Do exterior main disconnect switches need OC protection?

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jselesk2

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Hi,

Consider the situation where the service conductors enter a point in a residence that is not adjacent to the main circuit breaker panel. I understand that a main disconnecting means will be required along the service conductors at a point before they enter the home. My question is, will this disconnecting means need to also incorporate OC protection if it has a manual disconnect lever? I am also assuming that the circuit breaker panel inside the home already has OC protection. Thanks in advance.
 
jselesk2 said:
Hi,

Consider the situation where the service conductors enter a point in a residence that is not adjacent to the main circuit breaker panel. I understand that a main disconnecting means will be required along the service conductors at a point before they enter the home. My question is, will this disconnecting means need to also incorporate OC protection if it has a manual disconnect lever? I am also assuming that the circuit breaker panel inside the home already has OC protection. Thanks in advance.
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The main service disconnecting means requires overcurrent protection either integral or immediately adjacent to it.
 
david luchini said:
The main service disconnecting means requires overcurrent protection either integral or immediately adjacent to it.
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That said, I've seen where the UTILITY owns the disconnect because it is AHEAD of the meter, and they use an non-fused disconnect. I believe this has been discussed in here before. Utilities don't have to follow the same rules as the rest of us when THEY own the equipment.
 
jselesk2 said:
Hi,

Consider the situation where the service conductors enter a point in a residence that is not adjacent to the main circuit breaker panel. I understand that a main disconnecting means will be required along the service conductors at a point before they enter the home. My question is, will this disconnecting means need to also incorporate OC protection if it has a manual disconnect lever? I am also assuming that the circuit breaker panel inside the home already has OC protection. Thanks in advance.
Click to expand...
Outside of local rules that state otherwise, if the conductors pass beyond what your AHJ allows as "nearest the point of entry" then you must have overcurrent protection on those conductors. If a fault occurs ahead of your service overcurrent protection, there is increased risk of overheating and fire as only thing that may cut out is POCO's primary overcurrent device, but you can't rely on that, for one thing it may trip at a much higher level than the ampacity of the service conductors, especially if you are on a larger transformer that serves mutiple customers.
 
Jraef said:
That said, I've seen where the UTILITY owns the disconnect because it is AHEAD of the meter, and they use an non-fused disconnect. I believe this has been discussed in here before. Utilities don't have to follow the same rules as the rest of us when THEY own the equipment.
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Funny my old boss called me with this exact situation this morning. He is in Arkansas. I am in Florida. down here, Duke requires a switch before the meter on all feed through 480 volt services. We then install our service disconnecting means per the code.

I don't see how you can do you scenario with out still have a service disconnect after the meter. The code requires the service disconnect to have overcurrent protection. 230.91 And not separate as one other poster stated. So, unless the switch has overcurrent protection it can't act as the service disconnect. It can if it has OC protection 230.94 ex#1.
 
Strathead said:
Funny my old boss called me with this exact situation this morning. He is in Arkansas. I am in Florida. down here, Duke requires a switch before the meter on all feed through 480 volt services. We then install our service disconnecting means per the code.

I don't see how you can do you scenario with out still have a service disconnect after the meter. The code requires the service disconnect to have overcurrent protection. 230.91 And not separate as one other poster stated. So, unless the switch has overcurrent protection it can't act as the service disconnect. It can if it has OC protection 230.94 ex#1.
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The nec allows us to call this a "meter disconnect switch" and not a service disconnect.
 
electrofelon said:
The nec allows us to call this a "meter disconnect switch" and not a service disconnect.
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Agreed. The code even allows the service disconnect to be in front of the meter. But then the Utility company has to supply a special meter. One that the neutral is isolated from the enclosure. In Gainesville Florida, the astute Electrical Inspectors have educated the Utility on this.
 
Strathead said:
Agreed. The code even allows the service disconnect to be in front of the meter. But then the Utility company has to supply a special meter. One that the neutral is isolated from the enclosure. In Gainesville Florida, the astute Electrical Inspectors have educated the Utility on this.
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There is an exception allowing metering equipment to be neutral bonded after the service disconnect. I dont remember exactly what it says without looking.

So if I have a "meter disconnect switch" that is a fused disco, can I still elect to call that a meter disconnect switch and not a service disco?
 
electrofelon said:
There is an exception allowing metering equipment to be neutral bonded after the service disconnect. I dont remember exactly what it says without looking.

So if I have a "meter disconnect switch" that is a fused disco, can I still elect to call that a meter disconnect switch and not a service disco?
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I would assume so, but why would you?
 
electrofelon said:
Im looking at 230.91 2014 and it includes the "immediately adjacent thereto" language. Did this change in 2017?
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there is a change stating that if the OC means is fuses, they must be after the disconnect. There is nothing with the words adjacent to. I don't have my 2014 code book in front of me. Just the 2017
 
Strathead said:
there is a change stating that if the OC means is fuses, they must be after the disconnect. There is nothing with the words adjacent to. I don't have my 2014 code book in front of me. Just the 2017
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Your 230.91 must be different from mine. 230.91 says the overcurrent shall be either integral to disconnecting means, or located immediately adjacent to it.
 
david luchini said:
Your 230.91 must be different from mine. 230.91 says the overcurrent shall be either integral to disconnecting means, or located immediately adjacent to it.
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I stand corrected. I looked at it three times and didn't see it until the fourth. How does that happen?
 
Strathead said:
there is a change stating that if the OC means is fuses, they must be after the disconnect. There is nothing with the words adjacent to. I don't have my 2014 code book in front of me. Just the 2017
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Well, yes. If the fuses were before the disco they would be hot all the time. I run into this occasionally with line side connected PV systems. Electricians without experience with PV sometimes insist that the PV should be on the line side of a fused disco. When I ask them how they would change the fuses they usually realize that it has to be the other way round.
 
ggunn said:
Well, yes. If the fuses were before the disco they would be hot all the time. I run into this occasionally with line side connected PV systems. Electricians without experience with PV sometimes insist that the PV should be on the line side of a fused disco. When I ask them how they would change the fuses they usually realize that it has to be the other way round.
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You got me thinking about that, putting the OCPD ahead of the service disconnect. The aforementioned 230.91 doesnt say the OCPD has to be after the the disco. There is 240.4, which requires a disconnecting means on the line side of fuses for some voltages and situations, but then exempts it on the supply side of the disconnecting means as permitted by 230.82. 230.82(1) says "cable limiters or other current limiting devices" not exactly sure if the "other current limiting device" can be the service OCPD? Of course this is pretty much just an academic discussion, as using some sort of fuse block instead of a fused safety switch would be very rare indeed in the <600 world.
 
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