Service -entrance conductors OCP

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travis301

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My question is this,Im looking at a job that has a 320a meter base on the side of a metal garage. Out of the meter base there is a 200a feed going to a QO panel with a main breaker about 10 feet away inside the garage.The 200a feed is coming off of 1 set of the double barrel lugs.I dont have a problem with this because the tap rule should cover this. The problem is,the owner wants to run a 200a feed to his new house which is about 200 feet away directly off of the double barrel lugs with no OCP until he hits the the main in his new house. IMO,the new SEC's would not be covered by a tap rule and would be a violation. In my mind I am thinking a 200a fused disconnect or a set of fuses off to the side of the meter base would satisfy the requirements. I have strolled thru Article 230 and cannot find any other way this could be done. The owner is wanting a bid from me and I would like the job,but I am afaid my competition will look past this.This is in a rural environment so there isnt a AHJ to discuss it with.Any thoughts?
 
I have seen homes metered at the pole a couple hundred feet from the house. The feed from the pole to the house does not have any protection. Also you can run the SE around the house unprotected to the panel as long as it is limited once it comes inside.
 
I would say the the SE's on a situation like that would be protected if the service from the power company was fused at 200a and you was running to a 200a panel. What I dont agree with is that this service has a potential of a minimum of 320a (probably more depending on power company fusing) and I am going to put 3/0 wire on it unprotected for 200 feet. It doesnt seem right to me.
 
NEC 230.40 exception 3 allows multiple sets of service conductors to a single family dwelling and a separate structure. I don't see anything else that doesn't let you do this. This isn't must different than 6 houses all tapped off a 100 KVA transformer. SEC's are usually not fused at the source, it is the main disconnect that provides protection. I wouldn't want to have a fault on a 3/0 wire whether its on a 10KVA or 100 KVA transformer.

The only thing I can't determine is what size GEC you must use at each building. Table 250.66 says what to do if you were using exception 2 to 230.40, but you're using exception 3. To be compliant, you may need to use the larger size of the most upstream set of service entrance conductors.
 
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Forgive me if I fail to grasp this but you have a 320/400 amp single phase service.One panel is within I assume the allowed distance as by required by the poco and AHJ.Now the retro will have a second panel 200 ft away in a seperate structure, without a disc.as per homeowner.

This brings up an interesting point.The first point of entry rule. To me this has aways been within the same structure.To leave that structure would require a disc.I`d bid a disc. and a 4 wire feed,since the new house panel would be a sub panel.Also doesn`t the second structure require a disc. on it ???Just woke up no coffee so I`m not going to search the bible for a referance.
 
The conductors that never enter a structure, and run over to the house are of little concern. The ones that run into the garage for 10' (probably longer, conductor wise?) are of concern. Around here, we consider the point "nearest the entry of service conductors" to be immediate.

What you describe is NEC compliant, provided the AHJ agrees the 10' conductors are "nearest", and the POCO agrees with the routing of the service conductors to the second structure.

You can run the service conductors in laps around the house, if you'd like, there's no restriction on them. Just be sure they're identified as required in 300.5(D)(3). :)
 
suemarkp said:
The only thing I can't determine is what size GEC you must use at each building. Table 250.66 says what to do if you were using exception 2 to 230.40, but you're using exception 3. To be compliant, you may need to use the larger size of the most upstream set of service entrance conductors.
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What do you think about this:

The conductors to the line side of the meter are service conductors.
The conductors on the load side of the meter are service entrance conductors.
Table 250.66 is written in regards to service entrance conductors, so the conductors for the garage could be used for sizing the GEC for the garage, and the house for the house.

