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Old 03-29-2008, 11:25 AM   #31
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how much capacity do I REALLY have?


My comments in blue. BTW, capitalisation helps when it comes to understanding something.

Quote:
Originally Posted by Knucklez View Post
probably this oven is OK (not sure, eh Knucklez?). your city inspector/permit will tell you if you are safe or not (not in my country...unless you pay). run dedicated breaker to it of appropriate size (he has run out of free breaker spaces). i agree on doing a load calc,.. but in the end, you are left this this practical thought:

if it trips main breaker, see if you were doing something unusual (Unusual? Do you mean using appliances as they would normally be used?). like, had 2 ovens on, vacuuming the house and using electric dryer, and hot-tub on full blast. then you can cut back usage when you are running oven. So, you suggest a house whereby everybody is on "alert" when a breaker trips. I can hear the conversation now;

Mum: Was that you Johnny?
Johnny: Sorry mum. I forgot you were cooking.
<Dad resets breaker because house was in total darkness>
Dad: Kids, turn off your computers while mum cooks dinner.

but if it trips a couple of times and you WERE careful then you'll have to pay for 200A service. If calculated by a "proper" electrician, there will be no need to experience any trips. so if the new panel is same manufacturer, then all your breakers are re-usable. and the oven you already installed is OK as is..

so your only additional cost is panel and supply wires from city to panel. no additional work, so everything to did leading up to this final decision does not have to be redone or anything.

this is how i would approach your situation,
Knucklez

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Old 03-29-2008, 12:03 PM   #32
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Silk, you have totally failed to even vaguely answer the OP's question, as below.

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Originally Posted by analogmusicman View Post
my house has 100A service (built in '79)
I'd like to put an elec. range in the apartment I'm building downstairs.
problem is,I've already got a 220v circuit for OUR range upstairs.
the question is whether the 100A service will handle TWO ranges or will I have to stick a gas range down there? (having a 200A service installed is out of the question
The best & first answer came from Speedy, "Do a load calculation".

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Originally Posted by Silk View Post
In America we use a demand factor of 3VA/ft2 for general lighting and convenience receptacles in a single family dwelling. You have just made my point for me, it is not realistic or accurate, so thank you very much.
Unfortunately for you, I didn’t make any point. You chose to distort what I had said. In reality, the electrical regulatory bodies have analysed “Demand” for many years & as such, have come up with a reasonably accurate way to deal with demand based upon general usage. Your method is pure conjecture.

Quote:
Originally Posted by Silk
As to your "electrical maximum demand calcs", I didn't bother to read it, but we are supposed to use 3VA rule.
Who said “we [the USA] are supposed to use “3VA per square foot”” as a method of determining Maximum Demand? Since you are the only person to have answered, I will not believe you. Not only this but many other methods of determining Maximum Demand can & may be used, your method not being one of them.

Quote:
Originally Posted by Silk
You make my point again, our rules are guesstimates, thank you again
Your (USA) rules are NOT "guesstimates."


Quote:
Originally Posted by Silk
No, I don't believe in diversity, everybody should be just like me, in a perfect world that is.
Now you are being childish.

Quote:
Originally Posted by Silk
Our "rules" are again ESTIMATIONS (3VA/ft2) do you understand that?
Are you sure that they are “estimations”? If so, how were the estimations calculated?

Quote:
Originally Posted by Silk
If you look at the OP the title was "How much capacity do I REALLY have". He wasn't asking for an estimate bases on load calcs
(which you have failed to do).

So far, your info regarding “load calcs” has been incorrect. If you wish to help the OP, why don’t you ask him for info so that YOU can calculate his Maximum Demand. I’m sure that with your infinite wisdom that you’ll do a superb job.
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Old 03-29-2008, 12:23 PM   #33
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Are you sure that they are “estimations”? If so, how were the estimations calculated?

Table 220.55 of the NEC states that: Over 1¾ kW through 8¾ kW. In lieu of the method provided in Column C, it shall be permissible to add the nameplate ratings of all household cooking appliances rated more than 1¾ kW but not more than 8¾ kW and multiply the sum by the demand factors specified in Column A or Column B for the given number of appliances.

I suggested a average of 7Kw for a range which is pretty standard. The demand factor for 2 ranges of equal sizes is 80%. So 7 + 7 = 14 Kw. 14 x .8 = 11.2 Kw.

So if I do a "real load calculation I come up with 11.2 Kw instead of 14 which is what it would "really be" if both ranges were on full blast.

So yes, our calculations are based on what we "guess" that a dwelling will be using at any specific time. We use 80% because we "suspect" that all the burners and the oven won't be on full blast at the same time.

Our calculations are based on estimates that's why we use 80 %, 125%, 75%, 3VA/ft2, ect, ect........................... Can you comprehend?
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Old 03-29-2008, 12:24 PM   #34
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My concern is with the OP and what he's wanting to accomplish. IMO as with others will not say yes until load calc. is done. Load calc. for service entrance takes the guessing and wondering out. He may not need 200, he may only need 150 for his service. You won't know without doing a load calculation.
Going around and turning everything on does not give accurate calc. That was thing and I can let that go but here is what got me.

