Disconnect Switch Ahead of CT Cabinet (NYC ConEdison)

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Tainted

Tainted

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I've been told that ConEdison does not allow disconnect switches ahead of the CT cabinet but I've seen it done, is there an exception to it? For example I've seen a NYC apartment building that had a service end box which was feeding only a switchboard. This switchboard had a 1200A main service switch feeding metered loads and the switchboard didn't have any CT cabinet in it. It also fed a house panel via fused switch and feeder, and the house panel had a CT cabinet ahead of it. How was this allowed? did they get permission from POCO?
 
Usually called “cold sequence metering” Only seen it done on 400 amp and under 480 volt services, but could be on other services. Multi meter setups like that, are as you said, have a single main feeding a meter groups are common too. A lot of malls are like that.
 
hillbilly1 said:
Usually called “cold sequence metering” Only seen it done on 400 amp and under 480 volt services, but could be on other services.
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So does that mean you can do cold sequence metering depending on amperage? I really want to know when I can and cannot do it, effects my design lol
 
Tainted said:
I've been told that ConEdison does not allow disconnect switches ahead of the CT cabinet but I've seen it done, is there an exception to it? For example I've seen a NYC apartment building that had a service end box which was feeding only a switchboard. This switchboard had a 1200A main service switch feeding metered loads and the switchboard didn't have any CT cabinet in it. It also fed a house panel via fused switch and feeder, and the house panel had a CT cabinet ahead of it. How was this allowed? did they get permission from POCO?
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I am upstate, and unfamiliar with ConEd requirements, but we have people on here that do. I'm pretty sure someone will chime in.

Regarding the setup you mention: are you sure there were not CT's in the switchboard? It doesn't take much space and won't look like a CT cabinet. Also, it could be metered with CT's on the transformer spades (usually pad mount though. I assume unlikely on submersible vault transformers).
 
Unlike up North, down here in the South, like Electrofelon said, the CT’s are usually on the stabs of the pad mount transformer output. Much smaller CT’s can be used, and the poco gets to bill for any power lost due to voltage drop on the service lateral.
 
Tainted said:
So does that mean you can do cold sequence metering depending on amperage? I really want to know when I can and cannot do it, effects my design lol
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Here, the poco requires it for small 480 services. They use bolt in meters instead of CT’s, this allows the meter installer to remove and install the meter without having to kill the transformer.
 
Tainted said:
So does that mean you can do cold sequence metering depending on amperage? I really want to know when I can and cannot do it, effects my design lol
Click to expand...
Every utility has a set of rules for each voltage and service size. They usually have a PDF on installation requirements on web site. Point being, always ask or look it up.
 
Tainted said:
I've been told that ConEdison does not allow disconnect switches ahead of the CT cabinet but I've seen it done, is there an exception to it? For example I've seen a NYC apartment building that had a service end box which was feeding only a switchboard. This switchboard had a 1200A main service switch feeding metered loads and the switchboard didn't have any CT cabinet in it. It also fed a house panel via fused switch and feeder, and the house panel had a CT cabinet ahead of it. How was this allowed? did they get permission from POCO?
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How old was the install with the 1200A switch? The only thing I can think of was that the switchboard was put in place in order to achieve some level of series rated protection where there is a high available fault current at the service entrance that would be seen by the main service switch before getting to the meter bank breakers with a lower interrupting rating.
 
electrofelon said:
I am upstate, and unfamiliar with ConEd requirements, but we have people on here that do. I'm pretty sure someone will chime in.

Regarding the setup you mention: are you sure there were not CT's in the switchboard? It doesn't take much space and won't look like a CT cabinet. Also, it could be metered with CT's on the transformer spades (usually pad mount though. I assume unlikely on submersible vault transformers).
Click to expand...
I’m sure, I even looked at the plans, they were fairly new plans too
 
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