Home>Discussions>ELECTRICAL & LIGHTING>Dead 30 amp circuit/wiring question
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canuk
Re: Dead 30 amp circuit/wiring question
JLMCDANIEL wrote:

Something is not right here. If you have a breaker taking up 2 spaces it's a 240 volt breaker, if you have 2 breakers tied together it's probably a multi-wire branch circuit. Either you have traced the wrong cable or there is something teribly wrong here.

Jack

Double pole or 2 singles tied together --- Wouldn't they both 240 volt ?

JLMCDANIEL
Re: Dead 30 amp circuit/wiring question
canuk wrote:

Double pole or 2 singles tied together --- Wouldn't they both 240 volt ?

Techniquely no, MWB circuits are 2 120 volt circuits with a shared common, there is no connection made between the legs.

I still say there is some information missing. The OP said "The circuit for the outlet is actually two circuit spaces connected together with a 30 amp circuit breaker. The treadmill outlet is the ONLY thing connected to the circuit." and "So I had a 15 amp outlet, on 20 amp wire, connected to a 30 amp circuit breaker. " How did he know it was on this circuit and nothing else was on the circuit? What kind of tester is the OP using and how is he testing the circuit?
Jack

motoguy128
Re: Dead 30 amp circuit/wiring question
JLMCDANIEL wrote:

Something is not right here. If you have a breaker taking up 2 spaces it's a 240 volt breaker, if you have 2 breakers tied together it's probably a multi-wire branch circuit. Either you have traced the wrong cable or there is something teribly wrong here.

Jack

Ding, ding, ding. I read the "30 amp breaker takes 2 spaces" and went ohhh crap, this guy has a problem.

Look at it this way, someone turned that 30Amp 230V circuit for hte dryer into a makeshift (sub-feeder) but without a sub-panel. SO he's tapping into 1 leg of hte 220. THe problem is that hte leg he tapped on to, is now imbalanced. Meaning that the dryer load is being shared on half of that circuit with the treadmill load.

3HP motor on that treadmill? Really? I guess with vairable speed drive you can get away with that. a 3HP motor is abotu 2500Watts are full load. THat's really pushing the limit for a 20A circuit. SO it's either somehow current limits or never using full load. The 3HP rating might be to allow for continuous low speed operation with a speed controller. IT probaly doesn't use more than 1-1/2HP other than at start-up.

Check and see if the mfg of the treadmill recommends a dedicated 30Amp circuit or just a 20Amp circuit.

canuk
Re: Dead 30 amp circuit/wiring question
JLMCDANIEL wrote:

Techniquely no, MWB circuits are 2 120 volt circuits with a shared common, there is no connection made between the legs.

Jack --- Technically they are the same
Indended use ( MWB ) of the circuit aside -- two single pole breakers with a handle tie are on 2 seperate buss legs ( L1 & L2 ) in the panel-- taking up 2 spaces . Measure the voltage between the breaker poles and it's 240.
The same thing as a double pole breaker --- each pole is connected to seperate buss legs ( L1 & L2 ).

With the MWB there is only 120 with reference to the shared neutral and each leg.
Lift ( open ) the neutral in a MWB circuit and you end up with a 240 volt circuit instead of 120.

Not to highjack the thread. :)

canuk
Re: Dead 30 amp circuit/wiring question

I think we all agree this is not an appropriate and safe setup.

Whether the circuit that feeds the treadmill was tapped into at the dryer receptacle box or it may be a double tap at the dryer breaker in the panel , it needs to be removed and run correctly.

canuk
Re: Dead 30 amp circuit/wiring question
motoguy128 wrote:

Ding, ding, ding. I read the "30 amp breaker takes 2 spaces" and went ohhh crap, this guy has a problem.

Look at it this way, someone turned that 30Amp 230V circuit for hte dryer into a makeshift (sub-feeder) but without a sub-panel. SO he's tapping into 1 leg of hte 220. THe problem is that hte leg he tapped on to, is now imbalanced. Meaning that the dryer load is being shared on half of that circuit with the treadmill load.

3HP motor on that treadmill? Really? I guess with vairable speed drive you can get away with that. a 3HP motor is abotu 2500Watts are full load. THat's really pushing the limit for a 20A circuit. SO it's either somehow current limits or never using full load. The 3HP rating might be to allow for continuous low speed operation with a speed controller. IT probaly doesn't use more than 1-1/2HP other than at start-up.

Check and see if the mfg of the treadmill recommends a dedicated 30Amp circuit or just a 20Amp circuit.

Treadmills typically have DC motors.
The current draw will vary on the load -- speed , weight , etc.

Most treadmills that I'm familar with require either a dedicated 15 amp ( residential ) or 20 amp ( usually the commercial units ) circuit.

JLMCDANIEL
Re: Dead 30 amp circuit/wiring question
canuk wrote:

Jack --- Technically they are the same
Indended use ( MWB ) of the circuit aside -- two single pole breakers with a handle tie are on 2 seperate buss legs ( L1 & L2 ) in the panel-- taking up 2 spaces . Measure the voltage between the breaker poles and it's 240.
The same thing as a double pole breaker --- each pole is connected to seperate buss legs ( L1 & L2 ).

With the MWB there is only 120 with reference to the shared neutral and each leg.
Lift ( open ) the neutral in a MWB circuit and you end up with a 240 volt circuit instead of 120.

Not to highjack the thread. :)

Using your analogy, if you have two circuits in a room and each is on a different leg, the room is wired 240 volts.

Jack

canuk
Re: Dead 30 amp circuit/wiring question
JLMCDANIEL wrote:

Using your analogy, if you have two circuits in a room and each is on a different leg, the room is wired 240 volts.

Jack

Without a neutral -- yes

Re: Dead 30 amp circuit/wiring question
Dmurr33 wrote:

Just discovered that my dryer is on the same circuit, which now explains why it's a 30 amp breaker. The dryer is working, which means the breaker is obviously working. When I hold my tester to the wire for the outlet, I get nothing, so perhaps the wire overheated and melted somewhere.

Sounds like you have to run #10-2 w/ ground off a 30A 2P breaker to your dryer.

And, connect the 12-2 to a 20A SP breaker to a dedicated 20A receptacle, since it will be the only receptacle on a 20A breaker. I assume the wire has a ground..if not it too should be replaced.

Good Luck from Columbiana, Alabama
Maurice Turgeon, http://thesemi-retiredelectrician.com

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