Quote:
And who really cares if he trips his main breaker, he will learn to tell the kids to turn the stereo off if he is going to use 8 burners and 2 ovens.
This is not in the best interest of homeowner tripping the main repeatedly is where the potential hazard lies.

Quote:
I guess I would like you to explain where the danger comes in, .
The HO had said that the house was built in 79' which makes 29 years old.
The life of the wire itself can last almost a lifetime, BUT the insulation will not. Insulation Breakdown. before that breaker trips, it will heat up for a short period before the trip occurs. The insulation which is old, will start to cook from the inside out in which becomes brittle and flake off exposing the wire. Breakers that trip often may not be as effective. I have had two experiences of this problem. One with an old house and 1 restaurant in the last year.

Doing a load calc. gives the answers that is needed to be sure, it is not guess work.

The homeowner can do whatever he likes, the choice is his to make. I just felt he should hear the potential hazards that can occur.
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Old 03-29-2008, 12:47 PM   #35
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Quote:
Originally Posted by Silk View Post
Are you sure that they are “estimations”? If so, how were the estimations calculated?

Table 220.55 of the NEC states that: Over 1¾ kW through 8¾ kW. In lieu of the method provided in Column C, it shall be permissible to add the nameplate ratings of all household cooking appliances rated more than 1¾ kW but not more than 8¾ kW and multiply the sum by the demand factors specified in Column A or Column B for the given number of appliances.

I suggested a average of 7Kw for a range which is pretty standard. The demand factor for 2 ranges of equal sizes is 80%. So 7 + 7 = 14 Kw. 14 x .8 = 11.2 Kw.

So if I do a "real load calculation I come up with 11.2 Kw instead of 14 which is what it would "really be" if both ranges were on full blast.

So yes, our calculations are based on what we "guess" that a dwelling will be using at any specific time. We use 80% because we "suspect" that all the burners and the oven won't be on full blast at the same time.

Our calculations are based on estimates that's why we use 80 %, 125%, 75%, 3VA/ft2, ect, ect........................... Can you comprehend?
Are you for real????

So bloody what! You did a pathetically easy calculation. This proves/means nothing. Why? The OP asked if he could ADD this range to his existing installation without upgrading anything. Come on "Mr Electrician", tell us (& the OP) if he can add what he wishes to his existing installation with or without upgrading his supply.
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Old 03-29-2008, 01:20 PM   #36
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Maybe there's a language barrier here. My point is that an NEC load calculation is based on estimations, which are only guesses based on averages. You asked me to prove that the calcs were a guess, and I did!!!!!
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Old 03-29-2008, 01:28 PM   #37
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Originally Posted by elkangorito View Post
Are you for real????

So bloody what! You did a pathetically easy calculation. This proves/means nothing. .

Thank you for agreeing with me again. That's my point, it is a pathetic calculation, all bases on averages.

Nice to see you're starting to see straight and think like me.
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Old 03-29-2008, 02:26 PM   #38
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Quote:
Originally Posted by elkangorito View Post
Are you for real????

Come on "Mr Electrician", tell us (& the OP) if he can add what he wishes to his existing installation with or without upgrading his supply.

I already told him how to figure out his "real load", not one based on guesses and averages. Are you a little slow today?
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Old 03-29-2008, 08:12 PM   #39
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Please try and be civil in here, and less rude.

Thanks Ron
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Old 03-31-2008, 02:22 PM   #40
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Somehow this thread turned left when it should have turned right.

Backing up to the beginning of this thread. The op asked a simple question can he add a second electric range to his apartment he is building downstairs.

My first response would have been ....apartment?..ie...your changing from a single family dwelling to a multifamily dwelling..your going to rent out living area?

There are a whole list of departments both city county and state that need notification of you doing this....along with all the other issues. Now if we're talking building a mother in laws quarters and not renting to the general public then that is another road.

Now that being said and all things being equal...Speedy had the correct answer... a load calculation would be required for the apartment.. separate from the dwelling load. This is the only acceptable requirement by the codes department.

It was mentioned that for "fun" you could use a clamp on meter at the service equipment while turning on everything in the house and get the "real load". I respectfully submit... that is all that was intended with that statement.....for fun.

Then we turned 'left' when the sign said 'turn right'.

While traveling down the wrong road (the one that went left) the terms "guess" and "estimates" were used to describe Art.220. Bear in mind these words are never mentioned in Art. 220. The use of these terms were an individuals opinion that Art. 220 was about "guesses" and estimates". I would suggest a thorough research into how the article came to be and how all those so called "guess tables" and "estimates" for load factors giving us "diversity consideration" for feeders and services and branch circuits came about. HINT: they were not someones guesswork. Table 220.55 being referred to as a table of estimates and guesses is a bit of a rather enormous stretch of the truth. I don't believe I have ever seen any documentation anywhere that the load factor tables in Art. 220 are guesses. Again an individuals interpretation.

