Keith Nuttle wrote:
After many years of use the cord on my Sears table saw is running out of
space to wrap electrical tape around it. This is the cord from the
switch not the cord from the motor to the switch. The motor is a 1 hp,
120 volt. The instruction that came with the motor says that a 20 amp
fuse should be used in the circuit to which the motor is connected. (Yes
I am a pack rat)

Would a cord with 12 gauge wire be sufficient for the 6 foot replacement
cord, or would I use a smaller gauge wire.

I can find 14 and 16 gauge readily but 12 gauge is harder to find.


Wire of the same gauge as that you are replacing should be sufficient.

--
Jack Novak
Buffalo, NY - USA

On May 5, 9:26*am, "Mike Marlow" wrote:
Keith Nuttle wrote:

Original Poster: * The motor is a Sears 1 hp motor that came with the
10" table saw when it was purchased in 1969. It is a capacitor start
motor which for the first couple of microseconds draws a quite high
current.

Ok... and this means what? *At least, to the discussion as it has progressed
at this point?

It means that the saw, when bogged down, may (or not) draw 6A. 14GA
is fine. Though I'd still go 12GA. ;-)

On 05/05/2010 09:29 AM, wrote:
On May 5, 9:26 am, "Mike Marlow" wrote:
Keith Nuttle wrote:

Original Poster: The motor is a Sears 1 hp motor that came with the
10" table saw when it was purchased in 1969. It is a capacitor start
motor which for the first couple of microseconds draws a quite high
current.

Ok... and this means what? At least, to the discussion as it has progressed
at this point?

It means that the saw, when bogged down, may (or not) draw 6A. 14GA
is fine. Though I'd still go 12GA. ;-)

You forgot about power factor and efficiency.

A good rule of thumb for most "normal" induction motors is 10A per HP at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A.

Chris

On May 5, 11:48*am, Chris Friesen wrote:
On 05/05/2010 09:29 AM, wrote:

On May 5, 9:26 am, "Mike Marlow" wrote:
Keith Nuttle wrote:

Original Poster: * The motor is a Sears 1 hp motor that came with the
10" table saw when it was purchased in 1969. It is a capacitor start
motor which for the first couple of microseconds draws a quite high
current.

Ok... and this means what? *At least, to the discussion as it has progressed
at this point?

It means that the saw, when bogged down, may (or not) draw 6A. *14GA
is fine. *Though I'd still go 12GA. *;-)

You forgot about power factor and efficiency.

The power factor of an induction motor is pretty close to unity at
full load.

A good rule of thumb for most "normal" induction motors is 10A per HP at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A.

My bet is that a "normal" motor isn't much less. There is more in
that motor than a few (more) pounds of copper (like a name plate).

Even at 10A, there is still a 60% safety factor with 14AWG and 100%
with 12AWG. Good 'nuff.

On 05/05/2010 10:59 AM, wrote:
On May 5, 11:48 am, Chris Friesen wrote:

A good rule of thumb for most "normal" induction motors is 10A per HP at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A.

My bet is that a "normal" motor isn't much less. There is more in
that motor than a few (more) pounds of copper (like a name plate).

I was curious, so I went and checked on Baldor's site.

I checked a few 3450rpm 1HP "general purpose" induction motors and the
FLA at 120V ranged from 11.8 to 15A. Worse than I thought.

Chris

On May 5, 12:30*pm, Chris Friesen wrote:
On 05/05/2010 10:59 AM, wrote:

On May 5, 11:48 am, Chris Friesen wrote:
A good rule of thumb for most "normal" induction motors is 10A per HP at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A.

My bet is that a "normal" motor isn't much less. *There is more in
that motor than a few (more) pounds of copper (like a name plate).

I was curious, so I went and checked on Baldor's site.

I checked a few 3450rpm 1HP "general purpose" induction motors and the
FLA at 120V ranged from 11.8 to 15A. *Worse than I thought. *

Gack! You're right. I looked up a few sites and found 12-15A for a
general purpose 1-HP 120V motor (I thought motors were far better than
50% efficient). Nothing less than 12AWG!

In article , " wrote:
On May 5, 12:30=A0pm, Chris Friesen wrote:
On 05/05/2010 10:59 AM, wrote:

On May 5, 11:48 am, Chris Friesen wrote:
A good rule of thumb for most "normal" induction motors is 10A per HP =
at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A.

My bet is that a "normal" motor isn't much less. =A0There is more in
that motor than a few (more) pounds of copper (like a name plate).

I was curious, so I went and checked on Baldor's site.

I checked a few 3450rpm 1HP "general purpose" induction motors and the
FLA at 120V ranged from 11.8 to 15A. =A0Worse than I thought. =A0

Gack! You're right. I looked up a few sites and found 12-15A for a
general purpose 1-HP 120V motor (I thought motors were far better than
50% efficient). Nothing less than 12AWG!

