I have a home workshop and needed 220 V circuits for certain power tools
and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.

The 220V 50A circuit for the AC happened to terminate on one wall of the
shop. So, taking advantage of the situation, I decided to set up a
subpanel using the former AC circuit. I am not an electrician, but have
done other electrical work around the house, including wiring attic
fans, adding new outdoor circuits, etc.

I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the dust
collector, and connected to the neutral bar was charred for about two
inches from the bus. Most of the insulation had been burned off along
those two inches. Also, the black plastic around the neutral bus shows
signs of having melted around the perimeter of the neutral bus bar.

The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.

I checked the screw which held the charred wire to the neutral bus bar
and it was tight I also checked the screw holding the neutral wire for
the other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is rated
for both Al and Cu wire.

Does anyone have any ideas as to what the problem could be?

Thanks,
CW

I don't have an answer for you, just some questions...

1) Did you wire the subpanel correctly, with separated neutral and ground
buses?
2) The charring was away from the aluminum wire, right?

toller wrote:
I don't have an answer for you, just some questions...

1) Did you wire the subpanel correctly, with separated neutral and ground
buses?
2) The charring was away from the aluminum wire, right?



Yes, the neutrals are all connected to the neutral bus and the grounds
are connected to a separate ground bus on the opposite side of the box.

The 50A Al feed Neutral from the main box is connected by the large
screw to the top of the Neutral bus. It has no damage, nor do the other
Al wires.

The 220V circuit for the saws had been operating from the subpanel for
months before the two 120V circuits were added. The two 120V circuits
operated without any damage for at least a week or more after they were
installed. I know that because I had been removing the front panel
periodically assessing options for additional circuits for some time
after those 120V circuits were added.

I do not know when the damage occurred after that time. But, I do know
that the dust collector has operated and can still operate fine from
that damaged circuit Of course, at this point,I have secured power to
the entire subpanel until I can determine what caused the problem.

Thanks,
CW

In article dXpWd.84446$JZ2.14012@fed1read02, Seawulf wrote:
I have a home workshop and needed 220 V circuits for certain power tools
and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.

You may find that to be a problem when you try to sell the house. Separate
issue, I know, but something you should keep in mind.

The 220V 50A circuit for the AC happened to terminate on one wall of the
shop. So, taking advantage of the situation, I decided to set up a
subpanel using the former AC circuit. I am not an electrician, but have
done other electrical work around the house, including wiring attic
fans, adding new outdoor circuits, etc.

Does that circuit have both a neutral and a ground? If not, it's *not*
suitable for feeding a subpanel, and must be replaced.

I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.

That dust collector circuit is a potential problem. Depending on how long you
use it at a time, it may meet the Code definition of a continuous load and
thus require that the ampacity of the circuit be derated 20% to 16A. This
should have been wired with 10ga wire, which can carry up to 24A of continuous
load current.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the dust
collector, and connected to the neutral bar was charred for about two
inches from the bus. Most of the insulation had been burned off along
those two inches. Also, the black plastic around the neutral bus shows
signs of having melted around the perimeter of the neutral bus bar.

Wow.

No damage to the neutral conductors for the other circuits, right? Then
there's something amiss with that circuit, or with what's plugged into it.

I think you oughta have a look at that dust collector motor. You said (above)
that it's a dual-voltage motor. I wonder if the jumpers are set for 240V
instead of 120V.

The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.

That doesn't mean that it will trip at the proper current draw, though.

I checked the screw which held the charred wire to the neutral bus bar
and it was tight I also checked the screw holding the neutral wire for
the other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is rated
for both Al and Cu wire.

I hope the wire in that cable is at least 6ga minimum if the conductor
temperature rating is 75 deg C or higher, or 4ga minimum for 60 C conductors.

Does anyone have any ideas as to what the problem could be?

Check the jumpers on the dust collector motor and make sure they're set for
120V operation.

Also check to make sure there's adequate air flow for the dust collector. If
it's having to work too hard to draw air through too-small piping, it will
draw more current too.

Redo that circuit with 10ga wire. And replace the receptacle: it's probably
damaged too.

Check the connections on the cable that feeds that subpanel, at *both* ends
of all four conductors. (You *do* have four, don't you, two hots, neutral, and
ground?) If the neutral isn't tied down tight at both ends, you may be getting
a higher voltage in one leg of the subpanel than the other. Won't make any
difference to your 240V tools, but it plays hell with 120V devices. You might
have been pumping 150V or so through the dust collector.

