Additional disconnects required?

[kbsparky]

Here is a real scenario I've encountered:

A new house, with an outside meter combination disconnect box located 25 feet away from the house.

From there, an underground conduit travels to the building, and under the basement slab to a point in the cellar where a transfer switch and load center are located.

On the opposite end of the house, there is a 20 kW standby generator, which has its own 100 Amp breaker/disconnect built-in. It also has an underground conduit that travels under a concrete slab to the same transfer switch in the cellar.

Since both disconnects are located outside, and within sight of the house, is there any requirement for additional disconnecting means at the transfer switch in the cellar?

I have attached a drawing outlining the basic layout.

 

[frank everingham]

a disconnect switch is required at the transfer switch. art 225.31@225.32 allow up to up to 6 mains at this location. the main disconnect at the t- switch is to be grounded as required in article 250.50@ 250.52. the outside meter and disconnect also require grounding as required by 250.50. if none of the electrodes in 250.52 are available at the outside disconnect, install 2 ground rods. 250.32b requires a 4 wire system from the outside disconnect to
the inside disconnect . the generator is just a piece of equipment.

 

[kbsparky]

a disconnect switch is required at the transfer switch. art 225.31@225.32 allow up to up to 6 mains at this location....

I read sections 225.31 and 225.32 before posting this.

I believe that the outside disconnect at the meter provides the desired protection of 225.31, since it is outside the building and within sight of the structure as defined in article 100. Ditto for the disconnect at the generator set.

For those who advocate that a "Service rated" transfer switch be provided, I ask you to consider the following:

1) The neutral can NOT be bonded at the transfer switch, since it is bonded outside at the meter/main disconnect. A 4-wire feeder is utilized in this instance.
2) A transfer switch does NOT have any means to disconnect the alternate source power coming from the generator set, whether it be "service rated" or not.
3) The explanatory notes (Exhibit 225.6) in the NEC Handbook recognize the outside disconnecting means at the generator as adequate to satisfy the requirements of articles 225, 445, and 702. Why would an outside disconnect for the generator be adequate, but not for the utility feed? We are dealing with the exact same thing on both feeders.

As for the lecturing on grounding issues, that was not called for here. This thread is asking about opinions on disconnecting requirements.

 

[qcroanoke]

Is the disconnect at the generator in compliance with 225.36 as required by 702.11?

 

[augie47]

AS far as the generator is concerned, IMO, the only way to omit a disconnect in the house would be IF the generator meets the requirement of 702.11 (none I have seen do).
As far as the service is concerned, as I read 225.32, I see a requirement for a disconnect inside ("nearest the point of entrance")

 

[qcroanoke]

As far as the service is concerned, as I read 225.32, I see a requirement for a disconnect inside ("nearest the point of entrance")

But since it has a "disconnect" ( I assume this is actually overcurrent and short circuit protection and therefore the service) outside the house isn't it now a feeder? And it is under the slab so it is not passing through the house.

 

[augie47]

It is a feeder, thus the reference to Art 225 rather than Art 230. As I read 225.32, a disconnectd is needed where the feeder enters the house.

 

[kbsparky]

It is a feeder, thus the reference to Art 225 rather than Art 230. As I read 225.32, a disconnectd is needed where the feeder enters the house.

But they also allow it to be "outside" as well?

What about exception #1?

 

[qcroanoke]

It is a feeder, thus the reference to Art 225 rather than Art 230. As I read 225.32, a disconnectd is needed where the feeder enters the house.

Ok, got it.
Missed the fact that 225 was outside branch circuits and feeders.

 

[kbsparky]

AS far as the generator is concerned, IMO, the only way to omit a disconnect in the house would be IF the generator meets the requirement of 702.11 (none I have seen do)....

Since we are not dealing with a "portable" generator, section 702.11 does not apply here.

Section 702.12 indicates that since there is a disconnecting means at the outdoor generator, and its within sight (as stated earlier), then an additional disconnecting means shall not be required.

My questioning here stems from the fact that I can have a transfer switch in the middle of the cellar, with 2 feeders coming into it, one from each end of the house. There are some folks who are telling me that I must have a disconnecting means on one of them (even though there IS one outside, and within sight), but its not required on the other one? This makes no sense at all!

 

[augie47]

But they also allow it to be "outside" as well?

What about exception #1?

All I'm doing is giving an opinion
Your AHJ may buy it. I find it hard to imagine a residence with "documented safe switching procedures are established and the in stallion is monitored by qualified individuals"

Since we are not dealing with a "portable" generator, section 702.11 does not apply here.