BTW 3VA/ft2 is not a guess.

7kw is not any standard for a range that I have ever heard of in my career. I would have to ask for some place for me to see where that is written.

Please tell me where the term "real load" enters into anything about the acceptable requirement for calculating the addition of a second range to a dwelling. I respectfully submit your inspector would look cross eyed at you if you wrote your "real load" down at the top of your load calculation being all that would be required...he might say something like "did you do that for fun"?

I only say all this out of respect for the facts and the proper respect for the NEC and all that went into making that book of minimum safety standards.

It ruffles my feathers a bit when I see it butchered while we were on the road that went left.

Stubbie

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Old 03-31-2008, 03:18 PM   #41
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Of course it's an estimate. 3000 VA for a kitchen, 1500 VA for a laundry. Is that the exact load for every kitchen and laundry? Of course not, it would be ludicris to suggest so! The NEC is Estimating that that would be sufficient for most dwellings. My definition of an estimate is the same as that of a hypothesis, which is only an educated guess.
The OP asked what capacity he really had. The only way to determine that is to find out what his specific load is. That cannot be done using general formulas that can apply to every dwelling.
That being said, I did not say that this is how to "do it by code", but will his service handle it? I still say probably yes based on my educated guess having seen this in countless homes over the years.
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Old 03-31-2008, 03:21 PM   #42
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Oh, and by the way, you can "respect" the NEC all you want, but they lost all my respect when they let NEMA push their AFCI's through.
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Old 03-31-2008, 05:59 PM   #43
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Quote:
The OP asked what capacity he really had. The only way to determine that is to find out what his specific load is. That cannot be done using general formulas that can apply to every dwelling.
You need to lower your defenses some. I was simply trying to engage you in a civil conversation about Art. 220 not being guess and estimate. However you attitude tells me that your ego will not allow you to learn. Is this because you have some personnel damage done to you by the passing of afci language in the new 2008 code?

In my years in the trade I have never seen an electrician walk into a home and turn "everything on" including those things that have maximums to get a "real load" to determine whether a service upgrade is required or anything else for that matter. Please explain why you would approach turning on every light and maximums on appliances and all plug in equipment and all fixed equipment in ones home to get a "real load" that would be useful for anything? I took your earlier comment to mean that you did this for fun but were not serious. Now it seems that you do think this is how it should be done to determine a dwellings real load.

I was merely saying you did this for "fun" , it would not be something you would actually do at someones home during a service call if you were considering a service upgrade. To do a specific load calculation would be rather a one time issue don't you think? Without load diversification being considered you would severely handicap a proper service sizing.

How did the cmp arrive at 3VA/ft2 or table 220.55.....by guessing?

I'm sorry you no longer have respect for the NEC. That is a shame. All because of AFCI. That idea they had about gfci must have really frosted you also. Of course your local codes department has every right to not adopt the afci language. So it really isn't that big of a threat. Adoption of afci will come through the evolution of the product and how it affects the probability of home fires through the data generated by the NFPA. If that data shows an increase in fires or no significant increase in fires it is likely afci will take a long time to be adopted by the local codes authorities.

Without knowledge of how the 220 article came to be your short changing all the hard work that went into those load factors by calling them estimates and guesswork.

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Old 03-31-2008, 06:29 PM   #44
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As an electrician, I would do a load calc. If I was doing this for pay I would do it by the book (NEC) because I would have to pull a permit. As to answering the OP's question about if his service would handle it, I said yes, probably. This is a DIY site, if this non-tradesman is going to install a range himself, which is what he is planning on doing otherwise he would have called an electrician, I would rather have him put in an electric range than run a gas line.
I have seen many second ranges in basements in 100 amp homes without any problems, I am very scared of homeowners running gas lines.

As to the "guess" "estimation" statements. I like to refer to the 25 ohms to ground section for ground rods. If one rod doesn't meet the 25 ohms requirement, then the NEC says to add another one. What happens when the second ground rod doesn't meet the 25 ohm requirement? The answer is nothing, the NEC could care less. They just say "what the hell, at least yo tried". Does that seem very technical to you? Not to me. It seems like they just threw a number out there and if yo can't meet it, then it doesn't really matter.
There are alot of zealots out there, religious, union vs nonunion, and there are NEC zealots also. I am just not one of them. I have spent many years reading the code and there are too many contridictions in there to get to worked up about it's significance for me.
Sorry if I offended.
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Old 03-31-2008, 06:43 PM   #45
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No offense taken

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There are alot of zealots out there, religious, union vs nonunion, and there are NEC zealots also
.

Flash...I agree with you!! I hate rubber stamps as much as you.

Remember though we have the codes proposal systems as our check and balance. As for contradictions yep probably a few but it has been my experience that what one thinks is a contradiction generally turns out to be an unforseen tie in with another application. the NEC will always be a work in progress as will the IEC.

What I really think happened here is a simple comment being carried to the point of being a ridiculous overreaction. Then we got into the let me prove I know more than you wagon.

Have a good day Silk.

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