Why? 14AWG wire will safely carry 20A. The NEC limits the *overcurrent
protection* on a 14AWG circuit to 15A, but also specifically lists the
ampacity of 14AWG copper as 20A with 60degC and 75degC insulation, and 25A
with 90degC insulation. [2008 NEC, Table 310.16]

On May 5, 3:13*pm, (Doug Miller) wrote:
In article , " wrote:

On May 5, 12:30=A0pm, Chris Friesen wrote:
On 05/05/2010 10:59 AM, wrote:

On May 5, 11:48 am, Chris Friesen wrote:
A good rule of thumb for most "normal" induction motors is 10A per HP =
at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A..

My bet is that a "normal" motor isn't much less. =A0There is more in
that motor than a few (more) pounds of copper (like a name plate).

I was curious, so I went and checked on Baldor's site.

I checked a few 3450rpm 1HP "general purpose" induction motors and the
FLA at 120V ranged from 11.8 to 15A. =A0Worse than I thought. =A0

Gack! *You're right. *I looked up a few sites and found 12-15A for a
general purpose 1-HP 120V motor (I thought motors were far better than
50% efficient). *Nothing less than 12AWG!

Why? 14AWG wire will safely carry 20A. The NEC limits the *overcurrent
protection* on a 14AWG circuit to 15A, but also specifically lists the
ampacity of 14AWG copper as 20A with 60degC and 75degC insulation, and 25A
with 90degC insulation. [2008 NEC, Table 310.16]

At 15A it's getting too close to the limits. Add in the starting
current and 12AWG is clearly better. The cost difference is
insignificant, so no, I'd not use 14GA (and don't).

On May 5, 4:13*pm, (Doug Miller) wrote:
In article , " wrote:

On May 5, 12:30=A0pm, Chris Friesen wrote:
On 05/05/2010 10:59 AM, wrote:

On May 5, 11:48 am, Chris Friesen wrote:
A good rule of thumb for most "normal" induction motors is 10A per HP =
at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A..

My bet is that a "normal" motor isn't much less. =A0There is more in
that motor than a few (more) pounds of copper (like a name plate).

I was curious, so I went and checked on Baldor's site.

I checked a few 3450rpm 1HP "general purpose" induction motors and the
FLA at 120V ranged from 11.8 to 15A. =A0Worse than I thought. =A0

Gack! *You're right. *I looked up a few sites and found 12-15A for a
general purpose 1-HP 120V motor (I thought motors were far better than
50% efficient). *Nothing less than 12AWG!

Why? 14AWG wire will safely carry 20A. The NEC limits the *overcurrent
protection* on a 14AWG circuit to 15A, but also specifically lists the
ampacity of 14AWG copper as 20A with 60degC and 75degC insulation, and 25A
with 90degC insulation. [2008 NEC, Table 310.16]

Table 310.16 doesn't apply unless he is replacing the wiring going to
the receptacle that the saw is plugging into. You want to look at
Table 400.5(A) which is the allowable ampacity for flexible cables
(i.e. SJ,SO,SJE,etc.) which is the type of cable that he needs. Then
the limiting factor again is the receptacle/plug combination that he
has been using. If the saw had a 15A/120V plug on it, then 14ga. wire
would be acceptable. If it was a 20A/120V plug on it, then 12ga. would
be acceptable. Table 400.5(A) lists 14ga at 18A and 12 ga. at 25A.

I agree that the saw probably wouldn't draw more than 10A continuous
so anything beyond 14ga. is probably a waste at this point.

Allen

On Wed, 5 May 2010 10:12:30 -0400, "Mike Marlow"
wrote the following:

Keith Nuttle wrote:
After many years of use the cord on my Sears table saw is running out
of space to wrap electrical tape around it. This is the cord from the
switch not the cord from the motor to the switch. The motor is a 1
hp, 120 volt. The instruction that came with the motor says that a
20 amp fuse should be used in the circuit to which the motor is
connected. (Yes I am a pack rat)

Would a cord with 12 gauge wire be sufficient for the 6 foot
replacement cord, or would I use a smaller gauge wire.

I can find 14 and 16 gauge readily but 12 gauge is harder to find.

12 guage would indeed be sufficient. It is readily available at Home Depot,
Lowes, and all of the other suspects. Definitely not hard to find. An
alternative, if you're so inclined is to just buy a 12 ga extension cord,
cut off the female end, and wire it to your saw.

I got 90' of 12ga cable for my 240v items and wired them up to the new
outlets I installed for them. Now I can move all 3 around the shop, or
out into the driveway, with plenty of cord to spare. L6-20 twistlocks
went on the ends to keep 'em plugged. I think it cost about $75
total, including the 250' of 12/2/grounded Romex, 3 outlets, 3 plugs,
and the cable. I use the rest of the Romex to run lights into the
unfinished attic for the guys to install the HVAC. Carrier Infinity,
96% efficient, with A/C. I now have a conditioned shop. /smugness
Dual 16x20" furnace filters keep the dust out of the house and
equalize the air.