If the circuit feeding your subpanel has only three conductors, replace it
with the proper cable. Might as well switch to copper while you're at it. For
50A, you need 8/3 with ground (conductor temp rating 75 deg C or higher), or
6/3 with ground (conductor temp rating 60 deg C).

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

Generally a situation like that occurs when the connection is loose. It
simply heats at the location of the bad connection. Try stripping the burned
connections off and reconnecting them, use the equipment for a short while
then feel the wires and see if they have gotten hot. Some antiox paste
wouldn't hurt either
"Seawulf" wrote in message
news:jNrWd.87574$JZ2.82457@fed1read02...

toller wrote:
I don't have an answer for you, just some questions...

1) Did you wire the subpanel correctly, with separated neutral and ground
buses?
2) The charring was away from the aluminum wire, right?

Yes, the neutrals are all connected to the neutral bus and the grounds are
connected to a separate ground bus on the opposite side of the box.

The 50A Al feed Neutral from the main box is connected by the large
screw to the top of the Neutral bus. It has no damage, nor do the other
Al wires.

The 220V circuit for the saws had been operating from the subpanel for
months before the two 120V circuits were added. The two 120V circuits
operated without any damage for at least a week or more after they were
installed. I know that because I had been removing the front panel
periodically assessing options for additional circuits for some time after
those 120V circuits were added.

I do not know when the damage occurred after that time. But, I do know
that the dust collector has operated and can still operate fine from that
damaged circuit Of course, at this point,I have secured power to the
entire subpanel until I can determine what caused the problem.

Thanks,
CW

To create heat necessary to burn insulation, one of two
problems must occur. Either too much current is being carried
on that wire (which is not likely) or a connection at the
point of burning is loose - causing a voltage drop at that
connection so high as to create heat. If the latter is true,
then what you though was a motor working just fine was
actually a motor under undue stress due to insufficient
voltage. IOW we have an example of a conclusion not based
upon the numbers.

Had you monitored that wall receptacle voltage when under
load, the problem would have been apparent then. The reason
we usually don't is that such failures are rare. But this is
the point. What you observed to be a fully functional system
was instead a system with one minor defect. Well such is life
and why being a human is so interesting.

If you don't find a loose screw at the point of burning
insulation, then we may have a much more serious problem. The
question that must be answered - why so much heat on that
wire? Maybe a trivial problem (ie loose screw) or maybe
symptoms of a human safety problem. Other posters have
provided useful background facts.

Seawulf wrote:
toller wrote:
I don't have an answer for you, just some questions...

1) Did you wire the subpanel correctly, with separated neutral
and ground buses?
2) The charring was away from the aluminum wire, right?

Yes, the neutrals are all connected to the neutral bus and the grounds
are connected to a separate ground bus on the opposite side of the box.

The 50A Al feed Neutral from the main box is connected by the large
screw to the top of the Neutral bus. It has no damage, nor do the other
Al wires.

The 220V circuit for the saws had been operating from the subpanel for
months before the two 120V circuits were added. The two 120V circuits
operated without any damage for at least a week or more after they were
installed. I know that because I had been removing the front panel
periodically assessing options for additional circuits for some time
after those 120V circuits were added.

I do not know when the damage occurred after that time. But, I do know
that the dust collector has operated and can still operate fine from
that damaged circuit Of course, at this point,I have secured power to
the entire subpanel until I can determine what caused the problem.

Thanks,
CW

CW,
Back when I was small we had a similar problem with our main house
panel. My father and I smelled burning plastic when we wee in the
basement. He removed the front panel and we saw the plastic holding the
2 "phases" had melted.
Turns out we were just running too much continuos power through the
panel and had to upgrade.
We had an electrician replace the panel and upgrade the service.
Michelle

Seawulf wrote:

I have a home workshop and needed 220 V circuits for certain power
tools and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.

The 220V 50A circuit for the AC happened to terminate on one wall of
the shop. So, taking advantage of the situation, I decided to set up
a subpanel using the former AC circuit. I am not an electrician, but
have done other electrical work around the house, including wiring
attic fans, adding new outdoor circuits, etc.

I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the
dust collector, and connected to the neutral bar was charred for about
two inches from the bus. Most of the insulation had been burned off
along those two inches. Also, the black plastic around the neutral bus
shows signs of having melted around the perimeter of the neutral bus bar.

The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.

