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 DIY Chatroom Home Improvement Forum how much capacity do I REALLY have?
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03-29-2008, 10:25 AM   #31
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My comments in blue. BTW, capitalisation helps when it comes to understanding something.

Quote:

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03-29-2008, 11:03 AM   #32
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Silk, you have totally failed to even vaguely answer the OP's question, as below.

Quote:
 Originally Posted by analogmusicman 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".

Quote:
 Originally Posted by Silk 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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Last edited by elkangorito; 03-29-2008 at 11:18 AM.

 03-29-2008, 11:23 AM #33 electrician   Join Date: Feb 2008 Posts: 326 Rewards Points: 250 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?

03-29-2008, 11:24 AM   #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.

03-29-2008, 11:47 AM   #35
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Quote:
 Originally Posted by Silk 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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 03-29-2008, 12:20 PM #36 electrician   Join Date: Feb 2008 Posts: 326 Rewards Points: 250 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!!!!! Game, Set and Match
03-29-2008, 12:28 PM   #37
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Quote:
 Originally Posted by elkangorito 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.

03-29-2008, 01:26 PM   #38
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Quote:
 Originally Posted by elkangorito 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?

 03-29-2008, 07:12 PM #39 Journeyman Plumber     Join Date: Jun 2006 Location: Eugene, Oregon Posts: 1,994 Rewards Points: 1,000 Please try and be civil in here, and less rude. Thanks Ron __________________ Fix it right the first time, so you won't have to fix it a 2nd time. 2008 Oregon Specialty Plumbing Codes
 03-31-2008, 02:18 PM #41 electrician   Join Date: Feb 2008 Posts: 326 Rewards Points: 250 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.
 03-31-2008, 02:21 PM #42 electrician   Join Date: Feb 2008 Posts: 326 Rewards Points: 250 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.
03-31-2008, 04:59 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.

Last edited by Stubbie; 03-31-2008 at 10:23 PM.

 03-31-2008, 05:29 PM #44 electrician   Join Date: Feb 2008 Posts: 326 Rewards Points: 250 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.
03-31-2008, 05:43 PM   #45

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No offense taken

Quote:
 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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