--
All national institutions of churches, whether Jewish, Christian,
or Turkish, appear to me no other than human inventions, set up
to terrify and enslave mankind, and monopolize power and profit.
--Thomas Paine

On May 4, 5:52*pm, Keith Nuttle wrote:


I can find 14 and 16 gauge readily but 12 gauge is harder to find.

Hey there, not to worry. For the six feet you are running to the wall
the original gauge will do (as it so far has done) fine. My gues is
that teh original cord was 14 gauge stranded and that such a
replacement would do you fine. No need to ask us, just take a section
of your old cord and strip it apart/down and count the wires and note
the colors and measure the wire gauge and be done with it.

Having said all that, LOWES and HD offer an "extension cord" intended
for an Air Conditioner that is likely 10GA (chop off the female end)
and may offer one or two that are 12GA and GOING DOWN never really
hurt anyone, right?

BTW, If you go long, you must go down!

Enjoy

On Jun 1, 6:00*am, wrote:
On Wed, 05 May 2010 20:13:39 GMT, (Doug Miller) wrote:
In article , " wrote:
On May 5, 12:30=A0pm, Chris Friesen wrote:
On 05/05/2010 10:59 AM, wrote:

On May 5, 11:48 am, Chris Friesen wrote:
A good rule of thumb for most "normal" induction motors is 10A per HP =
at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A.

My bet is that a "normal" motor isn't much less. =A0There is more in
that motor than a few (more) pounds of copper (like a name plate).

I was curious, so I went and checked on Baldor's site.

I checked a few 3450rpm 1HP "general purpose" induction motors and the
FLA at 120V ranged from 11.8 to 15A. =A0Worse than I thought. =A0

Gack! *You're right. *I looked up a few sites and found 12-15A for a
general purpose 1-HP 120V motor (I thought motors were far better than
50% efficient). *Nothing less than 12AWG!

Why? 14AWG wire will safely carry 20A. The NEC limits the *overcurrent
protection* on a 14AWG circuit to 15A, but also specifically lists the
ampacity of 14AWG copper as 20A with 60degC and 75degC insulation, and 25A
with 90degC insulation. [2008 NEC, Table 310.16]

A one horsepower motor is always 748 Watts,

Must be nice to live in a perfect world, where everything is perfectly
efficient.

so you're "rule of thumb" is 120v x
10A = 1200watts, a bit on the high side of one HP. *In the past, manufacturers
would sometimes get carried away trying to show that their motors were better
than the competitions by making statements like "it DEVELOPS xx horsepower"
which was a far cry from it's real HP when you calculated it from the current
and voltage clearly marked on the nameplate.

Even better, perpetual motion is everyday, in your world.

*Almost all compressor
manufacturers were guilty of this type of deception. *Finally the FEDS stepped
in and threatened to start fining these companys for false advertising. You
cannot have a motor that draws 15a at 220v produce 5 hp and be telling the
truth. *They sure confused everyone so much that misunderstandings continue to
exist, but there is certainly no magic and it is pretty basic. *

Tell that to Sears.

On Tue, 01 Jun 2010 04:00:38 -0700, wrote:

On Wed, 05 May 2010 20:13:39 GMT, (Doug Miller) wrote:

In article , " wrote:
On May 5, 12:30=A0pm, Chris Friesen wrote:
On 05/05/2010 10:59 AM, wrote:

On May 5, 11:48 am, Chris Friesen wrote:
A good rule of thumb for most "normal" induction motors is 10A per HP =
at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A.

My bet is that a "normal" motor isn't much less. =A0There is more in
that motor than a few (more) pounds of copper (like a name plate).

I was curious, so I went and checked on Baldor's site.

I checked a few 3450rpm 1HP "general purpose" induction motors and the
FLA at 120V ranged from 11.8 to 15A. =A0Worse than I thought. =A0

Gack! You're right. I looked up a few sites and found 12-15A for a
general purpose 1-HP 120V motor (I thought motors were far better than
50% efficient). Nothing less than 12AWG!

Why? 14AWG wire will safely carry 20A. The NEC limits the *overcurrent
protection* on a 14AWG circuit to 15A, but also specifically lists the
ampacity of 14AWG copper as 20A with 60degC and 75degC insulation, and 25A
with 90degC insulation. [2008 NEC, Table 310.16]

A one horsepower motor is always 748 Watts, so you're "rule of thumb" is 120v x
10A = 1200watts, a bit on the high side of one HP. In the past, manufacturers
would sometimes get carried away trying to show that their motors were better
than the competitions by making statements like "it DEVELOPS xx horsepower"
which was a far cry from it's real HP when you calculated it from the current
and voltage clearly marked on the nameplate. Almost all compressor
manufacturers were guilty of this type of deception. Finally the FEDS stepped
in and threatened to start fining these companys for false advertising. You
cannot have a motor that draws 15a at 220v produce 5 hp and be telling the
truth. They sure confused everyone so much that misunderstandings continue to
exist, but there is certainly no magic and it is pretty basic.


