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1959 NEC


Robert Jones
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Thanks Douglas,

The buyers "uncle", has come out to the home after closing and made some statements to my buyers such as; 30 amp breaker servicing the range, and a statement of "it appears to be 14 gauge wire servicing the bedrooms with oversized breakers". A "bare neutral conductor". Fairly minimal stuff with the exception of the bedrooms. All original stuff from 1961. I get the feeling I am beeing walked into something and just want to have some facts straight. While I agree with the 30amp/range service should be 40-50amp, I am curious as to the standard in 1961 for that setup.

Thanks again.

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While I agree with the 30amp/range service should be 40-50amp, I am curious as to the standard in 1961 for that setup.

If it's not tripping, the circuit is most likely is not overloaded.

But....... current standards indicate the need for a min. 40 amp breaker for an electrical range. (based on memory-- you could check NEC table 220.55)

What is the nameplate rating on the range?

Was the panel, breaker, and range original to the house?

Here's a good article to read up on: http://www.ecmag.com/?fa=article&articleID=9833

Sorry, no real help for 1961 standards. I just got home and figured I'd post something.

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Thanks Douglas,

The buyers "uncle", has come out to the home after closing and made some statements to my buyers such as; 30 amp breaker servicing the range, and a statement of "it appears to be 14 gauge wire servicing the bedrooms with oversized breakers". A "bare neutral conductor". Fairly minimal stuff with the exception of the bedrooms. All original stuff from 1961. I get the feeling I am beeing walked into something and just want to have some facts straight. While I agree with the 30amp/range service should be 40-50amp, I am curious as to the standard in 1961 for that setup.

Thanks again.

The 1959 NEC would have required a minimum 40-amp circuit for a range. (Table 220-5) Now if it were a wall mounted oven or cooktop, it might have been ok ot use a 30-amp circuit. But that should have been re-evaluated and upgraded when the range was installed. No matter what, a 30-amp circuit feeding a normal-size range today is not right.

The 1959 NEC required #14 copper cables to have 15-amp overcurrent protection -- in most cases, the same as today. (Table 210-25)

I don't understand the bare neutral comment. If you're talking about a bare neutral service conductor, that was ok then and its ok now -- depending on certain conditions. (230-40 in 1959) (230-41 in 2008)

I'd be interested to know if Douglas has any other insights into the '59 requirements.

- Jim Katen, Oregon

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My house was built in 1960 and I have an electric cooktop (1985 jenn-air), double oven in the wall (looks 15-25 years old) and an electric stove in the basement in a fallout room all on a 50 amp breaker. Never had a single problem with it tripping, and have had all but the basement stove on at the same time. Wether this is right or not I do not know but just thought I would toss that out there seeing as how this was the same time period.

Matt

P.S.: When I bought my house 2 years ago, We had a home inspection that didn't mention alot of things but said the house was sound and he'd move in tonight.

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I'm not sure I understand the concern on the range circuit. The way I'm reading it, you only need 8AWG for a range circuit that is 8.75kW or greater. If the nameplate of the range is less than that, you need only match the load. I'm looking at 210-10(b) in the 1959 NEC, and 210.19(A)(3) in the 2008 NEC.

In the 1959 NEC, the fine print note to 220-4(i) recommends you use table 220-5 for the calculation on the feeder load even if you are using a smaller range, just in case you later replace it with a larger one. However, that has to do with the feeder load calculation, not the branch circuit size. Likewise, note 5 to table 220-5 says you "may" use table 220-5 to calculate the load for a single range. What that means is you can apply the demand factors of 220-5 for ranges in the 8 to 12 kW size range. Note 5 also says to use the nameplate rating for single wall-mounted ovens or counter-mounted cooking units.

I don't think a range qualifies as a continuous load, therefore the circuit ampacity need only be 100% (not 125%) of the load. If the load is 7.2kW or less, a 30-amp circuit should be OK. 30Ax240V=7.2kW. The same is true today as it was in 1959.

Douglas Hansen

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I'm not sure I understand the concern on the range circuit. The way I'm reading it, you only need 8AWG for a range circuit that is 8.75kW or greater. If the nameplate of the range is less than that, you need only match the load. I'm looking at 210-10(b) in the 1959 NEC, and 210.19(A)(3) in the 2008 NEC.

In the 1959 NEC, the fine print note to 220-4(i) recommends you use table 220-5 for the calculation on the feeder load even if you are using a smaller range, just in case you later replace it with a larger one. However, that has to do with the feeder load calculation, not the branch circuit size. Likewise, note 5 to table 220-5 says you "may" use table 220-5 to calculate the load for a single range. What that means is you can apply the demand factors of 220-5 for ranges in the 8 to 12 kW size range. Note 5 also says to use the nameplate rating for single wall-mounted ovens or counter-mounted cooking units.

I don't think a range qualifies as a continuous load, therefore the circuit ampacity need only be 100% (not 125%) of the load. If the load is 7.2kW or less, a 30-amp circuit should be OK. 30Ax240V=7.2kW. The same is true today as it was in 1959.

Douglas Hansen

Agreed on all points. Except that most ranges I see, even 50-year old ones, are at least 8kw. Wouldn't a 7.2 kw range be rather small?

- Jim Katen, Oregon

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Agreed Jim. Even though these things are more efficient and generally lower wattage today than they were 50 years ago, most will exceed 7.2kW. Freestanding electric ranges of that era typically came with a 50-amp NEMA plug.

It's interesting to me that ranges have such a high rating, where the combined rating of an individual counter-mounted cooktop and a wall oven might not add up to anything close to that amount, even with greater cooking capacity.

I think Brandon nailed it though - what matters is the rating on this particular one. It's not the sort of information I expect most home inspectors look at. When I was a home inspector, I bought one where the homeowner had replaced a single oven with a double oven on a 30-amp circuit, and the circuit couldn't handle both being on at the same time. It taught me to look at the nameplates.

Douglas Hansen

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I'd suggest that modern electric resistance heating elements reach higher temperatures while retaining adequate mechanical strength than older elements. Higher temperatures result in a higher ratio of radiant to convective heat transfer. With more of the developed heat transmitted to the load, less input is required. It might not have any advantage on a water heater where the element is immersed in the medium and all energy is transmitted to the water but on a stove or oven, design can influence how much energy is lost to the surrounding air.

Just my opinion.

Marc

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