I checked the screw which held the charred wire to the neutral bus bar
and it was tight I also checked the screw holding the neutral wire
for the other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is
rated for both Al and Cu wire.

Does anyone have any ideas as to what the problem could be?

Thanks,
CW

"Michelle P" wrote in message
ink.net...
CW,
Back when I was small we had a similar problem with our main house panel.
My father and I smelled burning plastic when we wee in the basement. He
removed the front panel and we saw the plastic holding the 2 "phases" had
melted.
Turns out we were just running too much continuos power through the panel
and had to upgrade.
We had an electrician replace the panel and upgrade the service.


Assuming you had a main breaker, it should have tripped to prevent that.
That can't be his problem, since he has only 40a maximum out of the
subpanel.

The 220V 50A circuit for the AC happened to terminate on one wall of the
shop. So, taking advantage of the situation, I decided to set up a
subpanel using the former AC circuit.

Did you pull a neutral from the sub to the main panel?

"Doug Miller" wrote in message
. ..

Also check to make sure there's adequate air flow for the dust collector.
If
it's having to work too hard to draw air through too-small piping, it will
draw more current too.



WRONG. If there is a restriction, the dust collector motor will draw LESS
current because it is moving less air.






--
Regards,
Doug Miller (alphageek at milmac dot com)

Lots of good advice in other's posts. Another remote possibility is that the
damage was caused by arcing induced from a lightning strike surge. Otherwise
such damage is nearly always caused by a loose and/or dirty connection.
Damage over a short part of the wire would be very unlikely to have been
from excessive current.
Don Young
"Seawulf" wrote in message
news:dXpWd.84446$JZ2.14012@fed1read02...
I have a home workshop and needed 220 V circuits for certain power tools
and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and died.
We live in southern California and do not have many really hot days, so we
decided to not repair it again and just let it be.

The 220V 50A circuit for the AC happened to terminate on one wall of the
shop. So, taking advantage of the situation, I decided to set up a
subpanel using the former AC circuit. I am not an electrician, but have
done other electrical work around the house, including wiring attic fans,
adding new outdoor circuits, etc.

I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check something
and found that the neutral wire for the line feeding the dust collector,
and connected to the neutral bar was charred for about two inches from the
bus. Most of the insulation had been burned off along those two inches.
Also, the black plastic around the neutral bus shows signs of having
melted around the perimeter of the neutral bus bar.

The circuit breaker on the dust collector line was still engaged. I also
tested the cb and found that it does shut off power to the circuit.

I checked the screw which held the charred wire to the neutral bus bar and
it was tight I also checked the screw holding the neutral wire for the
other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is rated
for both Al and Cu wire.

Does anyone have any ideas as to what the problem could be?

Thanks,
CW

I'm guessing that the 12-2 romex is too small for the 18 amp load. The
nameplate reads 120volt/18amps but in reality it's possible that your
voltage is only 110 or 115 with a load on. In that case your motor will
draw more than 18 amps. The neutral connection may have also been a little
loose to cause the charring.

The dust collector should have been wired with a 30 amp circuit or changed
to operate at 220 volts.


"Seawulf" wrote in message
news:dXpWd.84446$JZ2.14012@fed1read02...
I have a home workshop and needed 220 V circuits for certain power tools
and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.

The 220V 50A circuit for the AC happened to terminate on one wall of the
shop. So, taking advantage of the situation, I decided to set up a
subpanel using the former AC circuit. I am not an electrician, but have
done other electrical work around the house, including wiring attic
fans, adding new outdoor circuits, etc.

I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the dust
collector, and connected to the neutral bar was charred for about two
inches from the bus. Most of the insulation had been burned off along
those two inches. Also, the black plastic around the neutral bus shows
signs of having melted around the perimeter of the neutral bus bar.

The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.

I checked the screw which held the charred wire to the neutral bus bar
and it was tight I also checked the screw holding the neutral wire for
the other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is rated
for both Al and Cu wire.

Does anyone have any ideas as to what the problem could be?

Thanks,
CW

"Seawulf" wrote in message
news:jNrWd.87574$JZ2.82457@fed1read02...

toller wrote:
I don't have an answer for you, just some questions...

1) Did you wire the subpanel correctly, with separated neutral and
ground
buses?
2) The charring was away from the aluminum wire, right?



Yes, the neutrals are all connected to the neutral bus and the grounds
are connected to a separate ground bus on the opposite side of the box.