Don't forget power factor in your formula or you'll have trouble
starting some motors or be surprised at what the actual current is.

Mike M

Quite a few technical electrical errors there but you concept is almost
correct.
A one HP motor make use of 748 Watts, not consumes.
120v X 10A = 1200va not watts
Many 1/4HP furnace motors take about 10A at 120volts. How do you figure that
one?


The new 5HP motors are including the inertia of the rotor and do not specify
"how long" they can deliver that HP.

E.G. Stand in front of a child on bicycle paddling as fast as he can and let
the impact on your groin stop it.
Feels like more than 5HP right? ...and yet, a seasoned cyclist can only
produce about 1/2 HP on a racing bike.

Yup, it's the way of our advertising world. You define something and we'll
find holes in it to twist the facts.



wrote in message
...
On Wed, 05 May 2010 20:13:39 GMT, (Doug Miller) wrote:
A one horsepower motor is always 748 Watts, so you're "rule of thumb" is
120v x
10A = 1200watts, a bit on the high side of one HP. In the past,
manufacturers
would sometimes get carried away trying to show that their motors were
better
than the competitions by making statements like "it DEVELOPS xx horsepower"
which was a far cry from it's real HP when you calculated it from the
current
and voltage clearly marked on the nameplate. Almost all compressor
manufacturers were guilty of this type of deception. Finally the FEDS
stepped
in and threatened to start fining these companys for false advertising. You
cannot have a motor that draws 15a at 220v produce 5 hp and be telling the
truth. They sure confused everyone so much that misunderstandings continue
to
exist, but there is certainly no magic and it is pretty basic.




In article
,
" wrote:
On May 5, 12:30=A0pm, Chris Friesen wrote:
On 05/05/2010 10:59 AM, wrote:

On May 5, 11:48 am, Chris Friesen wrote:
A good rule of thumb for most "normal" induction motors is 10A per HP
=
at
120V.

Higher quality motors can do better, of course, but a "premium
efficiency" 1HP Baldor motor that costs $500 is still rated at 8.6A.

My bet is that a "normal" motor isn't much less. =A0There is more in
that motor than a few (more) pounds of copper (like a name plate).

I was curious, so I went and checked on Baldor's site.

I checked a few 3450rpm 1HP "general purpose" induction motors and the
FLA at 120V ranged from 11.8 to 15A. =A0Worse than I thought. =A0

Gack! You're right. I looked up a few sites and found 12-15A for a
general purpose 1-HP 120V motor (I thought motors were far better than
50% efficient). Nothing less than 12AWG!

Why? 14AWG wire will safely carry 20A. The NEC limits the *overcurrent
protection* on a 14AWG circuit to 15A, but also specifically lists the
ampacity of 14AWG copper as 20A with 60degC and 75degC insulation, and 25A
with 90degC insulation. [2008 NEC, Table 310.16]




--- news://freenews.netfront.net/ - complaints: ---

On Tue, 1 Jun 2010 14:25:33 -0400, "Josepi" wrote:

Quite a few technical electrical errors there but you concept is almost
correct.
A one HP motor make use of 748 Watts, not consumes.

Nope. A 1-HP motor *delivers* one horsepower of mechanical power
(550ft lbs/second). Only a 100% efficient motor would require only 748W (BTW,
"watts" is not capitalized).

120v X 10A = 1200va not watts
Many 1/4HP furnace motors take about 10A at 120volts. How do you figure that
one?

I don't believe you. A 1HP motor may require 1200W at full load, but not a
1/4HP motor.

The new 5HP motors are including the inertia of the rotor and do not specify
"how long" they can deliver that HP.

Nope. Well, maybe Crapsman's HP rating. ;-)

E.G. Stand in front of a child on bicycle paddling as fast as he can and let
the impact on your groin stop it.
Feels like more than 5HP right? ...and yet, a seasoned cyclist can only
produce about 1/2 HP on a racing bike.

Silly.

Yup, it's the way of our advertising world. You define something and we'll
find holes in it to twist the facts.

....until someone puts a stop to the practice.
snip

On Tue, 01 Jun 2010 20:36:38 -0500, "
wrote:

On Tue, 1 Jun 2010 14:25:33 -0400, "Josepi" wrote:

Quite a few technical electrical errors there but you concept is almost
correct.
A one HP motor make use of 748 Watts, not consumes.

Nope. A 1-HP motor *delivers* one horsepower of mechanical power
(550ft lbs/second). Only a 100% efficient motor would require only 748W (BTW,
"watts" is not capitalized).

