breaker/wire size for heating element

[Owly055]

depends on the wiring of the house, 10/2 comes with a copper ground thats used as both ground and neutral, 10/3 has a extra isolated ground. older homes only need 10/2 there is no isolated ground in the fuse box

That is completely wrong.............. You NEVER use the ground for a neutral.........


H.W.

 

[augiedoggy]

Nonmetallic building wire like Romex is rated for how many current carrying conductors it has. 10/2 is blk,wht,bare ground. For portable cables like SO and SJ, the same conductor count is called 10/3. I don't know why but just saying so you don't end up with actual 2-wire cable.

Your completely right... I wasnt aware of that.

 

[Ozarks Mountain Brewery]

That is completely wrong.............. You NEVER use the ground for a neutral.........


H.W.

I understand what your saying and thats why they changed the codes....but if you trace back any 240 wiring in an oder home like mine 50 years old, the fuse box does not have a separate ground, all grounds are hooked to the common bus so using 10/3 wire you would need to start a separate ground to earth bus and run that from the fuse box to a ground rod at least 4 feet or more or else your just wasting money

 

[augiedoggy]

That is mostly because of Vdrop. Both in the wire and the element itself. The difference between 240V and 235V is roughly a 4% drop in power draw/heating power for the element and with a big load on the breaker, it is perfectly realistic to think you might have a 5v sag on a 240v circuit with something like a 20A load, which is enough to drop you from 4500w to 4300w.

yes very true I am aware of that... and some building are wired to only produce 208v but those are usually commercial buildings in the US...

 

[azazel1024]

I understand what your saying and thats why they changed the codes....but if you trace back any 240 wiring in an oder home like mine 50 years old, the fuse box does not have a separate ground, all grounds are hooked to the common bus so using 10/3 wire you would need to start a separate ground to earth bus and run that from the fuse box to a ground rod at least 4 feet or more or else your just wasting money

Yes, all grounds ARE hooked to the neutral bus bar, in the main breaker. That is the proper way to do it.

A ground wire is not connected to directly to the neutral anywhere. That would be dangerous as hell. The ground and neutral bus bars are connected in the main panel however, as they need to be.

Many very old homes have NO ground wire and no ground bus bar. Generally about late 1950's to mid 1960's homes had undersized grounds (generally 2-4AWG smaller than the conductors) and then in the mid/late 1960's code changes and the ground had to be the same size as the conductors.

The grounds should not be terminated at the neutral bar, they should be terminated at a ground bus bar, which is bonded to the neutral bus bar. The ground bus bar should then also be connected to an earthed rod or rods (minimum of 4ft apart if multiple) in size/depth such to have a maximum of 20ohms (maybe it is 25) of resistance to ground.

You would not use 10/3 wire, you'd use 10AWG single conductor wire to connect to the ground rods.

You never, ever, ever want to connect the neutral and ground anywhere other than in the main panel. If you do that and a neutral and hot wire are improperly reversed on the circuit and you'll A) trip the breaker and/or B) electrocute yourself if you touch the chasis of anything grounded.

In several dozen homes and buildings I've done electrical work in, I think I'd have to at a minimum pull off my socks to count the number of times I've seen an outlet or switch with neutral and hot reversed.

 

[Owly055]

Yes, all grounds ARE hooked to the neutral bus bar, in the main breaker. That is the proper way to do it.

A ground wire is not connected to directly to the neutral anywhere. That would be dangerous as hell. The ground and neutral bus bars are connected in the main panel however, as they need to be.

Many very old homes have NO ground wire and no ground bus bar. Generally about late 1950's to mid 1960's homes had undersized grounds (generally 2-4AWG smaller than the conductors) and then in the mid/late 1960's code changes and the ground had to be the same size as the conductors.

The grounds should not be terminated at the neutral bar, they should be terminated at a ground bus bar, which is bonded to the neutral bus bar. The ground bus bar should then also be connected to an earthed rod or rods (minimum of 4ft apart if multiple) in size/depth such to have a maximum of 20ohms (maybe it is 25) of resistance to ground.

You would not use 10/3 wire, you'd use 10AWG single conductor wire to connect to the ground rods.

You never, ever, ever want to connect the neutral and ground anywhere other than in the main panel. If you do that and a neutral and hot wire are improperly reversed on the circuit and you'll A) trip the breaker and/or B) electrocute yourself if you touch the chasis of anything grounded.