Very interesting. I have NEVER seen an A/C compressor with a 4 wire cable.

Sounds more like your using the ground as a neutral.

Works yes, good practice not even close

SQLit wrote:
"Seawulf" wrote in message
news:jNrWd.87574$JZ2.82457@fed1read02...

toller wrote:

I don't have an answer for you, just some questions...

1) Did you wire the subpanel correctly, with separated neutral and

ground

buses?
2) The charring was away from the aluminum wire, right?



Yes, the neutrals are all connected to the neutral bus and the grounds
are connected to a separate ground bus on the opposite side of the box.



Very interesting. I have NEVER seen an A/C compressor with a 4 wire cable.

Sounds more like your using the ground as a neutral.

Works yes, good practice not even close



I didn't I switched the two. The totally bare - no insulation - wire is
connected to the ground bus and the insulated - white - wire is
connected to the Neutral bus. IOW, hard to get them mixed up.
Thanks,
CDW

toller wrote:
"Michelle P" wrote in message
ink.net...

CW,
Back when I was small we had a similar problem with our main house panel.
My father and I smelled burning plastic when we wee in the basement. He
removed the front panel and we saw the plastic holding the 2 "phases" had
melted.
Turns out we were just running too much continuos power through the panel
and had to upgrade.
We had an electrician replace the panel and upgrade the service.



Assuming you had a main breaker, it should have tripped to prevent that.
That can't be his problem, since he has only 40a maximum out of the
subpanel.


The 50A 220 breaker for the subpanel is on the main panel. Niether it
or the individual breakers on the subpanel tripped.
Thanks,
CDW

Doug Miller wrote:
In article dXpWd.84446$JZ2.14012@fed1read02, Seawulf wrote:

I have a home workshop and needed 220 V circuits for certain power tools
and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.


You may find that to be a problem when you try to sell the house. Separate
issue, I know, but something you should keep in mind.

The 220V 50A circuit for the AC happened to terminate on one wall of the
shop. So, taking advantage of the situation, I decided to set up a
subpanel using the former AC circuit. I am not an electrician, but have
done other electrical work around the house, including wiring attic
fans, adding new outdoor circuits, etc.


Does that circuit have both a neutral and a ground? If not, it's *not*
suitable for feeding a subpanel, and must be replaced.


I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.


That dust collector circuit is a potential problem. Depending on how long you
use it at a time, it may meet the Code definition of a continuous load and
thus require that the ampacity of the circuit be derated 20% to 16A. This
should have been wired with 10ga wire, which can carry up to 24A of continuous
load current.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the dust
collector, and connected to the neutral bar was charred for about two
inches from the bus. Most of the insulation had been burned off along
those two inches. Also, the black plastic around the neutral bus shows
signs of having melted around the perimeter of the neutral bus bar.


Wow.

No damage to the neutral conductors for the other circuits, right? Then
there's something amiss with that circuit, or with what's plugged into it.

I think you oughta have a look at that dust collector motor. You said (above)
that it's a dual-voltage motor. I wonder if the jumpers are set for 240V
instead of 120V.

The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.


That doesn't mean that it will trip at the proper current draw, though.

I checked the screw which held the charred wire to the neutral bus bar
and it was tight I also checked the screw holding the neutral wire for
the other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is rated
for both Al and Cu wire.


I hope the wire in that cable is at least 6ga minimum if the conductor
temperature rating is 75 deg C or higher, or 4ga minimum for 60 C conductors.

Does anyone have any ideas as to what the problem could be?


Check the jumpers on the dust collector motor and make sure they're set for
120V operation.

It is labled as 120 and I checked the actual wiring agains the 120V and
220V diagrams for the unit and it is definitely wired for 120V.

Also check to make sure there's adequate air flow for the dust collector. If
it's having to work too hard to draw air through too-small piping, it will
draw more current too.

Redo that circuit with 10ga wire. And replace the receptacle: it's probably
damaged too.

Check the connections on the cable that feeds that subpanel, at *both* ends
of all four conductors. (You *do* have four, don't you, two hots, neutral, and
ground?) If the neutral isn't tied down tight at both ends, you may be getting
a higher voltage in one leg of the subpanel than the other. Won't make any
difference to your 240V tools, but it plays hell with 120V devices. You might
have been pumping 150V or so through the dust collector.

Tje Neutral was tight at both the Main and Subpanel.

