Existing situation:
The wiring in the garage dates from the 50s or 60s. There is a breaker box with
a two 15A breakers that feeds the plugs and lights. There is one duplex
receptacle that is wired for 240V - it's hooked up to both hot wires from the
two breakers. The rest of the 120V plugs, etc. come off one of the breakers. The
other breaker is not currently used.

The 240V plug was taped over - I previously didn't even know it was live. I
would like to get access to a 240V circuit. However, I am concerned about the
(existing) apparent mixing of 120 and 240 circuits.

Questions:
1) Is is permissible to run 120V and 240V circuits off the same pair of circuit
breakers - if they are ganged together?
2) If breakers are ganged together, and one leg is overloaded, are they both
supposed to trip? I performed a little test:
a) with the two breakers separate, an overload (120V) visibly trips one breaker
- the handle moves to the off position.
b) with the two breakers ganged together, the same overload internally trips the
same breaker, but the handles don't move, and the other breaker remains live. Is
this proper behavior? Turning the breakers off, the on again resets the tripped
breaker.
3) Do breakers 'wear out' or degrade over time? One reason I want a 240V circuit
is I'm experiencing nuisance tripping when running my table saw under load. Is
it possible that the breaker is just tripping prematurely?
4) Should I just leave the the whole existing mess alone, get an upgraded power
drop, main panel and add 240V circuits? This option is MUCH more expensive...

I was looking for the NEC online, but it looks like I have to buy a copy, or see
if the library has one...

Thanks!
--
JeffB
remove no.spam. to email

i dont know about the rest, but, you CANT run 120 and 240 on the same
circuit. i had the same setup at my house.

"JeffB" wrote in message
...
Existing situation:
The wiring in the garage dates from the 50s or 60s. There is a breaker box
with
a two 15A breakers that feeds the plugs and lights. There is one duplex
receptacle that is wired for 240V - it's hooked up to both hot wires from
the
two breakers. The rest of the 120V plugs, etc. come off one of the
breakers. The
other breaker is not currently used.

The 240V plug was taped over - I previously didn't even know it was live.
I
would like to get access to a 240V circuit. However, I am concerned about
the
(existing) apparent mixing of 120 and 240 circuits.

Questions:
1) Is is permissible to run 120V and 240V circuits off the same pair of
circuit
breakers - if they are ganged together?
2) If breakers are ganged together, and one leg is overloaded, are they
both
supposed to trip? I performed a little test:
a) with the two breakers separate, an overload (120V) visibly trips one
breaker
- the handle moves to the off position.
b) with the two breakers ganged together, the same overload internally
trips the
same breaker, but the handles don't move, and the other breaker remains
live. Is
this proper behavior? Turning the breakers off, the on again resets the
tripped
breaker.
3) Do breakers 'wear out' or degrade over time? One reason I want a 240V
circuit
is I'm experiencing nuisance tripping when running my table saw under
load. Is
it possible that the breaker is just tripping prematurely?
4) Should I just leave the the whole existing mess alone, get an upgraded
power
drop, main panel and add 240V circuits? This option is MUCH more
expensive...

I was looking for the NEC online, but it looks like I have to buy a copy,
or see
if the library has one...

Thanks!
--
JeffB
remove no.spam. to email

1) No. The 240 should be on its own breaker with no circuits 110
tapping off
of it
2) a)Yes,if you have 2 seperate breakers for a 240 circuit, one will
trip if
overloaded.
b) If I am understanding you correctly, the ganged breaker handle

does not move when tripped. I would say you have a defective
breaker.
3) Yes breakers do wear out over time. Federal Pacific breakers are
known to be defective. If you have this panel,change it.
4) What is the rating of the subpanel in the garage? If its at least
40A you should be ok. Just re-wire the sub-panel so the 240
plug is on its own breaker and the 110 circuits on there own breakers.

There are two relatively inexpensive ways to do this: First is to get half
sized circuit breakers, which would allow you one double pole for the saw
and two single poles for the other stuff. The second is to replace the sub
panel with a four circuit panel and get one double pole full sized breaker
for the saw and two full sized breakers for the other stuff
"I R Baboon" wrote in message
...
i dont know about the rest, but, you CANT run 120 and 240 on the same
circuit. i had the same setup at my house.

"JeffB" wrote in message
...
Existing situation:
The wiring in the garage dates from the 50s or 60s. There is a breaker
box
with
a two 15A breakers that feeds the plugs and lights. There is one duplex
receptacle that is wired for 240V - it's hooked up to both hot wires from
the
two breakers. The rest of the 120V plugs, etc. come off one of the
breakers. The
other breaker is not currently used.

The 240V plug was taped over - I previously didn't even know it was live.
I
would like to get access to a 240V circuit. However, I am concerned about
the
(existing) apparent mixing of 120 and 240 circuits.

Questions:
1) Is is permissible to run 120V and 240V circuits off the same pair of
circuit
breakers - if they are ganged together?
2) If breakers are ganged together, and one leg is overloaded, are they
both
supposed to trip? I performed a little test:
a) with the two breakers separate, an overload (120V) visibly trips one
breaker
- the handle moves to the off position.
b) with the two breakers ganged together, the same overload internally
trips the
same breaker, but the handles don't move, and the other breaker remains
live. Is
this proper behavior? Turning the breakers off, the on again resets the
tripped
breaker.
3) Do breakers 'wear out' or degrade over time? One reason I want a 240V
circuit
is I'm experiencing nuisance tripping when running my table saw under
load. Is
it possible that the breaker is just tripping prematurely?
4) Should I just leave the the whole existing mess alone, get an upgraded
power
drop, main panel and add 240V circuits? This option is MUCH more
expensive...