In several dozen homes and buildings I've done electrical work in, I think I'd have to at a minimum pull off my socks to count the number of times I've seen an outlet or switch with neutral and hot reversed.

Most folks do not understand electricity, or wiring, either AC or DC, and discount the importance of ground (DC), or neutral (AC), as somehow not carrying the same load as the positive (DC), or Hot AC lead. They in fact carry exactly the same current load...... and are the same gauge for this reason. The ground wire on the other hand is not a load carrying wire, and often is lighter. People get away with a lot of "sins" with wiring, but there really is only one safe way to do it.


H.W.

 

[Onkel_Udo]

In several dozen homes and buildings I've done electrical work in, I think I'd have to at a minimum pull off my socks to count the number of times I've seen an outlet or switch with neutral and hot reversed.

Warning, Thread degradation even further

Honestly, I have never owned a home where less than 10% of the outlets had it reversed when I purchased it. Granted, my first home had 6 outlets in its 1100 sq feet (but one gas nipple per room) and a whopping 4 circuit fuse box.

FYI, not every instance has appeared to be homeowner installed either. there are certain tell-tales of the local Union guys doing work (practices not skilled homeowner would use because) and two of my four outlets that were reversed in my current house had every indication a "Pro" installed them.

 

[Ozarks Mountain Brewery]

Yes, all grounds ARE hooked to the neutral bus bar, in the main breaker. That is the proper way to do it.

A ground wire is not connected to directly to the neutral anywhere. That would be dangerous as hell. The ground and neutral bus bars are connected in the main panel however, as they need to be.

Many very old homes have NO ground wire and no ground bus bar. Generally about late 1950's to mid 1960's homes had undersized grounds (generally 2-4AWG smaller than the conductors) and then in the mid/late 1960's code changes and the ground had to be the same size as the conductors.

The grounds should not be terminated at the neutral bar, they should be terminated at a ground bus bar, which is bonded to the neutral bus bar. The ground bus bar should then also be connected to an earthed rod or rods (minimum of 4ft apart if multiple) in size/depth such to have a maximum of 20ohms (maybe it is 25) of resistance to ground.

You would not use 10/3 wire, you'd use 10AWG single conductor wire to connect to the ground rods.

You never, ever, ever want to connect the neutral and ground anywhere other than in the main panel. If you do that and a neutral and hot wire are improperly reversed on the circuit and you'll A) trip the breaker and/or B) electrocute yourself if you touch the chasis of anything grounded.

In several dozen homes and buildings I've done electrical work in, I think I'd have to at a minimum pull off my socks to count the number of times I've seen an outlet or switch with neutral and hot reversed.

without going into specific detail, thats exactly what I was saying, you just explained it in or detail, thanks

 

[azazel1024]

Yup, almost all of the reversed work I have seen looked to have been done by the original electrical contractor. Or, more likely than not, their under paid and undertrained "apprentice(s)".

I have seen a few homeowner hackjobs that have scared the bejesus out of me where I refused to turn the breaker back on until I had remediated the problem.

Most of the general shoddy work has been original construction for sure. Including a hotwater heater which didn't have the ground properly connected (by which I mean WAS NOT). You want to know how I found out??? It involved a tiny leak in jacket that ran over an element. Yeah, it hurt like a son-of-a-b.

Just took touching the body of the water heater in my barefeet, concrete was moist enough to ground me.

 

[Bowtiebrewery]

Wow this thread got out of hand quick. Not one Licensed Electrician has chimed in?

A lot of mis-information here. Can I make a recommendation for the OP. Just follow Kal's setup advice regarding the wiring that he uses because he followed code on just about everything and documented it. He used 10/3 for the wiring going from his outlets on his control panel to the elements. He is using 5500w elements, and has never had any issues at all.
He also uses 10GA singular wireing for the wires going from his Bus Bars to the Outlets for his Elements inside the panel.

He uses 14ga for everything else.

Are they overkill? Maybe... But has he had any issues with arcing or wires melting, or breakers tripping? No... SOOOOOOO

Forget the Bullsh*t (sorry but a lot of the comments in this thread are) and just do that... You will be just fine.

And final piece of advice... If you don't feel confident in this, contract an electrician to help you or do it for you.