If the circuit feeding your subpanel has only three conductors, replace it
with the proper cable. Might as well switch to copper while you're at it. For
50A, you need 8/3 with ground (conductor temp rating 75 deg C or higher), or
6/3 with ground (conductor temp rating 60 deg C).

Yes, the 5A 220 feed from the main panel has two black, a white and a
ground wire. It is difficult to read the label on the sheathing - red
text on grey sheath. It is either 6 or 8 gauge and I can't really make
out much more of the ratings on the part of the cable that is exposed.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?

Thanks for your comments,
CDW

Seawulf wrote:
Doug Miller wrote:

In article dXpWd.84446$JZ2.14012@fed1read02, Seawulf
wrote:

I have a home workshop and needed 220 V circuits for certain power
tools and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.



You may find that to be a problem when you try to sell the house.
Separate issue, I know, but something you should keep in mind.

The 220V 50A circuit for the AC happened to terminate on one wall of
the shop. So, taking advantage of the situation, I decided to set up
a subpanel using the former AC circuit. I am not an electrician, but
have done other electrical work around the house, including wiring
attic fans, adding new outdoor circuits, etc.



Does that circuit have both a neutral and a ground? If not, it's *not*
suitable for feeding a subpanel, and must be replaced.


I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for
new receptacles. The saws are each rated at 220V/13A and are never
run concurrently, One of the 120V receptacles was dedicated to a
dust collector rated at 120V/18A or 220V 9A.



That dust collector circuit is a potential problem. Depending on how
long you use it at a time, it may meet the Code definition of a
continuous load and thus require that the ampacity of the circuit be
derated 20% to 16A. This should have been wired with 10ga wire, which
can carry up to 24A of continuous load current.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the
dust collector, and connected to the neutral bar was charred for
about two inches from the bus. Most of the insulation had been
burned off along those two inches. Also, the black plastic around the
neutral bus shows signs of having melted around the perimeter of the
neutral bus bar.



Wow.

No damage to the neutral conductors for the other circuits, right?
Then there's something amiss with that circuit, or with what's plugged
into it.

I think you oughta have a look at that dust collector motor. You said
(above) that it's a dual-voltage motor. I wonder if the jumpers are
set for 240V instead of 120V.

The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.



That doesn't mean that it will trip at the proper current draw, though.

I checked the screw which held the charred wire to the neutral bus
bar and it was tight I also checked the screw holding the neutral
wire for the other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is
rated for both Al and Cu wire.



I hope the wire in that cable is at least 6ga minimum if the conductor
temperature rating is 75 deg C or higher, or 4ga minimum for 60 C
conductors.

Does anyone have any ideas as to what the problem could be?



Check the jumpers on the dust collector motor and make sure they're
set for 120V operation.

It is labled as 120 and I checked the actual wiring agains the 120V and
220V diagrams for the unit and it is definitely wired for 120V.

Also check to make sure there's adequate air flow for the dust
collector. If it's having to work too hard to draw air through
too-small piping, it will draw more current too.

Redo that circuit with 10ga wire. And replace the receptacle: it's
probably damaged too.

Check the connections on the cable that feeds that subpanel, at *both*
ends of all four conductors. (You *do* have four, don't you, two hots,
neutral, and ground?) If the neutral isn't tied down tight at both
ends, you may be getting a higher voltage in one leg of the subpanel
than the other. Won't make any difference to your 240V tools, but it
plays hell with 120V devices. You might have been pumping 150V or so
through the dust collector.


Tje Neutral was tight at both the Main and Subpanel.

If the circuit feeding your subpanel has only three conductors,
replace it with the proper cable. Might as well switch to copper while
you're at it. For 50A, you need 8/3 with ground (conductor temp rating
75 deg C or higher), or 6/3 with ground (conductor temp rating 60 deg C).

Yes, the 5A 220 feed from the main panel has two black, a white and a
ground wire. It is difficult to read the label on the sheathing - red
text on grey sheath. It is either 6 or 8 gauge and I can't really make
out much more of the ratings on the part of the cable that is exposed.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?


Thanks for your comments,
CDW

Sorry for the typo - The 220 feed from the Main panel is, of course,
50A, not 5A.
CDW

John Grabowski wrote:
I'm guessing that the 12-2 romex is too small for the 18 amp load. The
nameplate reads 120volt/18amps but in reality it's possible that your
voltage is only 110 or 115 with a load on. In that case your motor will
draw more than 18 amps. The neutral connection may have also been a little
loose to cause the charring.