I was looking for the NEC online, but it looks like I have to buy a copy,
or see
if the library has one...

Thanks!
--
JeffB
remove no.spam. to email

In article , JeffB wrote:

Questions:
1) Is is permissible to run 120V and 240V circuits off the same pair of circuit
breakers - if they are ganged together?

No.

2) If breakers are ganged together, and one leg is overloaded, are they both
supposed to trip?

Yes.

I performed a little test:
a) with the two breakers separate, an overload (120V) visibly trips one breaker
- the handle moves to the off position.

That's good.

b) with the two breakers ganged together, the same overload internally trips
the same breaker, but the handles don't move, and the other breaker remains live.

That's bad.

Is this proper behavior? Turning the breakers off, the on again resets the tripped
breaker.

No. Kinda defeats the purpose of ganging them together, doesn't it, if they
don't *both* move when *one* is tripped?

3) Do breakers 'wear out' or degrade over time? One reason I want a 240V
circuit is I'm experiencing nuisance tripping when running my table saw under load.
Is it possible that the breaker is just tripping prematurely?

Yes, they do wear out, particularly if subjected to repeated overloads.

4) Should I just leave the the whole existing mess alone, get an upgraded power
drop, main panel and add 240V circuits? This option is MUCH more expensive...

You could get a pair of half-height duplex breakers; that would enable you to
run two 120V and one 240V circuits in the same physical space as the two 120V
breakers you now have.

I was looking for the NEC online, but it looks like I have to buy a copy, or
see if the library has one...

Yeah, they don't make it available for free. The library is a good bet; lots
of bookstores have it; and they're up for sale on eBay all the time too.

--
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?

JeffB wrote:
[...]
3) Do breakers 'wear out' or degrade over time? One reason I want a
240V circuit
is I'm experiencing nuisance tripping when running my table saw under
load. Is
it possible that the breaker is just tripping prematurely?

Is your table saw ok with running at 240V? Not being a motor expert, I
would assume that it would need to be wired for a particular voltage.

How about removing the ill-conceived 240V circuit, replacing the unused
15A breaker with a 20, and wiring a new 12-gauge circuit dedicated to
the table saw?

You could make the new breaker a pair of half-height 20's so you'd have
room for a new circuit in the future.

Chip C

"3) Do breakers 'wear out' or degrade over time? One reason I want a
240V circuit is I'm experiencing nuisance tripping when running my
table saw under load. Is it possible that the breaker is just tripping
prematurely?"

Yes, they do wear out over time. Usually it manefests itself in the
form of not tripping as fast as it used to or not tripping at all. The
previous reference to Federal Pacific was incorrect, their two pole
breakers are infamous for not tripping. This person is experiencing
nusiance tripping. Big difference!

Thanks for all the quick replies and good information!

I've looked even further, and the main C/B panel has NO ganged breakers - i.e.
no 240V circuits. The little box in the garage is apparently taps off of a pair
of 40A breakers that feed a subpanel in the house. Everything in there is 120V
circuits. I wonder what the dryer plug (it's dead now) was ever connected to?
What it looks like to me is that I really don't have a way to properly wire any
240V circuit. And no, there's no space left in the main panel. Will I be able to
find breakers that fit into a 50 year old panel?

The saw motors can easily be switched to 240V - which is what I'd really like to
do. But my best choice, without spending lots of money, may be to get a couple
20A plugs in the garage. Or are there slow-blow circuit breakers designed to
handle motor current startup loads?

--
JeffB
remove no.spam. to email

JeffB wrote:
Thanks for all the quick replies and good information!

I've looked even further, and the main C/B panel has NO ganged
breakers - i.e.
no 240V circuits. The little box in the garage is apparently taps off
of a pair
of 40A breakers that feed a subpanel in the house. Everything in
there is 120V
circuits. I wonder what the dryer plug (it's dead now) was ever
connected to?
What it looks like to me is that I really don't have a way to
properly wire any
240V circuit. And no, there's no space left in the main panel. Will I
be able to
find breakers that fit into a 50 year old panel?

The saw motors can easily be switched to 240V - which is what I'd
really like to
do. But my best choice, without spending lots of money, may be to get
a couple
20A plugs in the garage. Or are there slow-blow circuit breakers
designed to
handle motor current startup loads?

--
JeffB
remove no.spam. to email


Sounds like you've quite the to-do list, electrically. All very
do-able.

Doubtless the dryer shared some other pair of breakers that it
shouldn't have.

The only way to find out if you can get breakers for your old panel is
to phone around to find out, or take a breaker to stores to see if they
have one like it.

Each subpanel *really* should be fed off a dedicated pair of linked
breakers in the main panel. As should the dryer and range.

I believe circuit breakers *are* considered slow-blow relative to
fuses; their internal mechanisms are twofold, with an electromagnetic
part that trips immediately on high overload, and a thermal part that
trips after a sustained moderate overload. I don't know if they've
always been like that.

For sure your most likely immediate fix is to find a 20A breaker for
your current panel (and if any breakers are still on the market for it,
a single full size 20A will be) and wire a 20A circuit.

Chip C
Toronto

According to Chip C :
I believe circuit breakers *are* considered slow-blow relative to
fuses; their internal mechanisms are twofold, with an electromagnetic
part that trips immediately on high overload, and a thermal part that
trips after a sustained moderate overload. I don't know if they've
always been like that.

With fuse panels, you're supposed to use "time delay fuses" (aka
"fusetron fuses") for motors.

Circuit breakers respond to overloads like fusetrons do. They've
been like that for a very long time. They've had to be like
that, because "one mode" (bimetallic strip) are too slow for
abrupt high fault current overloads, and would tend to
self-destruct, yet, you want CBs to be reusable.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.