 

[podz]

THERE IS NO SUCH THING AS TOO HEAVY

Yes, there is. If your wire is too fat, the short-circuit current won't be enough to trip your breaker. The breaker will pass overrated current, which can heat up the northbound side of your wire. It's not rocket science. And no need to shout misinformation.

 

[podz]

Wow this thread got out of hand quick. Not one Licensed Electrician has chimed in?

Perhaps we can invoke @Ischiavo.

 

[Bowtiebrewery]

I would ask a buddy of mine to chime in, but unfortunately being an electrician he is never online. Meh...

 

[Onkel_Udo]

Wow this thread got out of hand quick. Not one Licensed Electrician has chimed in?

Honestly, how do you know?

I was "licensed" at one time in Oklahoma. Written test only and was good for one year during which you had to do you practical training and 9 hours of approved continuing education. Regardless, it said "Licensed Residential Electrician" and I was allowed to pull permits for a whole year. I managed less than a 1/3 rd of the "practical" hours when I realized I did not want to do that for a living.

Practicing professional electrician...not so much

 

[Bowtiebrewery]

Honestly, how do you know?

I was "licensed" at one time in Oklahoma. Written test only and was good for one year during which you had to do you practical training and 9 hours of approved continuing education. Regardless, it said "Licensed Residential Electrician" and I was allowed to pull permits for a whole year. I managed less than a 1/3 rd of the "practical" hours when I realized I did not want to do that for a living.

Practicing professional electrician...not so much

To my knowledge there are several tests and certification levels associated with being an Electrician. Several states have electrical contractor licenses which you can test for. Primary purposes are to pull permits.

My bad for assuming none had chimed in, but also I should have been more clear. My comment should have been

"I'm surprised no E-1 Licensed Electicians have not chimed in here" My friend happens to be E-1 Certified.

In CT there are 2 licenses... E1 AND E2, Master and Apprentice. You can't practice or wire as an E2 unless employed by an E1.

So that being said, I would look for input from someone on the level of an E1 if I was concerned

 

[Onkel_Udo]

To my knowledge there are several tests and certification levels associated with being an Electrician. Several states have electrical contractor licenses which you can test for. Primary purposes are to pull permits.

My bad for assuming none had chimed in, but also I should have been more clear. My comment should have been

"I'm surprised no E-1 Licensed Electicians have not chimed in here" My friend happens to be E-1 Certified.

In CT there are 2 licenses... E1 AND E2, Master and Apprentice. You can't practice or wire as an E2 unless employed by an E1.

So that being said, I would look for input from someone on the level of an E1 if I was concerned

Valid response. To muddy the waters even more, for almost two years I was an electrical inspector for US military installations overseas on a code (I think 2000 IET but it might have been earlier) I knew only from the books I read on the flight over to Kuwait. My job was to ensure the grounding and bonding upgrades that three electrical contractors were retrofitting throughout our "contigency operations locations".

Electrical work is a little bit of knowledge, a lot of tables and a lot of common sense. Oh, and acronyms out the wazooo.

 

[Owly055]

Yes, there is. If your wire is too fat, the short-circuit current won't be enough to trip your breaker. The breaker will pass overrated current, which can heat up the northbound side of your wire. It's not rocket science. And no need to shout misinformation.

This is NOT true..... not at all. The current passing through your circuit breaker is what heats the internal thermal sensor. That current is completely unrelated to the wire sizing external to the breaker........ I don't know where you came up with that bit of misinformation, but it is absolute bunk!! External wiring size has no bearing at all on the operation of a circuit breaker...... that's beyond absurd!! It's utter hogwash.


H.W.

 

[RufusBrewer]

Yes, there is. If your wire is too fat, the short-circuit current won't be enough to trip your breaker. The breaker will pass overrated current, which can heat up the northbound side of your wire. It's not rocket science. And no need to shout misinformation.

I hope you can understand my confusion on this one.

A circuit breaker is rated for let's use 20 amp as an example. The breaker will hold nominally 20 amps. As you draw more than the nominal 20 amps, the breaker will trip. The more above 20 amps you go, the quicker the breaker will trip. Example: 135% above the rating might be a couple minutes, 200% might be a couple seconds, 1000% trips close to instantly.

