new to CT cabinets

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Electron_Sam78

Electron_Sam78

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Palm Bay, FL
I've never installed a service with a CT cabinet but I'm about to do it soon. In my perusing of the code book I can't figure out what table I use to bond the small meter enclosure which is mounted next to the CT cabinet. Would it be considered a supply side bonding jumper and be sized accordingly since it originates in the CT cabinet and travels to the meter enclosure (PVC is used between the two)? That would make it 2/0 copper in my 600 amp application with paralleled 350s
 
Last CT can I did had a #6 bare copper going to the meter enclosure. That is what the inspector asked for. I guess because the service conductors do not go to the meter, you do not need the NEC-sized bond.
 
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It would make sense to treat it as if it were a supplyside bonding jumper. In a separately derived system with a system bonding jumper at the disconnect and not the transformer, the supplyside bonding jumper is sized according to NEC Table 250.66. A fault on the supply side of the disconnect would not trip the OCPD so the bonding jumpers would have to be bigger than specified by NEC Table 250.122.
 
jeremysterling said:
Last CT can I did had a #6 bare copper going to the meter enclosure. That is what the inspector asked for. I guess because the service conductors do not go to the meter, you do not need the NEC-sized bond.
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Yeah, to me it would make sense to size it according to the fault that could happen inside the meter can with those #12s. Since the CT cabinet is bonded with a 2/0 copper to the supply neutral a fault would be cleared using that jumper.
 
There are no service conductors in the socket for a CT meter or the raceway. There are no special bonding requirements for either. The EMT or RMC run from the CT cabinet to the meter socket can serve as the grounding means of the meter socket.

Of course the power company may have there own rules.
 
CT cans vary by poco - consult your poco's greenbook. some pocos here do not allow grounding conductors in their CT, and if inspector or job layout requires a bonding conductor it has to be run outside the can.
 
We usually use myers hubs on both sides with a rigid nipple between to take care of the bonding requirements.

Something else that isn't in the NEC, is that our POCO's require us to put the meter on the latched side of the CT can, not the hinged side where the door will swing back into it. And don't forget to rope the wires if the CT can requires it, ours usually show a diagram on the inside on how to do it.
 
... And don't forget to rope the wires if the CT can requires it, ours usually show a diagram on the inside on how to do it.
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There's no reason for me to guess, can you explain this statement more, Thank You!
 
Well first the meter base is the power companys box so the NEC doesnt rule on this install .

If you ask your power company for a book on there rules its only a number 4# bare today we install a ground in a ct meter base with ground rod under meter base to a ground lug inside meter base encloser and we put it in a conduit so the copper bums will not steal it .

If you put a 2/0 copper in it they will make you take it out and its not going to fit thats any state in our fine country .

CT s go in ct cabinet on wooden backboard ct wires go thur nipple to meter base and the ground goes to base via ct cabinet .

But its not for a major fault its just a bonding thing so bigg wire is not used !

There is no NEC table used its just a ground point.
 
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