That's the easiest way of thinking of it in my book, but I think that's ultimately up to the AHJ, isn't it? Or is there a hard and fast answer to this problem?
 
travis301 said:
I would say the the SE's on a situation like that would be protected if the service from the power company was fused at 200a and you was running to a 200a panel. What I dont agree with is that this service has a potential of a minimum of 320a (probably more depending on power company fusing) and I am going to put 3/0 wire on it unprotected for 200 feet. It doesnt seem right to me.
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I don't believe we could take any credit for the POCO's fusing, in any case. I'm thinking of the scope of the NEC (90.2?), and 230.90. Service conductors are just assumed to be unlimited conductors that must be kept on a short leash, IMO.
 
Well what about this section?

230.72 Grouping of Disconnects.
(A) General. The two to six disconnects as permitted in 230.71 shall be grouped. Each disconnect shall be marked to indicate the load served.

I would think that both 200 amp main breakers would have to be located at the same place instead of one over here and the other over there.
What do you think?
 
I don't see a need to have the disconencts grouped for this application. If the code requires grouping, then there is no way to use Exception #3 to 230.40.
Don
 
jwelectric said:
Well what about this section?

230.72 Grouping of Disconnects.
(A) General. The two to six disconnects as permitted in 230.71 shall be grouped. Each disconnect shall be marked to indicate the load served.

I would think that both 200 amp main breakers would have to be located at the same place instead of one over here and the other over there.
What do you think?
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230.71 and 230.72 are difficult to resolve, as they seem to conflict or are redundant. 230.71 allows 2 to 6 disconects per SET of SEC's. It says they must be grouped with not more than 6 in one location. But 230.72 says the 2 to 6 disconnects in 230.71 must be grouped. Which 2 to 6 is it talking about -- the total service (how could you have 2 to 6 per set if that is the case) or just within each set that 230.71 already said to group???
 
I also agree with Mike that the service disconnects need to be grouped with 230.72. Mark I never see in 230.71 were it says they must be grouped, only in 230.72 and that is refering to 230.71 but I have been wrong before.
 
don_resqcapt19 said:
I don't see a need to have the disconencts grouped for this application. If the code requires grouping, then there is no way to use Exception #3 to 230.40.
Don
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Maybe I am reading the original post wrong. The way I am seeing this installation is the two panels are on ONE building and are being fed with conductors rated at 200 amps.

If this is indeed two separate buildings and each is supplied with conductors sized no smaller than the calculated load and the main overcurrent device is either on the outside or inside nearest the point of entry I see no problem as long as the conductors supplying the second building do not pass through the first.
 
In my area, it is quite common to see an overhead service running to a pole with a meter socket and disconnect below. Then the feeders are run underground to the building to be served sometimes a very long distance. I'm wondering why the disconnect is necessary before the conductors enter the building. Why not eliminate the disconnect at the pole and run the service entrance conductors to the building and put the disconnect there which would be much more convenient for servicing. Either way only three condctors are needed since there would be no parallel path concerns so the cost of the wire isn't a factor but it just seems to me that the pole mounted disconnect is kind of un necessary. Forgive me if I'm straying from the original topic but this has been a concern for a long time.
 
don_resqcapt19 said:
I don't see a need to have the disconencts grouped for this application. If the code requires grouping, then there is no way to use Exception #3 to 230.40.
Don
Click to expand...

Don I agree. I was wrong with my last post in this situation.

John
 
Well after reading the posts and going back thru 230, I can see both sides of the fence. If you use 230.40 exc #3, does it mean that you have to use 2 disconnects in a common place before taking the SEC's to there respective panels,in order to satisfy 230.72?
 
Ttravis,
If you use 230.40 exc #3, does it mean that you have to use 2 disconnects in a common place before taking the SEC's to there respective panels,in order to satisfy 230.72?
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Service conductors do not exist on the load side of the disconnect...they are feeder conductors.
Don
 
I think I see the light now Don. If the disconnects mentioned in 230.72 where for one set of SEC's going to one structure,they shall all be grouped together at that structure. But,since I will in effect have 2 sets of SEC's going to 2 different structures, 230.72 does not apply. Does everyone agree?
 
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