Your position is that it is possible to draw so much current that the circuit will not trip fast enough to avoid damage on the north (source?) side of the breaker. And this level of of damge indcuing current is the result wiring capable of drawing too much current. Due to it's large size and low resistence.

The question I have: In our example of a 20 amp breaker, (120 VAC) how big of a wire is too big?

Now I am going to do some calcualtions:

Looking a a wire gauge chart
12 gauge wire is ~1.6 ohms/1,000 feet
6 gauge is ~ 0.40 ohms/1,00 feet.

100 foot run of 12 gauge, 120 volts shorted = 375 amps @ 45 K watts
100 foot run of 6 gauge, 120 volts shorted = 1,500 amps @ 180 K watts

The second value, the higher power, is enough to damage the north side of the breaker when the first one would not.

This is where I get my puzzlements. If you have a 25 foot run of 12 gauge shorted out, you would get 1,500 amp @ 180 K watts. Seems to me it is more complicated than "Do not use that wire gauge, it is too big,"

 

[podz]

This is NOT true..... not at all. The current passing through your circuit breaker is what heats the internal thermal sensor. That current is completely unrelated to the wire sizing external to the breaker........ I don't know where you came up with that bit of misinformation, but it is absolute bunk!! External wiring size has no bearing at all on the operation of a circuit breaker...... that's beyond absurd!! It's utter hogwash.


H.W.

There you go.

http://en.wikipedia.org/wiki/Prospective_short_circuit_current

 

[Bobby_M]

I stayed at a Holiday Inn once.

 

[Ozarks Mountain Brewery]

I am Groot

 

[ingchr1]

The question I have: In our example of a 20 amp breaker, (120 VAC) how big of a wire is too big?

Now I am going to do some calcualtions:

Looking a a wire gauge chart
12 gauge wire is ~1.6 ohms/1,000 feet
6 gauge is ~ 0.40 ohms/1,00 feet.

100 foot run of 12 gauge, 120 volts shorted = 375 amps @ 45 K watts
100 foot run of 6 gauge, 120 volts shorted = 1,500 amps @ 180 K watts

The second value, the higher power, is enough to damage the north side of the breaker when the first one would not.

This is where I get my puzzlements. If you have a 25 foot run of 12 gauge shorted out, you would get 1,500 amp @ 180 K watts. Seems to me it is more complicated than "Do not use that wire gauge, it is too big,"

Calculating the available short circuit current is more complicated than that. You would need information all the way back to the transformer on the pole outside your house. This includes transformer data, cable sizes and cable lengths. Basics of short circuit current: http://ecmweb.com/content/short-circuit-current

In any case, you're not going to cause your breaker to not trip under a short circuit by using upsized wire.

 

[Onkel_Udo]

I stayed at a Holiday Inn once.

Yes, but was it Holiday Inn Express?

 

[maxtor]

Wow this thread got out of hand quick. Not one Licensed Electrician has chimed in?

A lot of mis-information here. Can I make a recommendation for the OP. Just follow Kal's setup advice regarding the wiring that he uses because he followed code on just about everything and documented it. He used 10/3 for the wiring going from his outlets on his control panel to the elements. He is using 5500w elements, and has never had any issues at all.
He also uses 10GA singular wireing for the wires going from his Bus Bars to the Outlets for his Elements inside the panel.

He uses 14ga for everything else.

Are they overkill? Maybe... But has he had any issues with arcing or wires melting, or breakers tripping? No... SOOOOOOO

Forget the Bullsh*t (sorry but a lot of the comments in this thread are) and just do that... You will be just fine.

And final piece of advice... If you don't feel confident in this, contract an electrician to help you or do it for you.

"Kal's setup advice" ?? Who is kal and where is this advice?

 

[augiedoggy]

Wow this thread got out of hand quick. Not one Licensed Electrician has chimed in?

A lot of mis-information here. Can I make a recommendation for the OP. Just follow Kal's setup advice regarding the wiring that he uses because he followed code on just about everything and documented it. He used 10/3 for the wiring going from his outlets on his control panel to the elements. He is using 5500w elements, and has never had any issues at all.
He also uses 10GA singular wireing for the wires going from his Bus Bars to the Outlets for his Elements inside the panel.

He uses 14ga for everything else.