We were caught in a "which Code" scenario. I was referencing the '08 which basically is 702.12 in '11.

Section 702.12 indicates that since there is a disconnecting means at the outdoor generator, and its within sight (as stated earlier), then an additional disconnecting means shall not be required.

BUT, you need to look at the entire wording...."The disconnect shall meet 225.36"
I have yet to find a residential generator where the on-board disconnect is identified as "suitable for service equipment"

My questioning here stems from the fact that I can have a transfer switch in the middle of the cellar, with 2 feeders coming into it, one from each end of the house. There are some folks who are telling me that I must have a disconnecting means on one of them (even though there IS one outside, and within sight), but its not required on the other one? This makes no sense at all!

As noted I think you need one for both. From a practical standpoint for safety of those working on the T/S.
I feel like I am getting into a spitting contest which is not my intention. As I say MY OPINION is two disconnects at the T/S per the sections I quoted. The important opinion will be your AHJs.

 

[Gregg Harris]

Since we are not dealing with a "portable" generator, section 702.11 does not apply here.

Section 702.12 indicates that since there is a disconnecting means at the outdoor generator, and its within sight (as stated earlier), then an additional disconnecting means shall not be required.

My questioning here stems from the fact that I can have a transfer switch in the middle of the cellar, with 2 feeders coming into it, one from each end of the house. There are some folks who are telling me that I must have a disconnecting means on one of them (even though there IS one outside, and within sight), but its not required on the other one? This makes no sense at all!

702.11 does apply to your situation it is under Artical 702 Optional Standby System.

702.1 Scope The provisions of this article apply to the instalation and opperation of optional standby systems.

The systems covered by this article consist of permanently installed in there entirety,etc so as long as the disconect is Sutible for Service Equipment it would be compliant and no disconect inside would be needed.

 

[kbsparky]

702.11 does apply to your situation it is under Artical 702 Optional Standby System....

I don't THINK SO!

702.11 is specifically for PORTABLE generators. This installation does NOT utilize a PORTABLE unit.

 

[kbsparky]

It is a feeder, thus the reference to Art 225 rather than Art 230. As I read 225.32, a disconnectd is needed where the feeder enters the house.

Do you think that this would be compliant?

 

[kwired]

The service disconnect in this case is at the pole/pedestal. The line to the house is a feeder. The house still needs a disconnect rated for use as service equipment, either outside or inside "nearest the point of entry"

NEC does not specify if a disconnect outside and 25 feet away yet within sight is acceptable for this purpose.

If you were feeding a garage 25 feet from the house and had disconnect on the house and no disconnect in or on the garage would you say the one on the house is acceptable to be the main disconnect for the garage - it is essentially the same installation as in this thread. Most would say no there needs to be a disconnect on the garage. If I were to attempt that I would want the OK from the AHJ before doing so.

 

[kbsparky]

My house is like that, with a disconnect on the house, 25 feet away from a garage with no additional disconnect in there.

Like you said, it's "outside" and "within sight" of the garage, and the AHJ did not require anything further.

 

[Gregg Harris]

I don't THINK SO!

702.11 is specifically for PORTABLE generators. This installation does NOT utilize a PORTABLE unit.

702.11 was 2008 the same for 2011 is 702.12

As long as the transfer switch has a UL 1008 it would be compliant

 

[augie47]

Do you think that this would be compliant?

I would only think so IF the generator disconnect met 702.12 & 225.36 (which I doubt)

Personally I would prefer the Art 225 required disconnect at the transfer switch but "at point of entry" suffices.

 

[copper chopper]

hard to say

hard to say

I look at 230.6-1 and 230.70-a-1 that tells me this is legal maybe, this article states that the disconnect must be in a readily accessable location. also the load center mentioned is there a main in it? but if I looked at it I would say you need to be able to disconnect each power source going to the transfer switch, it just makes sense..how ever 702.5 says to goto artilce 705= 705.20 and 705.21 i think makes this not legal..

 

[kbsparky]

Both the outside disconnects are in readily accessible within sight locations. They are not at the same location, however.

The one thing I wanted to point out was the alternate proposed location of the incoming utility feed disconnect: One scenario has the disconnect box on the corner of the house; the other one is 25 feet away, but within sight of the house. I maintain that there is LITTLE OR NO DIFFERENCE in the safety of either of these scenarios. But does the Code recognize that?

As for the load center, it does have a main breaker, so that should not be an issue.