The dust collector should have been wired with a 30 amp circuit or changed
to operate at 220 volts.

I get your point. But, if the charring of the insulation on the
respective Neutral wire was due to an over-Amperage, (i.e. enough to
create sufficient heat for sufficient time)I would expect the breaker to
trip. Of course, that assumes the breaker actually trips IAW spec -
which I do NOT know to be the case.

Someone else suggested that a more-or-less continuous operation of the
dust collector, would, itself, require a de-rating of the cable
amperage load spec and, as you suggest, moving to a 10 gauge cable.
But, in fact, the dust collector runs very intermittently. I usually
have it connected to my small 13 inch thickness planer, which is rarely
run for more than 5 continuous minutes less than an average of twice a
week. Otherwise, I use it periodically to clean out the bandsaw and
table saw accumulations.

Thanks for you help,
CDW


"Seawulf" wrote in message
news:dXpWd.84446$JZ2.14012@fed1read02...

I have a home workshop and needed 220 V circuits for certain power tools
and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.

The 220V 50A circuit for the AC happened to terminate on one wall of the
shop. So, taking advantage of the situation, I decided to set up a
subpanel using the former AC circuit. I am not an electrician, but have
done other electrical work around the house, including wiring attic
fans, adding new outdoor circuits, etc.

I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the dust
collector, and connected to the neutral bar was charred for about two
inches from the bus. Most of the insulation had been burned off along
those two inches. Also, the black plastic around the neutral bus shows
signs of having melted around the perimeter of the neutral bus bar.

The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.

I checked the screw which held the charred wire to the neutral bus bar
and it was tight I also checked the screw holding the neutral wire for
the other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is rated
for both Al and Cu wire.

Does anyone have any ideas as to what the problem could be?

Thanks,
CW

Seawulf wrote:
John Grabowski wrote:

I'm guessing that the 12-2 romex is too small for the 18 amp load. The
nameplate reads 120volt/18amps but in reality it's possible that your
voltage is only 110 or 115 with a load on. In that case your motor will
draw more than 18 amps. The neutral connection may have also been a
little
loose to cause the charring.

The dust collector should have been wired with a 30 amp circuit or
changed
to operate at 220 volts.

I get your point. But, if the charring of the insulation on the
respective Neutral wire was due to an over-Amperage, (i.e. enough to
create sufficient heat for sufficient time)I would expect the breaker to
trip. Of course, that assumes the breaker actually trips IAW spec -
which I do NOT know to be the case.

Someone else suggested that a more-or-less continuous operation of the
dust collector, would, itself, require a de-rating of the cable
amperage load spec and, as you suggest, moving to a 10 gauge cable. But,
in fact, the dust collector runs very intermittently. I usually have it
connected to my small 13 inch thickness planer, which is rarely run for
more than 5 continuous minutes less than an average of twice a week.
Otherwise, I use it periodically to clean out the bandsaw and table saw
accumulations.



I wonder if that white wire was nicked or had some broken strands? You
were operating it near its maximum rating, and it might have had a bad
spot that overheated.

In any case, I would probably rewire the blower motor for 240V and put
it on a 2-pole breaker. If you don't have a space for it*, either
double it up with the bandsaw, or tie the handles together on those 20A
single breakers (use the breaker manufacturer's handle ties, or else
pull the single breakers out and replace with a proper 2-pole breaker)
and run the dust collector on 240V onthe same circuit as your 120V
stuff. (not sure if this meets code requirements or not, but it's close)

*From your earlier description, I assume you have a little 100A panel
with 6 spaces, and it's already full with two 2-pole breakers and two
single 20A breakers.

Bob

I am also puzzled by the neutral conductor burning, but not the hot
conductor. Assuming the neutral had a tight connection it indicates to me
that the neutral was carrying more current than the hot. This would only be
possible if the neutral conductor is shared by another circuit which is also
on the same phase as the dust collector. Is it possible that your planer is
on the same phase as the dust collector and their respective receptacles
share a common neutral?


"Seawulf" wrote in message
news:5xIWd.113248$JZ2.87587@fed1read02...
John Grabowski wrote:
I'm guessing that the 12-2 romex is too small for the 18 amp load. The
nameplate reads 120volt/18amps but in reality it's possible that your
voltage is only 110 or 115 with a load on. In that case your motor will
draw more than 18 amps. The neutral connection may have also been a
little
loose to cause the charring.