Are they overkill? Maybe... But has he had any issues with arcing or wires melting, or breakers tripping? No... SOOOOOOO

Forget the Bullsh*t (sorry but a lot of the comments in this thread are) and just do that... You will be just fine.

And final piece of advice... If you don't feel confident in this, contract an electrician to help you or do it for you.

it got out of hnd because many poster including myself (and you btw since the op is using a 4500w element which draws 4 amps less than a 5500w you mentioned) that means he has an 18-19amp load at the very most

Most here agree that the correct rated type and size cable here is 25a SJ or SO cable... 10 or 12 gauge will be perfectly safe and meet code... I have been using 25a rated 12 gauge for two years and nothing gets hot because 18 amps through a cable designed for up to 25 is FINE regardless of the silly comments that keep insisting 10 gauge 30 amp wire is needed I'm guessing some just dont do the math and repeat what they read without question.

The thread is just going on because people here are bored and like to argue over silly petty things.. (including myself apparently since I just felt the need to correct you.)
and using 14 guage (rated for 15 amps) wire for pids power which draws less than 1/2 an amp is completely unecessary..especially when you look at the plastic devices they are wired too. As long as the circuit is protected with the correct size fuse or breaker there is no logical reason for it that I know of... I believe anything under 16 gauge does not meet code for ac use but im not sure if that is stand alone or if it still applied inside an electrical device such as a control panel. I used 18 and even 20 for certain indicator lights and such... I have no plans to have my panel UL listed and I know its just as safe so theres no point.

kal does a lot of other things that are not commonly done like his element enclosures which were nice as the time but there are safer methods out there now in my opinion.... he also charged over 2 grand for less functionality than the one I built for $300.... He would make a good engineer working for the government.. I get that he wanted it as safe as possible since non electrical people would be assembling them and it also means less chance of any type of maintenance or failure but it doesnt mean anything else is unsfe or wrong.

 

[augiedoggy]

"Kal's setup advice" ?? Who is kal and where is this advice?

I should put this quote in my signature...lol he is the grand poobah of sorts.... The guy who basically took electric brewing mainstream...
his site,

Theelectricbrewery.com

lots of great info and top quality but top dollar options.

 

[RufusBrewer]

Calculating the available short circuit current is more complicated than that. You would need information all the way back to the transformer on the pole outside your house. This includes transformer data, cable sizes and cable lengths. Basics of short circuit current: http://ecmweb.com/content/short-circuit-current

In any case, you're not going to cause your breaker to not trip under a short circuit by using upsized wire.

I did some research and figured out what the "Prospective short circuit current" is all about. You are correct. They are measuring the output impedance of the source power coming into the building. Calculating if the source provide a current in excess of what the breaker will operate properly.

I was trying to sort out the statement "Too big of wire is dangerous!" in the context of making an electric brew system. What ever calculations and testing to be done with regards "Prospective Short Circuit Current" would have been addressed when the breaker was installed.

Putting "too big" of a conductor down stream and after the testing & calculations does not change anything. In fact the testing and calculations assumes you are going to put a zero ohm cable on the system and everything will work properly.

 

[azazel1024]

Yes, there is. If your wire is too fat, the short-circuit current won't be enough to trip your breaker. The breaker will pass overrated current, which can heat up the northbound side of your wire. It's not rocket science. And no need to shout misinformation.

That's...um, the opposite of what would happen. The larger the diameter of the wiring, the lower the resistance of the wire, the HIGHER the short circuit current. So "too heavy" AWG wire would actually trip the breaker sooner.

The two issues with too large wiring is that it won't fit properly on underrated terminals, which can be hazardous. The second is it is wasteful. 10/2 costs more than 12/2 costs more than 14/2. Also harder to work with, but that is generally a pretty tertiary concern.

Generally a step above what you need isn't going to be a big deal. The only super hazardous thing is to have oversized breakers vs the wiring employeed. As this can result in too much heat generated by the wiring. Generally you aren't looking at that wiring starting a fire (as even a good double load on the wire isn't likely to produce temperatures in excess of 60C in the wire even over time, which is what most/all romex is rated for, if it isn't 80 or 100C romex)...but it CAN cause the wiring to expand too much, which is a termination issue and can result in shorts. Yes, there are instances where it is possible for wire to be installed in such a way that double the rated load can eventually melt the wiring, but that is REALLY hard to accomplish (in a reasonably insulated location combined with a high temperature location).

