Help with electric heater connection!!

[Beekerc]

unless you have an outdated panel - last year i had to replace a couple of 15A breakers in my circa 1968 Federal Pacific panel to the tune of $27/each - circuit breakers are cheap (<$5 for most single pole 15A and 20A). I now have a Square-D/Home-Line panel and breakers are around $4/each.

from my lay perspective, if you've already got 10/2 wire, which is required for a 30A circuit, why on earth would you not put a 30A breaker there? I just picked one up (i'm running a new 30A line for my servers) for $3.97 at the big box store with orange lettering, the price on the L5-30R receptacle was the killer though. I know that you can put a lower rated breaker than the wire is capable of carrying - ie a 15A breaker on a circuit wired with 12ga - but the point is why would you? If your wattage or ampacity is borderline for the breaker (but within the limits of the wire) why not err on the side of caution and put in the larger capacity breaker? the real problem is when you discover that you're routinely pulling more than 12A (80% of 15A) over 14 gauge wire and the choices become - re-wire with 12 gauge or reduce the load(s).

after making sure the circuit wire gauge is correct, remember - breakers are cheap, rebuilding is expensive.

just my humble, and uncertified, ) $0.02 worth.
BeekerC

 

[Jar546]

unless you have an outdated panel - last year i had to replace a couple of 15A breakers in my circa 1968 Federal Pacific panel to the tune of $27/each - circuit breakers are cheap (<$5 for most single pole 15A and 20A). I now have a Square-D/Home-Line panel and breakers are around $4/each.

from my lay perspective, if you've already got 10/2 wire, which is required for a 30A circuit, why on earth would you not put a 30A breaker there? I just picked one up (i'm running a new 30A line for my servers) for $3.97 at the big box store with orange lettering, the price on the L5-30R receptacle was the killer though. I know that you can put a lower rated breaker than the wire is capable of carrying - ie a 15A breaker on a circuit wired with 12ga - but the point is why would you? If your wattage or ampacity is borderline for the breaker (but within the limits of the wire) why not err on the side of caution and put in the larger capacity breaker? the real problem is when you discover that you're routinely pulling more than 12A (80% of 15A) over 14 gauge wire and the choices become - re-wire with 12 gauge or reduce the load(s).

after making sure the circuit wire gauge is correct, remember - breakers are cheap, rebuilding is expensive.

just my humble, and uncertified, ) $0.02 worth.
BeekerC

You should have replaced your FPE StabLok panel instead of tracking down UNLISTED aftermarket breakers for a panel that is from a company that has been out of business for 20 years.

 

[Sponsor]

 

[SewerRatz]

If the voltage drops, the fixed resistance of a heating element does not change, so the circuit current goes down....not up.

Jimbo,

Its been a while since I had to deal with Ohms law. But power is equal to Voltage X Amperage

P = V x A

So if the voltage changes the math would be
A = P / V
In this case
4000 / 240 = 16.66667
4000 / 220 = 18.18182

Now I may be looking at this from the wrong point of view, like I said it has been a long time since I messed with Ohms law. I used to be an electrical tech in the Army many many years ago.

So it would draw more amperage if the voltage goes down if the unit is designed to draw a set wattage.

 

[SewerRatz]

Jimbo,

I am sorry I dug out one of my old books. If you are correct if the resistance is fixed the and the voltage drops so will the amperage.

A = V / R

Which would also mean if the voltage drops which causes the amperage to drop so will the output wattage.

P = V x A

Again I am sorry for doubting what you said. I had to refresh them brain cells of mine.

 

[Redwood]

A resistance load will draw lower with lower voltage.

 

[Leejosepho]

If you can tolerate a couple of popups, here is the Ohm's-Law calculator I use:
http://www.angelfire.com/pa/baconbacon/page2.html

Put in any two numbers available and you will end up with volts, amps, ohms and watts.

 

[Leejosepho]

I know you can put a lower rated breaker than the wire is capable of carrying - ie a 15A breaker on a circuit wired with 12ga - but the point is why would you? If your wattage or ampacity is borderline for the breaker (but within the limits of the wire) why not err on the side of caution and put in the larger capacity breaker? the real problem is when you discover that you're routinely pulling more than 12A (80% of 15A) over 14 gauge wire and the choices become - re-wire with 12 gauge or reduce the load(s).

I am still sorting some things out here, but at least now I do understand what you just said about "routinely pulling more than 80%".

My house has wire from at least three eras, and I do not trust some of the oldest wire to carry 20 amps even though it is (or it at least appears to be) #12 wire. So, and with the electrician's agreement when he installed a new panel a couple of years ago, I have only 15-amp breakers for all 120-volt circuits (except for one new one). At least in theory, that limits the voltage available to that old wire, but in reality, even a 15-amp breaker can let enough through to cause trouble ... ?!?

In any case, none of my breakers are even warm to the touch, and I have enough circuits in this small house to spread the overall load around fairly well.

 

[JWelectric]

I am still sorting some things out here, but at least now I do understand what you just said about "routinely pulling more than 80%".

My house has wire from at least three eras, and I do not trust some of the oldest wire to carry 20 amps even though it is (or it at least appears to be) #12 wire. So, and with the electrician's agreement when he installed a new panel a couple of years ago, I have only 15-amp breakers for all 120-volt circuits (except for one new one). At least in theory, that limits the voltage available to that old wire, but in reality, even a 15-amp breaker can let enough through to cause trouble ... ?!?
In any case, none of my breakers are even warm to the touch, and I have enough circuits in this small house to spread the overall load around fairly well.

I think I know what you are trying to say even though you have said it wrong.