120v X 10A = 1200va not watts
Many 1/4HP furnace motors take about 10A at 120volts. How do you figure that
one?

I don't believe you. A 1HP motor may require 1200W at full load, but not a
1/4HP motor.

It can draw 1200 watts at startup. Not terribly uncommon. When
rotating, a whole lot less.

The new 5HP motors are including the inertia of the rotor and do not specify
"how long" they can deliver that HP.

Nope. Well, maybe Crapsman's HP rating. ;-)

Foot lbs torque @ rpm- a heavy rotor or flywheel CAN deliver
significant horsepower for a matter of seconds - after it has been
brought up to speed. In SOME applications, a heavy flywheel will alow
a much smaller than normal motor to do the job.

E.G. Stand in front of a child on bicycle paddling as fast as he can and let
the impact on your groin stop it.
Feels like more than 5HP right? ...and yet, a seasoned cyclist can only
produce about 1/2 HP on a racing bike.

Silly.

Yup, it's the way of our advertising world. You define something and we'll
find holes in it to twist the facts.

...until someone puts a stop to the practice.
snip

Your comments are mostly from poor reading comprehension of what I posted
and a lack of basic electrical.

Perhaps some electrical theory study and/or experience would help.

You jumped so high (OCD medication need renewing?) you got none of them
right, this time.


wrote in message
...
On Tue, 1 Jun 2010 14:25:33 -0400, "Josepi" wrote:

Quite a few technical electrical errors there but you concept is almost
correct.
A one HP motor make use of 748 Watts, not consumes.

Nope. A 1-HP motor *delivers* one horsepower of mechanical power
(550ft lbs/second). Only a 100% efficient motor would require only 748W
(BTW,
"watts" is not capitalized).

120v X 10A = 1200va not watts
Many 1/4HP furnace motors take about 10A at 120volts. How do you figure
that
one?

I don't believe you. A 1HP motor may require 1200W at full load, but not a
1/4HP motor.

The new 5HP motors are including the inertia of the rotor and do not
specify
"how long" they can deliver that HP.

Nope. Well, maybe Crapsman's HP rating. ;-)

E.G. Stand in front of a child on bicycle paddling as fast as he can and
let
the impact on your groin stop it.
Feels like more than 5HP right? ...and yet, a seasoned cyclist can only
produce about 1/2 HP on a racing bike.

Silly.

Yup, it's the way of our advertising world. You define something and we'll
find holes in it to twist the facts.

....until someone puts a stop to the practice.
snip



--- news://freenews.netfront.net/ - complaints: ---

On Tue, 01 Jun 2010 22:11:40 -0400, wrote:

On Tue, 01 Jun 2010 20:36:38 -0500, "
wrote:

On Tue, 1 Jun 2010 14:25:33 -0400, "Josepi" wrote:

Quite a few technical electrical errors there but you concept is almost
correct.
A one HP motor make use of 748 Watts, not consumes.

Nope. A 1-HP motor *delivers* one horsepower of mechanical power
(550ft lbs/second). Only a 100% efficient motor would require only 748W (BTW,
"watts" is not capitalized).

120v X 10A = 1200va not watts
Many 1/4HP furnace motors take about 10A at 120volts. How do you figure that
one?

I don't believe you. A 1HP motor may require 1200W at full load, but not a
1/4HP motor.

It can draw 1200 watts at startup. Not terribly uncommon. When
rotating, a whole lot less.

Agreed.

The new 5HP motors are including the inertia of the rotor and do not specify
"how long" they can deliver that HP.

Nope. Well, maybe Crapsman's HP rating. ;-)

Foot lbs torque @ rpm- a heavy rotor or flywheel CAN deliver
significant horsepower for a matter of seconds - after it has been
brought up to speed. In SOME applications, a heavy flywheel will alow
a much smaller than normal motor to do the job.

Ok, but that's not the way motors are rated or HP is calculated.

...

On Tue, 1 Jun 2010 22:48:57 -0400, "Josepi" wrote:

Your comments are mostly from poor reading comprehension of what I posted
and a lack of basic electrical.

You're clueless.

Perhaps some electrical theory study and/or experience would help.

Indeed it would. You should try it.

You jumped so high (OCD medication need renewing?) you got none of them
right, this time.

Nice deflection, but the *fact* is that you're full of **** (notice the lack
of defense).

In article ,
Josepi wrote:
A one HP motor make use of 748 Watts, not consumes.

Curious! When I was at school I was taught that 1hp=746w

Stuart wrote in
:

In article ,
Josepi wrote:
A one HP motor make use of 748 Watts, not consumes.

Curious! When I was at school I was taught that 1hp=746w



Perhaps it's the difference between US and British Horsepower... Our
pints are different, why not our horsepower?

Actually... According to "Pocket Ref" you're right:

1 HP (mech) = 745.7W
1 HP (electric) = 746W
1 HP (metric[!]) = 735.499W

Puckdropper
--
Never teach your apprentice everything you know.

