230.72 Grouping of Disconnects

[jaggedben]

What about the scenario that I alluded to earlier. On, say, a 400A service you put a SUSE fused disconnect with 600A fuses, followed by an "immediately adjacent" SUSE 400A enclosed circuit breaker as the service overcurrent device.

Not sure why you'd do that, maybe the 400A fuses are out of stock or would cause some other problem.

I think I agree with Elect117.

In this case I'd say that unless the first disconnect qualifies as an 'Emergency Disconnect' or 'Meter Disconnect' or some such, then you don't get out of calling it the service disconnect. So your service conductors would have to be protected by the 600A fuses.

 

[wwhitney]

Service conductor stops at the service disconnecting means.

Well, that raises several issues, see post #5. That definition needs to be changed from "service disconnecting means" to "service equipment."

Otherwise, the allowance of 230.91 is never useable, as if the service conductors stop at the service disconnecting means, an overcurrent device immediately adjacent to the service disconnecting means could never be "in series with" the service conductors. The conductor between the service disconnect and the service overcurrent device had better be service conductors.

The conductors after the switch would be a feeder. "All circuit conductors between the service equipment, the source of a separately derived system, or other power supply source and the final branch-circuit overcurrent device. (CMP-10)"

Right, well in my framing, the 400A breaker is the service overcurrent device and hence service equipment. So the conductors upstream of it would not be feeders.

I mean, suppose the disconnect could take something we could call a "cable limiter" which doesn't provide overcurrent protection but does provide a withstand rating in excess of 10 kA. Then all would fine with the scenario I described? I don't see how expanding the capabilities of that device to provide some unnecessary additional overload protection at a higher than sufficient level suddenly can make the install non-compliant. Certainly it in no way makes it less safe.

Cheers, Wayne

 

[Elect117]

I don't want to confuse acceptable line side connections (emergency disconnect) and service conductors / service equipment.

The OP tried to install a disconnect as both but did not meet the requirements of service protection.

Lets say you wanted to install a meter center with 6 service main breakers AND and emergency disconnect. Well, you could. The issue here is the OP has two services that he has made into one. If they were separate services or separate sets of service entrance conductors (service drop to service disconnect) he would have no code issues.

The code issue with wwhitney's example is that the first disconnect is the service disconnect and could also act as the emergency disconnect.

Now, if we really wanted to get into the weeds on it, you could argue that there is no maximum number of disconnects that could be present so long as there is no more than 6 per service and one for each additional permissible supply side connection. And as long as the service is protected by 230.90 then everything is okay. Not to mention some of the disconnects may not even need to be grouped.

The adding of the emergency disconnect created such a difficult distinction between a line side connection and service disconnect.

 

[wwhitney]

I don't want to confuse acceptable line side connections (emergency disconnect) and service conductors / service equipment.

I think you just did by bringing it up. : - )

I don't think emergency disconnects have anything to do with this discussion. 230.85 covers one and two family dwellings (the text incorrectly uses the term dwelling units, but delete the word "units"), but with 8 meters, this is not a one or two family dwelling.

Cheers, Wayne

 

[jaggedben]

I don't think emergency disconnects have anything to do with this discussion. 230.85 covers one and two family dwellings (the text incorrectly uses the term dwelling units, but delete the word "units"), but with 8 meters, this is not a one or two family dwelling.

We were speaking to your hypothetical in post #17, and saying that for the general case, only such a thing as an Emergency Disconnect or Meter Disconnect could get you out of considering the first disconnect to be the Service Disconnecting Means.

It does seem possible, if not necessarily likely, that the unfused disconnect in the OP could be a 'Meter Disconnect'.

 

[Elect117]

I think you just did by bringing it up. : - )

I don't think emergency disconnects have anything to do with this discussion. 230.85 covers one and two family dwellings (the text incorrectly uses the term dwelling units, but delete the word "units"), but with 8 meters, this is not a one or two family dwelling.

Cheers, Wayne

ughhh i got lost in the sauce between the OP and the hypothetical. lol

 

[wwhitney]

We were speaking to your hypothetical in post #17, and saying that for the general case, only such a thing as an Emergency Disconnect or Meter Disconnect could get you out of considering the first disconnect to be the Service Disconnecting Means.

230.91 says "The service overcurrent device shall be an integral part of the service disconnecting means or shall be located immediately adjacent thereto." In my hypothetical, I choose the second option. What says I can't, just because there's some other overcurrent device integral to the service disconnecting means? I'm going to call that fuse the "bonus switch protection device" and call my 400A breaker the "service overcurrent device."

I admit this question is academic, as the more sure code compliance path for my hypothetical arrangement is just to use 230.82(3) and slap a "meter disconnect, not service equipment" sticker on the fused disconnect. That makes the 400A breaker both the service disconnect and service overcurrent device. But the point of the hypothetical is to explore 230.91, not to figure out the simplest code compliance path.

A real world example of using the "immediately adjacent thereto" option in 230.91 would be of interest.

Cheers, Wayne

 

[Elect117]

230.91 says "The service overcurrent device shall be an integral part of the service disconnecting means or shall be located immediately adjacent thereto." In my hypothetical, I choose the second option. What says I can't, just because there's some other overcurrent device integral to the service disconnecting means? I'm going to call that fuse the "bonus switch protection device" and call my 400A breaker the "service overcurrent device."

I admit this question is academic, as the more sure code compliance path for my hypothetical arrangement is just to use 230.82(3) and slap a "meter disconnect, not service equipment" sticker on the fused disconnect. That makes the 400A breaker both the service disconnect and service overcurrent device. But the point of the hypothetical is to explore 230.91, not to figure out the simplest code compliance path.

A real world example of using the "immediately adjacent thereto" option in 230.91 would be of interest.

Cheers, Wayne

I personally think you are using the fused disconnect as both. And should meet the requirements for service overcurrent protection AT that location. I would only accept an "immediately adjacent to" if we are talking like a separate switchgear section but the same switchgear. I would not accept it being a separate enclosure. Especially if you already can swap out the 600A fuses for 400As or increase the wire size and it is done.

Every instance of the phrase "immediately adjacent to" requires context and it is not specified.

 

[wwhitney]

I would only accept an "immediately adjacent to" if we are talking like a separate switchgear section but the same switchgear. I would not accept it being a separate enclosure.

Clearly a separate enclosure is allowed, otherwise there'd be no need for that language in 230.91 at all. If it's in the same enclosure, it's arguably an "integral part".

Now I would be OK with interpreting "immediately adjacent to" to mean that the enclosures have to be all but touching (only separated enough for the covers not to interfere). Seems a little strict, I don't see what harm 6" would do, but "immediately adjacent to" is not a defined term.

Cheers, Wayne