A #12 conductor installed on a 120 volt circuit will have 120 volts present no matter the size overcurrent device installed. A 15 amp breaker does not limit the voltage any more than a 150 amp breaker. What a 15 amp breaker will limit is the amount of current (amps).

If the insulation of the conductors has broken down using a smaller overcurrent device will not help anything at all except limit the load that can be attached.

Voltage is the amount of pressure that is pushing the amperage down the conductor. If the pressure becomes too great the conductor burst open and then we have a problem. If the insulation has broken down then the only solution is to either drop the voltage to a safe level or replace the conductor.

Think of it like a water line. Should I decide to install CPVC plumbing in my home which has a water pressure of 60 lbs I can expect to have problems in about five years as the CPVC will get old and brittle and leaks will spring forward.
But if I reduce the pressure to about 10 lbs this junk might last for 20 years.

The problem with electricity is that we can not regulate the amount of pressure (volts) as the equipment that we use mandates the amount of pressure (volts). When the insulation starts to break down we can not reduce the amount of pressure (voltage) applied therefore the only safe fix is to replace the wiring. Changing the overcurrent device changes nothing except the size of the overcurrent device.

 

[Leejosepho]

I think I know what you are trying to say even though you have said it wrong.

Yes, I did, and yes, you do.

I understand "volts are like pressure" and "amps are like current flow" and "watts are like volume", and I understand volts/pressure can destroy a weak or ill-suited conductor or pipe.

What a 15 amp breaker will limit is the amount of current (amps).

Understood, and it is the "friction" of those amps passing through (back and forth) that can cause heat, correct?

If the insulation of the conductors has broken down using a smaller overcurrent device will not help anything at all except limit the load that can be attached.

Yes ... but that could in effect also at least help to keep an old wire from overheating and pushing its heat out through its poor or weak insulation, correct?

If the insulation has broken down then the only solution is to either drop the voltage to a safe level or replace the conductor.

Since a conductor can do its job with no insulation at all as long as it does not short-circuit or overheat near a combustible, the issue there would actually be friction-amps rather than the condition of any mere covering, correct?

Think of it like a water line.

Yes, and water lines are like bare wire: no insulation at all.

When the insulation starts to break down we can not reduce the amount of pressure (voltage) applied therefore the only safe fix is to replace the wiring.

Yes, in relation to any short-circuit or ignition issues, but not in relation to a wire's inherent ability to carry current, correct?

Changing the overcurrent device changes nothing except the size of the overcurrent device.

... and "limit the load that can be attached", thereby limiting the heat-producing friction that might otherwise be possible, correct?

My point here is not to argue needlessly, but to be sure the professional electrician who agreed it was a good idea to use only 15-amp breakers on my old wiring was not wrong while thereby essentially confirming my thought of doing that in order to reduce the likelihood of a fire from an overheated wire.

 

[Jar546]

What should have happened Lee is that all of the circuits should have been tested with a megger and if there were any problems then they should have been properly repaired.

If you want to do something worthwhile rather than downsize a breaker which is like saying "when we kill you, do you want to be shot in the head with a .45 or a 9mm?" because they both do the same things just at different levels.

AFCI Combo circuit breakers would have been a much better choice rather than downsizing from a 20 to a 15. 15amps makes just about as much heat and spark as 20.

 

[JWelectric]

Yes, I did, and yes, you do.

I understand "volts are like pressure" and "amps are like current flow" and "watts are like volume", and I understand volts/pressure can destroy a weak or ill-suited conductor or pipe.




Understood, and it is the "friction" of those amps passing through (back and forth) that can cause heat, correct?



Yes ... but that could in effect also at least help to keep an old wire from overheating and pushing its heat out through its poor or weak insulation, correct?



Since a conductor can do its job with no insulation at all as long as it does not short-circuit or overheat near a combustible, the issue there would actually be friction-amps rather than the condition of any mere covering, correct?



Yes, and water lines are like bare wire: no insulation at all.



Yes, in relation to any short-circuit or ignition issues, but not in relation to a wire's inherent ability to carry current, correct?



... and "limit the load that can be attached", thereby limiting the heat-producing friction that might otherwise be possible, correct?

My point here is not to argue needlessly, but to be sure the professional electrician who agreed it was a good idea to use only 15-amp breakers on my old wiring was not wrong while thereby essentially confirming my thought of doing that in order to reduce the likelihood of a fire from an overheated wire.

No Lee, reducing the size of overcurrent device from a 20 to a 15 on a #12 wire does not make it safer and if an electrician has told you it does then he/she is far from being correct.

Yes the electron flow does cause heat but a #12 copper conductor has the ability to carry up to and including 30 amps.
What limits the amount of current on a conductor other than its size is its insulation.

 

[Leejosepho]

AFCI Combo circuit breakers would have been a much better choice rather than downsizing from a 20 to a 15. 15 amps makes just about as much heat and spark as 20.

No Lee, reducing the size of overcurrent device from a 20 to a 15 on a #12 wire does not make it safer and if an electrician has told you it does then he/she is far from being correct.

What he actually said when I mentioned using all 15s was, "Makes sense to me" ... but now I see the reality of "15 amps makes just about as much heat and spark as 20." And, that is essentially what happened in the middle of the night about a year ago when something exploded in the ceiling and near a fan. I never could find the bad spot in that old circuit, so I just cut it out altogether and ran some new wire.

Overall, I thank you, gents!

 

[frenchelectrican]

To., OP.,

C'est simple get 25 or 30 amp double pole breaker with #10-W/G romex cable that will meet the code no question asked.

While still on the same subject please do remark the white conductor with either red , black , blue marker to indentify it is a hot conductor instead or netrual conductor.

Merci,Marc