On Tue, 01 Jun 2010 22:06:49 -0500, "
wrote:

On Tue, 01 Jun 2010 22:11:40 -0400, wrote:

On Tue, 01 Jun 2010 20:36:38 -0500, "
wrote:

On Tue, 1 Jun 2010 14:25:33 -0400, "Josepi" wrote:

Quite a few technical electrical errors there but you concept is almost
correct.
A one HP motor make use of 748 Watts, not consumes.

Nope. A 1-HP motor *delivers* one horsepower of mechanical power
(550ft lbs/second). Only a 100% efficient motor would require only 748W (BTW,
"watts" is not capitalized).

120v X 10A = 1200va not watts
Many 1/4HP furnace motors take about 10A at 120volts. How do you figure that
one?

I don't believe you. A 1HP motor may require 1200W at full load, but not a
1/4HP motor.

It can draw 1200 watts at startup. Not terribly uncommon. When
rotating, a whole lot less.

Agreed.

The new 5HP motors are including the inertia of the rotor and do not specify
"how long" they can deliver that HP.

Nope. Well, maybe Crapsman's HP rating. ;-)

Foot lbs torque @ rpm- a heavy rotor or flywheel CAN deliver
significant horsepower for a matter of seconds - after it has been
brought up to speed. In SOME applications, a heavy flywheel will alow
a much smaller than normal motor to do the job.

Ok, but that's not the way motors are rated or HP is calculated.

...
which are you dissagreeing with?
Horsepower is measured as foot/lbs per second - RPM X Ft Lbs
Torque/5252 is horsepower. Period.
And a heavy flywheel will allow a small motor to provide significantly
inproved torque for cyclic loads - making, is some cases, a 1/4 horse
motor do the job a 3 horse motor could not do without a flywheel.
Scaled up that's how punch presses work.

One electric HP is 745 watts, more or less - but to produce that 1 HP
with a motor of 80% efficiency requires 931 watts. And 80% isn't bad
for a "consumer equipment" motor.

And a series wound motor rated at, say 1 HP constant, may be able to
produce upwards of 4HP or more for periods of up to several minutes,
depending on it's thermal mass, and for duty cycles of up to say 15
or 20%. So that motor, rated at continuous service, is a 1HP motor,
and at cyclic service, perhaps legitimately 4 HP.

That said - if it is a 115 volt motor, running on a 15 amp circuit, it
is NOT more than a 2 HP motor - definitely - and more likely not more
than 1.5 if starting under no load or with a slow-trip breaker.
Generally not more than 1 HP if it starts a load on a standard trip
breaker or fuse.

On Wed, 02 Jun 2010 21:26:25 -0400, wrote:

On Tue, 01 Jun 2010 22:06:49 -0500, "
wrote:

On Tue, 01 Jun 2010 22:11:40 -0400, wrote:

On Tue, 01 Jun 2010 20:36:38 -0500, "
wrote:

On Tue, 1 Jun 2010 14:25:33 -0400, "Josepi" wrote:

Quite a few technical electrical errors there but you concept is almost
correct.
A one HP motor make use of 748 Watts, not consumes.

Nope. A 1-HP motor *delivers* one horsepower of mechanical power
(550ft lbs/second). Only a 100% efficient motor would require only 748W (BTW,
"watts" is not capitalized).

120v X 10A = 1200va not watts
Many 1/4HP furnace motors take about 10A at 120volts. How do you figure that
one?

I don't believe you. A 1HP motor may require 1200W at full load, but not a
1/4HP motor.

It can draw 1200 watts at startup. Not terribly uncommon. When
rotating, a whole lot less.

Agreed.

The new 5HP motors are including the inertia of the rotor and do not specify
"how long" they can deliver that HP.

Nope. Well, maybe Crapsman's HP rating. ;-)

Foot lbs torque @ rpm- a heavy rotor or flywheel CAN deliver
significant horsepower for a matter of seconds - after it has been
brought up to speed. In SOME applications, a heavy flywheel will alow
a much smaller than normal motor to do the job.

Ok, but that's not the way motors are rated or HP is calculated.

...
which are you dissagreeing with?

Motor ratings include the energy from the flywheel.

Horsepower is measured as foot/lbs per second - RPM X Ft Lbs
Torque/5252 is horsepower. Period.

Ok, 550 ft*lbs/sec. I said that earlier.

And a heavy flywheel will allow a small motor to provide significantly
inproved torque for cyclic loads - making, is some cases, a 1/4 horse
motor do the job a 3 horse motor could not do without a flywheel.
Scaled up that's how punch presses work.

The motor will still be rated 1/4hp. That's its average output.

One electric HP is 745 watts, more or less - but to produce that 1 HP
with a motor of 80% efficiency requires 931 watts. And 80% isn't bad
for a "consumer equipment" motor.

80% is very optimistic.