The dust collector should have been wired with a 30 amp circuit or
changed
to operate at 220 volts.

I get your point. But, if the charring of the insulation on the
respective Neutral wire was due to an over-Amperage, (i.e. enough to
create sufficient heat for sufficient time)I would expect the breaker to
trip. Of course, that assumes the breaker actually trips IAW spec -
which I do NOT know to be the case.

Someone else suggested that a more-or-less continuous operation of the
dust collector, would, itself, require a de-rating of the cable
amperage load spec and, as you suggest, moving to a 10 gauge cable.
But, in fact, the dust collector runs very intermittently. I usually
have it connected to my small 13 inch thickness planer, which is rarely
run for more than 5 continuous minutes less than an average of twice a
week. Otherwise, I use it periodically to clean out the bandsaw and
table saw accumulations.

Thanks for you help,
CDW


"Seawulf" wrote in message
news:dXpWd.84446$JZ2.14012@fed1read02...

I have a home workshop and needed 220 V circuits for certain power tools
and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.

The 220V 50A circuit for the AC happened to terminate on one wall of the
shop. So, taking advantage of the situation, I decided to set up a
subpanel using the former AC circuit. I am not an electrician, but have
done other electrical work around the house, including wiring attic
fans, adding new outdoor circuits, etc.

I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the dust
collector, and connected to the neutral bar was charred for about two
inches from the bus. Most of the insulation had been burned off along
those two inches. Also, the black plastic around the neutral bus shows
signs of having melted around the perimeter of the neutral bus bar.

The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.

I checked the screw which held the charred wire to the neutral bus bar
and it was tight I also checked the screw holding the neutral wire for
the other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is rated
for both Al and Cu wire.

Does anyone have any ideas as to what the problem could be?

Thanks,
CW

The Neutral had a tight connection, as did the other circuit Neutral and
the 50A Al feed Neutral.

The dust collector has a dedicated line because of my concern about its
18A pull on the 20A breaker. The planer is on the remaining 120V
circuit from the subpanel, the Neutral wire of which shows no damage.

Your rationale about the apparent unbalanced current draw on the Hot and
Neutral lines seems well founded. However, it also assumes that the
underlying problem was with that circuit.

Based on my own subsequent analysis and that of others on the
rec.woodworking group, I now believe that the underlying problem was the
connection of the Al 50A feed Neutral to the bus bar. I now believe
that the connector problem - well known with Al wire - caused the bus
bar to overheat (remember, the plastic around the bar shows signs of
melting) and that caused the insulation on the dust collector neutral
wire to char - because - I now assume - the insulation was probably in
contact with the neutral bus bar. Neither the feed Al line or the other
120V neutral line have their insulation within 1/4 inch of the bar.
This is conjecture at this point, but does seem to address all of the
observations and known facts.

CDW

John Grabowski wrote:
I am also puzzled by the neutral conductor burning, but not the hot
conductor. Assuming the neutral had a tight connection it indicates to me
that the neutral was carrying more current than the hot. This would only be
possible if the neutral conductor is shared by another circuit which is also
on the same phase as the dust collector. Is it possible that your planer is
on the same phase as the dust collector and their respective receptacles
share a common neutral?


"Seawulf" wrote in message
news:5xIWd.113248$JZ2.87587@fed1read02...

John Grabowski wrote:

I'm guessing that the 12-2 romex is too small for the 18 amp load. The
nameplate reads 120volt/18amps but in reality it's possible that your
voltage is only 110 or 115 with a load on. In that case your motor will
draw more than 18 amps. The neutral connection may have also been a

little

loose to cause the charring.

The dust collector should have been wired with a 30 amp circuit or

changed

to operate at 220 volts.


I get your point. But, if the charring of the insulation on the
respective Neutral wire was due to an over-Amperage, (i.e. enough to
create sufficient heat for sufficient time)I would expect the breaker to
trip. Of course, that assumes the breaker actually trips IAW spec -
which I do NOT know to be the case.

Someone else suggested that a more-or-less continuous operation of the
dust collector, would, itself, require a de-rating of the cable
amperage load spec and, as you suggest, moving to a 10 gauge cable.
But, in fact, the dust collector runs very intermittently. I usually
have it connected to my small 13 inch thickness planer, which is rarely
run for more than 5 continuous minutes less than an average of twice a
week. Otherwise, I use it periodically to clean out the bandsaw and
table saw accumulations.

