mortimer
third party inspector
- Location
- New England
- Occupation
- retired
Can you tap a feeder for a line side tap. In other words, can the tap go between the meter main and the, now new, sub panel ?
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PV question
- Thread starter mortimer
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david
Senior Member
- Location
- Pennsylvania
If you are taping a feeder than it is not a line side tap
Inverter output circuits often combine in a solar panel outside of a building than from the panel make a line side tap to the service conductor (S) to the building
Inverter output circuits often combine in a solar panel outside of a building than from the panel make a line side tap to the service conductor (S) to the building
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
If it's a feeder we call that a 'load side tap'.
See the following code section for the rules for doing this:
2017 NEC: 705.12(B)(2)(2).
2014 NEC: 705.12(D)(2)(2).
Note that you typically need additional 'downstream' overcurrent protection for the feeder, unless you have the opportunity to upsize the feeder wire, or downsize the breaker protecting it. So far I have only done these when I can convert the downstream sub to a main breaker panel. For small feeders (100A or less), I usually find it cheaper and easier to insert a subpanel into the feeder instead of doing a tap.
See the following code section for the rules for doing this:
2017 NEC: 705.12(B)(2)(2).
2014 NEC: 705.12(D)(2)(2).
Note that you typically need additional 'downstream' overcurrent protection for the feeder, unless you have the opportunity to upsize the feeder wire, or downsize the breaker protecting it. So far I have only done these when I can convert the downstream sub to a main breaker panel. For small feeders (100A or less), I usually find it cheaper and easier to insert a subpanel into the feeder instead of doing a tap.
david
Senior Member
- Location
- Pennsylvania
Can you tap a feeder for a line side tap. In other words, can the tap go between the meter main and the, now new, sub panel ?
If it's a feeder we call that a 'load side tap'.
What i think the op is asking, the existing utility meter enclosure is being removed. The meter main panel is being installed in place of the existing meter. The meter main exterior panel is now being used for the inverter(s) output circuit (s). The op is intending to do a line side Tap in the new exterior panel
The OP is referring to the existing service panel as a sub feed panel from the new meter main panel
If that is true it would infer the new meter main panel (solar) would be a service disconnect for the utility service
It is unclear if the OP changed the service entrance cable and replaced it with SER cable (sub feed)
If the meter main panel was defined as a "solar" panel and used to tap or as a combining panel if more than one inverter circuit from the PV system
I think it needs clarified exactly what the op is attempting to do
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
I didn't read that much into the OP's question. But I also think it's unlikely to matter. If he wants to tap conductors that meet the NEC definition of a feeder then the rules I mentioned apply. Other rules may apply to his installation, but that wasn't the scope of his question.
david
Senior Member
- Location
- Pennsylvania
Perhaps my assumption is derived based on the OP asking about a line side Tap, all though the OP refers to a feeder tap and a new sub-panel, which leans towards your reading of his post and towards your references given
mortimer
third party inspector
- Location
- New England
- Occupation
- retired
So........I can't find, where it says in 705 anything about feeder taps for PV systems.
Does this mean that it can't be done, or can it be done, following 705.12 (B)(2)(2)
Does this mean that it can't be done, or can it be done, following 705.12 (B)(2)(2)
david
Senior Member
- Location
- Pennsylvania
what year NEC are you looking at for a load side connection point
mortimer
third party inspector
- Location
- New England
- Occupation
- retired
2017what year NEC are you looking at for a load side connection point
david
Senior Member
- Location
- Pennsylvania
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
So........I can't find, where it says in 705 anything about feeder taps for PV systems.
Does this mean that it can't be done, or can it be done, following 705.12 (B)(2)(2)
In the 2014 NEC it's 705.12(D)(2)(1) Feeders. In the 2017 NEC it's in 705.12(B). You can tap a feeder as long as there is OCPD on the load side of the tap or if the conductors between the tap and the loads are rated for the OCPD on the feeder plus 125% of the max inverter current.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
Sorry for the imprecise code reference.
To answer the question 'can it be done', yes it can, like any tap, with some extra rules.
The feeder you tap has to comply with:
2017 NEC: 705.12(B)(2)(1).
2014 NEC: 705.12(D)(2)(1).
The tap conductors to your fused disconnect have to comply with:
2017 NEC: 705.12(B)(2)(2).
2014 NEC: 705.12(D)(2)(2).
This part is really badly worded, but what they mean (I think) is:
-take the breaker for the feeder
-add 125% of the inverter output
-use this sum to calculate your minimum tap conductor size per 240.21(B) (i.e. 10% of that number for 10ft tap, 33% for 25ft tap, etc.)
-(they also must be sized for at least 125% of the inverter output, of course)
I tried to get the grammar fixed on this section last code cycle but the code making panel seems to think it's okay as is.
To answer the question 'can it be done', yes it can, like any tap, with some extra rules.
The feeder you tap has to comply with:
2017 NEC: 705.12(B)(2)(1).
2014 NEC: 705.12(D)(2)(1).
The tap conductors to your fused disconnect have to comply with:
2017 NEC: 705.12(B)(2)(2).
2014 NEC: 705.12(D)(2)(2).
This part is really badly worded, but what they mean (I think) is:
-take the breaker for the feeder
-add 125% of the inverter output
-use this sum to calculate your minimum tap conductor size per 240.21(B) (i.e. 10% of that number for 10ft tap, 33% for 25ft tap, etc.)
-(they also must be sized for at least 125% of the inverter output, of course)
I tried to get the grammar fixed on this section last code cycle but the code making panel seems to think it's okay as is.
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