And a series wound motor rated at, say 1 HP constant, may be able to
produce upwards of 4HP or more for periods of up to several minutes,
depending on it's thermal mass, and for duty cycles of up to say 15
or 20%. So that motor, rated at continuous service, is a 1HP motor,
and at cyclic service, perhaps legitimately 4 HP.

....but it's *not* a 4HP motor.

That said - if it is a 115 volt motor, running on a 15 amp circuit, it
is NOT more than a 2 HP motor - definitely - and more likely not more
than 1.5 if starting under no load or with a slow-trip breaker.

It's not even that. 1.5HP on a 20A circuit is believable.

Generally not more than 1 HP if it starts a load on a standard trip
breaker or fuse.

Ok, your point is?

Quite probably. It has been a long time since I have looked that one up, I
knew it was close and I just copied what the doorknob posted. The point was
motors are not 100% efficient and do not run at unity pf.

It was a useless attempt for the trolls. I was suckered, for a time.



"Stuart" wrote in message
...
Curious! When I was at school I was taught that 1hp=746w



In article ,
Josepi wrote:
A one HP motor make use of 748 Watts, not consumes.





--- news://freenews.netfront.net/ - complaints: ---

On Wed, 02 Jun 2010 22:50:43 -0500, "
wrote:

On Wed, 02 Jun 2010 21:26:25 -0400, wrote:

On Tue, 01 Jun 2010 22:06:49 -0500, "
wrote:

On Tue, 01 Jun 2010 22:11:40 -0400, wrote:

On Tue, 01 Jun 2010 20:36:38 -0500, "
wrote:

On Tue, 1 Jun 2010 14:25:33 -0400, "Josepi" wrote:

Quite a few technical electrical errors there but you concept is almost
correct.
A one HP motor make use of 748 Watts, not consumes.

Nope. A 1-HP motor *delivers* one horsepower of mechanical power
(550ft lbs/second). Only a 100% efficient motor would require only 748W (BTW,
"watts" is not capitalized).

120v X 10A = 1200va not watts
Many 1/4HP furnace motors take about 10A at 120volts. How do you figure that
one?

I don't believe you. A 1HP motor may require 1200W at full load, but not a
1/4HP motor.

It can draw 1200 watts at startup. Not terribly uncommon. When
rotating, a whole lot less.

Agreed.

The new 5HP motors are including the inertia of the rotor and do not specify
"how long" they can deliver that HP.

Nope. Well, maybe Crapsman's HP rating. ;-)

Foot lbs torque @ rpm- a heavy rotor or flywheel CAN deliver
significant horsepower for a matter of seconds - after it has been
brought up to speed. In SOME applications, a heavy flywheel will alow
a much smaller than normal motor to do the job.

Ok, but that's not the way motors are rated or HP is calculated.

...
which are you dissagreeing with?

Motor ratings include the energy from the flywheel.

Horsepower is measured as foot/lbs per second - RPM X Ft Lbs
Torque/5252 is horsepower. Period.

Ok, 550 ft*lbs/sec. I said that earlier.

And a heavy flywheel will allow a small motor to provide significantly
inproved torque for cyclic loads - making, is some cases, a 1/4 horse
motor do the job a 3 horse motor could not do without a flywheel.
Scaled up that's how punch presses work.

The motor will still be rated 1/4hp. That's its average output.

One electric HP is 745 watts, more or less - but to produce that 1 HP
with a motor of 80% efficiency requires 931 watts. And 80% isn't bad
for a "consumer equipment" motor.

80% is very optimistic.

And a series wound motor rated at, say 1 HP constant, may be able to
produce upwards of 4HP or more for periods of up to several minutes,
depending on it's thermal mass, and for duty cycles of up to say 15
or 20%. So that motor, rated at continuous service, is a 1HP motor,
and at cyclic service, perhaps legitimately 4 HP.

...but it's *not* a 4HP motor.

That said - if it is a 115 volt motor, running on a 15 amp circuit, it
is NOT more than a 2 HP motor - definitely - and more likely not more
than 1.5 if starting under no load or with a slow-trip breaker.

It's not even that. 1.5HP on a 20A circuit is believable.

Generally not more than 1 HP if it starts a load on a standard trip
breaker or fuse.

Ok, your point is?
What's YOUR point? In yopur last post you said that's not how motors
are rated and horsepower measured. Quote "Ok, but that's not the way
motors are rated or HP is calculated"

I just said it is, and you agreed with me except on the "specialty"
rating of some motors - which ARE rated as I said. A motor CAN have 2
ratings - a constant (average) HP rating and a peak (cyclic or short
duty) rating.

