Hendrix
Senior Member
- Location
- New England
On a PV system a line side tap is allowed under an exception. Duz this tap need to be before the first disco. or, can it be between two discos?
Line side tap.
- Thread starter Hendrix
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Carultch
Senior Member
- Location
- Massachusetts
If it is between two disconnects, it is a feeder tap.
If it is on the line side of the main service disconnect, it is a line side tap.
Some may argue that this doesn't formally meet the definition of a tap. In my opinion, a tap is the best model we have for it. It is a section of conductor that is only protected in excess of its ampacity, and follows specific rules to minimize overload damage as much as possible.
In any case, follow the tap rules of 240.21(B), size the EGC per the feeder or service, and you have to terminate in a dedicated OCPD and integral/adjacent disconnecting means for the PV system.
Hendrix
Senior Member
- Location
- New England
So................if there is no room, due to a meter socket, disconnect combo. One would have to rearrange the service?
Depends on the meter/main combo. Some have provisions (such as having two mains or an optional accessory second main), some can be tapped through listed accessory modifications (rare), some (most) cannot. For the latter, rearrangement could be "simple" as replacement with one of the former.
There is no formal definition of a line side (i.e. service) tap, but I believe everyone accepts that it is any service conductor which has ampacity less than the service rating.
Only applies to a feeder tap.
Carultch
Senior Member
- Location
- Massachusetts
So in the event of a supply-side service tap, what is the sizing procedure for the tap circuit wiring, EGC's, GEC's, and where (if anywhere) neutral/ground need to be bonded?
If it is different from the sizing of the circuit in general.
Sizing ungrounded conductors is no different than circuits in general, but reaching that conclusion is most certainly not straightforward. While debate abounds whether the PV System disconnect is a Service Disconnecting Means, I believe everyone agrees that the line side conductors are considered service-entrance conductors. The tricky part is that service-entrance conductors size and rating are required to be based on Article 220 calculated load. As you know, PV Systems present essentially no load to the service. However, considering the PV system's load is service connected loads or the service itself, we conclude these ungrounded conductors must be sized and rated not less than the PV system side of the disconnect.
There are no EGC's on the service side of any disconnecting means. Where the service is a grounded system, all exposed non-current-carrying metal parts are bonded to the grounded conductor. Where there is no service grounded conductor run to the PV system disconnect (only permitted where the PV system doesn't require a grounded circuit conductor and the disconnect is not considered a service disconnecting means) or the service system is ungrounded, bonding is per Article 250 Part V.
Grounded/grounding bonding jumpers seem to be a little tricky, too, especially in the wake of the service disconnecting means (SDM) or not debate. But IMO it does not matter regarding the grounded/grounding bonding jumper because where not considered an SDM and a grounded service conductor is required, it will simply be desired to avoid having to run a equipment bonding jumper. In this case, the grounded service conductor cannot be smaller than the minimum grounded/grounding jumper, which in turn cannot be smaller than a minimum size AC EGC/GEC conductor on the PV side.
A GEC is only required if disconnect is considered an SDM, and the appropriate section(s) apply.
I think I covered all the possibilities. I'm sure someone will let me know if I haven't.
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