Thanks for you help,
CDW


"Seawulf" wrote in message
news:dXpWd.84446$JZ2.14012@fed1read02...


I have a home workshop and needed 220 V circuits for certain power tools
and 120 V circuits for lighting and receptacles.

Around the same time our central air conditioning system faded and
died. We live in southern California and do not have many really hot
days, so we decided to not repair it again and just let it be.

The 220V 50A circuit for the AC happened to terminate on one wall of the
shop. So, taking advantage of the situation, I decided to set up a
subpanel using the former AC circuit. I am not an electrician, but have
done other electrical work around the house, including wiring attic
fans, adding new outdoor circuits, etc.

I added the subpanel and ran a 220/20A line (10-2G NM-B cable) to the
tablesaw and bandsaw and two 120/20 A lines (12-2G NM-B cable) for new
receptacles. The saws are each rated at 220V/13A and are never run
concurrently, One of the 120V receptacles was dedicated to a dust
collector rated at 120V/18A or 220V 9A.

I have been running this setup for about two years with no apparent
problems. I recently removed the cover on the subpanel to check
something and found that the neutral wire for the line feeding the dust
collector, and connected to the neutral bar was charred for about two
inches from the bus. Most of the insulation had been burned off along
those two inches. Also, the black plastic around the neutral bus shows
signs of having melted around the perimeter of the neutral bus bar.

The circuit breaker on the dust collector line was still engaged. I
also tested the cb and found that it does shut off power to the circuit.

I checked the screw which held the charred wire to the neutral bus bar
and it was tight I also checked the screw holding the neutral wire for
the other 120V line, and it was also tight.

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is rated
for both Al and Cu wire.

Does anyone have any ideas as to what the problem could be?

Thanks,
CW

I am also puzzled by the neutral conductor burning, but not the hot
conductor. Assuming the neutral had a tight connection it indicates to me
that the neutral was carrying more current than the hot. This would only be
possible if the neutral conductor is shared by another circuit which is also

You didn't move the 50A breaker in the main panel, did you?
If you've somehow got both the hots feeding the subpanel
on the same phase, that would overload the neutral, too, and some
panels allow you to do that. (It would also explain
why the AC unit croaked.)

The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is
rated
for both Al and Cu wire.

you need to tighten all the alum connections , both ends the feed at main
panel and sub panel connections and would be wise to invest in a
simple clamp on amp meter..

Goedjn wrote:
I am also puzzled by the neutral conductor burning, but not the hot
conductor. Assuming the neutral had a tight connection it indicates to me
that the neutral was carrying more current than the hot. This would only be
possible if the neutral conductor is shared by another circuit which is also


You didn't move the 50A breaker in the main panel, did you?

No. Nothing was disturbed on the main panel.

If you've somehow got both the hots feeding the subpanel
on the same phase, that would overload the neutral, too, and some
panels allow you to do that. (It would also explain
why the AC unit croaked.)

My 220V table saw and band saw have both been operating off the panel
for a few years, now. So, that indicated to me the phasing on the panel
is correct.

Thanks for your comments,
CDW

Interestingly, when I tested the connections on the subpanel, although
all of the screws on the Neutral bus were tight, the screws on the two
hot phase wires were not tight. I got at least 1/4 turn on each. They,
along with all others have been re-tightened. But, it looks like I
really need to follow Charley's advice relative the the Al wiring being
cleaned and anti-ox paste used, etc. as well as replacing the subpanel
enclosure.

The amp meter would be used to measure actual amperage on the active
circuits to check for over-amp conditions?

BTW, I did verify the language on the Murray subpanel relative to being
rated for AL and Cu wire. The UL Panelboard Marking Guide stipulates
the phrase "Use Copper or Aluminum Wire" for this situation. The panel
actually reads "Use Cu/AL wire on pannelboard line and neutral
terminals." These two statements seem to be the same to me.

Thanks for your comments,
CDW

bumtracks wrote:
The 50A line from the main box to the workshop subpanel is Aluminum
(house is mid 70's vintage) and the Murray subpanel in the shop is
rated
for both Al and Cu wire.


you need to tighten all the alum connections , both ends the feed at main
panel and sub panel connections and would be wise to invest in a
simple clamp on amp meter..

Run a new copper wire to the outlets. 18 amps is quite a draw, and the
risk of a fire ain't worth going cheap. What would the insurance
adjuster think of your setup? 240 V to the dust collector is actually
safer in this case, i think.
JohnK