What you might be missing is that that requirement relates to the rating of the disconnecting means. The amount of power you must supply to the building is a different matter entirely.I would have said 100 amps right off the bat but now since bob answered that way im not sure what im missing
When the NEC was changed to increase the size of the service disconnect, it was intended to require a minimum service size of 100 amps.
230.42 Minimum Size and Rating.
(B) Specific Installations. In addition to the requirements
of 230.42(A), the minimum ampacity for ungrounded conductors
for specific installations shall not be less than the
rating of the service disconnecting means specified in
230.79(A) through (D).
230.79
Oh I get it now the argument is going to be a single disconnect only has to be rated for a 100 amps, A 100 amp service doesn?t need to be installed just a disconnect switch with a 100 amp 3 wire rating. So I guess then a two wire service can be installed as long as there is provision for a three wire service. So I guess they missed it on both accounts.
Even though the reference already handled min. size based on calculated load and if this doesn?t mean a min of a 100 amp service all this talk about 100 amp 3wire is meaningless verbiage.
I guess this is what happens to any document when you do not have a hidtoric reference to what was the meaning of the words being written. or why they were written Even our constitution is suffering the same problem.
someone once said they understood the letter of the law but not the spirit off the law.
It is interesting that if we take that literally it seems to preclude using Table 310.15(B)(6).
So we are required to have a 100 amp disconnecting means, but if we only have 30 amps of calculated load can we have a 100 amp breaker as the service disconnect and supply it with 10 AWG copper service entrance conductors, or even 8 or 6 AWG?
Even if you can prove that is alright, good luck convincing most inspectors as well as many others that it is acceptable.
So ... let's see if I get this right ...
230.72 says a house needs a 100-amp disconnect, and 230.42 says I need to run 100-amp wires (or larger) to it.
That sounds an awful lot like requiring a 100-amp service as a minimum. We really have no way to limit / control what the PoCo can deliver to those wires.
Sure would be more clear if the code simply said "houses get at least 100-amps."
You make a very good point here. Just based on the fact that you and I agree so often :roll: , I looked for the "hidden language" in the code (i.e., something buried in an explicit Exception, or a sentence phrased as "except as noted . . . ," or a cross reference to another article) that would allow the two articles to coexist (i.e., so that the one does not preclude the other). I could not find it. The best I can offer, and I am not at all confident in this conjecture, starts with the notion that Table 310.15(B)(6) {NEC 2008} is not an ampacity table. The associated text says essentially, "Under these circumstances, you can use this wire size." It does not say, "Under these circumstances, this wire size has the following ampacity." If it did, then the apparent conflict between 230.42(B) and Table 310.15(B)(6) would vanish. Since it doesn't speak of ampacity, we are left to infer that it overrides the requirement in 230.42(B) by simply saying, "You can use this wire size."It is interesting that if we take that literally it seems to preclude using Table 310.15(B)(6).
So ... let's see if I get this right ...
230.72 says a house needs a 100-amp disconnect, and 230.42 says I need to run 100-amp wires (or larger) to it.
That sounds an awful lot like requiring a 100-amp service as a minimum. We really have no way to limit / control what the PoCo can deliver to those wires.
What is the smallest residential service you can install on a sigle family dwelling legally.
Thank You
Why would anyone want to install a service rated at less than 100 amps on an actuall residence anywhere in the US? ( gas appliances or not).