Also, the "real" 2HP Baldor Cap-start cap-run motor I have installed
on my compressor is rated at 20 amps at 115 volts and will start with
the unloader on a 15 amp slow-blow fuse unless it's cold out.
It is only about 65% efficient at full load, Like I said, 80% would
be a pretty good motor (I didn't say 80% was common - I was just
making the point that EVEN WITH an 80% efficient motor,1.5 or 2HP on a
115 volt 15 amp circuit would be MAXIMUM - anyone claiming higher than
that is "more than suspect".

THAT was the point I was making on the LAST post.

Even breakers and fuses take an overload on a time basis.

I have put more than double the current through fuses and they hold for
60-120 seconds. Too many electrical geniuses that have no experience or just
trolls...take your pick...LOL


wrote in message
...
What's YOUR point? In yopur last post you said that's not how motors
are rated and horsepower measured. Quote "Ok, but that's not the way
motors are rated or HP is calculated"

I just said it is, and you agreed with me except on the "specialty"
rating of some motors - which ARE rated as I said. A motor CAN have 2
ratings - a constant (average) HP rating and a peak (cyclic or short
duty) rating.

Also, the "real" 2HP Baldor Cap-start cap-run motor I have installed
on my compressor is rated at 20 amps at 115 volts and will start with
the unloader on a 15 amp slow-blow fuse unless it's cold out.
It is only about 65% efficient at full load, Like I said, 80% would
be a pretty good motor (I didn't say 80% was common - I was just
making the point that EVEN WITH an 80% efficient motor,1.5 or 2HP on a
115 volt 15 amp circuit would be MAXIMUM - anyone claiming higher than
that is "more than suspect".

THAT was the point I was making on the LAST post.



--- news://freenews.netfront.net/ - complaints: ---

Fuses are rated in times it takes to blow.
Slo-blow are just one.

Some are super fast. Those are normally in the micro-to-milli amp specs.

Circuit breakers are the same - some are rated for special loads.
An oven is a nice resistive load. An air conditioner is highly inductive.
Starting load on some motors require longer high current time. Naturally,
if a start winding cap is bad, more current is needed in the run winding...

Martin

Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
"Our Republic and the Press will Rise or Fall Together": Joseph Pulitzer
TSRA: Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Charter Founder
IHMSA and NRA Metallic Silhouette maker & member. http://lufkinced.com/

On 6/3/2010 11:34 PM, Josepi wrote:
Even breakers and fuses take an overload on a time basis.

I have put more than double the current through fuses and they hold for
60-120 seconds. Too many electrical geniuses that have no experience or just
trolls...take your pick...LOL


wrote in message
...
What's YOUR point? In yopur last post you said that's not how motors
are rated and horsepower measured. Quote "Ok, but that's not the way
motors are rated or HP is calculated"

I just said it is, and you agreed with me except on the "specialty"
rating of some motors - which ARE rated as I said. A motor CAN have 2
ratings - a constant (average) HP rating and a peak (cyclic or short
duty) rating.

Also, the "real" 2HP Baldor Cap-start cap-run motor I have installed
on my compressor is rated at 20 amps at 115 volts and will start with
the unloader on a 15 amp slow-blow fuse unless it's cold out.
It is only about 65% efficient at full load, Like I said, 80% would
be a pretty good motor (I didn't say 80% was common - I was just
making the point that EVEN WITH an 80% efficient motor,1.5 or 2HP on a
115 volt 15 amp circuit would be MAXIMUM - anyone claiming higher than
that is "more than suspect".

THAT was the point I was making on the LAST post.



--- news://freenews.netfront.net/ - complaints: ---

Here are some Hubbel fuse curves.

http://www.hubbellpowersystems.com/s...rves/30003.jpg

Notice how even the "fast blow" type K types do not clear the circuit under
twice (two times for the Americans = 2x) their rated current level, even
after 5 minutes.

Type K are the fast blow types usually found in better Fluke digital meters
and other sensitive instruments. Other fuses are typically slower than this.

Breakers vary a lot over the years and manufacturer, Most of the cheap panel
ones were thermal and take a lot to trip them out the first time. Then the
rating is not guaranteed and need to be replaced. (read the fine print)
Nobody ever does.

Here is a curve for the thermal magnetic combo units referred to by Lew.
Notice the time curve for long slow overloads starts at 100% as well as the
instantaneous levels at about 800%. Much better protection for you table saw
and other equipment motors.

http://www.sea.siemens.com/us/intern...70A_1-Pole.pdf




"Lew Hodgett" wrote in message
...
Molded case c'bkrs are thermal-magnetic devices.

The magnetic portion monitors the inrush characteristics of the load
which will cause the c'bkr to trip instantaneously if the inrush
current exceeds rating.

OTOH the thermal portion of the device monitors the thermal
characteristics on an inverse time basis.

(The larger the overload, the quicker the c'bkr trips)

There is also a special purpose molded case device known as a "Mag
only" or "motor protector".

These devices are used in 3 phase combination motor starter units and
would have no application in the typical single phase home shop
installation.

Lew




--- news://freenews.netfront.net/ - complaints: ---