It is the expansion of the wire that is the primary concern, melting the sheathing is very secondary. As that generally takes a 3-4x over rated load to eventually generate that much heat. Breakers are designed to carry loads between 125-150% of the rated capacity for a few minutes before tripping from thermal load. They are designed to trip immediately with loads roughly 2x rated capacity, through magnetic tripping. There are some breakers which are magnetic only and some which are thermal only. Most/all residential breakers are the combined type. It is to allow temporary overloads, such as motors starting or lugging, to be carried by the circuit as short duration overloads are not dangerous to the wiring, outlets, etc. However, things like a short circuit or massive overload (like say a 2kw motor trying to be carried on a 15A 120v circuit, which is likely to have a 3-4kw starting surge) should trip the breaker immediately.

If the breaker AND the wiring AND the recepticals are all oversized for your planned load, the only real issue is you are spending more and having more hassle on installation than you need. So long as you don't mind that, no big deal at all. Of course you need to ensure that your end devices have their own breakers or fuses if appropriate and they need protection.

 

[azazel1024]

I hope you can understand my confusion on this one.

A circuit breaker is rated for let's use 20 amp as an example. The breaker will hold nominally 20 amps. As you draw more than the nominal 20 amps, the breaker will trip. The more above 20 amps you go, the quicker the breaker will trip. Example: 135% above the rating might be a couple minutes, 200% might be a couple seconds, 1000% trips close to instantly.

Your position is that it is possible to draw so much current that the circuit will not trip fast enough to avoid damage on the north (source?) side of the breaker. And this level of of damge indcuing current is the result wiring capable of drawing too much current. Due to it's large size and low resistence.

The question I have: In our example of a 20 amp breaker, (120 VAC) how big of a wire is too big?

Now I am going to do some calcualtions:

Looking a a wire gauge chart
12 gauge wire is ~1.6 ohms/1,000 feet
6 gauge is ~ 0.40 ohms/1,00 feet.

100 foot run of 12 gauge, 120 volts shorted = 375 amps @ 45 K watts
100 foot run of 6 gauge, 120 volts shorted = 1,500 amps @ 180 K watts

The second value, the higher power, is enough to damage the north side of the breaker when the first one would not.

This is where I get my puzzlements. If you have a 25 foot run of 12 gauge shorted out, you would get 1,500 amp @ 180 K watts. Seems to me it is more complicated than "Do not use that wire gauge, it is too big,"

Keep in mind, that is with a DIRECT connection. Shorts are rarely full connection, you typically get a brush between the wires causing a short circuit, which will pop the breaker immediately.

It is certainly possible to damage a breaker from a short and the higher the short circuit current is, the more likely it is. However, I've never once seen a breaker fail from a short in the closed position. I suppose this is completely possible. That said too, your main breaker will trip if the breaker fails in the closed position if you have a true short circuit sufficient to damage a branch circuit breaker. Unless you are running some 00 AWG wire or something as a branch circuit, you are not going to generate sufficient current to damage the main breaker.

 

[Owly055]

I did some research and figured out what the "Prospective short circuit current" is all about. You are correct. They are measuring the output impedance of the source power coming into the building. Calculating if the source provide a current in excess of what the breaker will operate properly.

I was trying to sort out the statement "Too big of wire is dangerous!" in the context of making an electric brew system. What ever calculations and testing to be done with regards "Prospective Short Circuit Current" would have been addressed when the breaker was installed.

Putting "too big" of a conductor down stream and after the testing & calculations does not change anything. In fact the testing and calculations assumes you are going to put a zero ohm cable on the system and everything will work properly.

Note the statement used to justify the claim that too large a conductor was dangerous:


"If your wire is too fat, the short-circuit current won't be enough to trip your breaker. The breaker will pass overrated current, which can heat up the northbound side of your wire."

Everything about it is absurd. A larger conductor will have a HIGHER short-circuit current, not a lower short-circuit, current due to it's lower resistance.

I must confess that I found absolutely nothing on the Wikipedia page that could be construed to support the contention it was intended to support.....(not that Wikipedia is the ultimate authority).... I'd be interested in knowing what sort of convoluted reasoning was used to arrive at this conclusion. In the real world it is completely wrong.



H.W.