6 handle rule and PV SSC

[Humpiestrhyme]

Hello,

I have a question I’m hoping to get answered here. Looking for a theoretical scenario. Any thoughts are appreciated!

I have a MSP with 6 breakers. Can I ssc the PV and get away with the 6 handle rule? Does the (fused) PV disconnect count as #7 = violation?

2017 NEC
Part IV. Service-Entrance Conductors
230.40 Number of Service-Entrance Conductor Sets. Each service drop, set of overhead service conductors, set of under‐ ground service conductors, or service lateral shall supply only one set of service-entrance conductors.

Exception No. 5: One set of service-entrance conductors connected to the supply side of the normal service disconnecting means shall be permitted to supply each or several systems covered by 230.82(5) or 230.82(6).

230.82 Equipment Connected to the Supply Side of Service Disconnect. Only the following equipment shall be permitted to be connected to the supply side of the service disconnecting means:

(6)Solar photovoltaic systems, fuel cell systems, wind electrictic systems, energy storage systems, or interconnected electric power production sources.

230.71 Maximum Number of Disconnects.
(A) General. The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception No. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or in switchgear. There shall be not more than six sets of disconnects per service grouped in any one location.
For the purpose of this section, disconnecting means instal‐ led as part of listed equipment and used solely for the following shall not be considered a service disconnecting means:
(1) Power monitoring equipment
(2) Surge-protective device(s)
(3) Control circuit of the ground-fault protection system (4) Power-operable service disconnecting means



Please help, thanks!

 

[electrofelon]

Hello,

I have a question I’m hoping to get answered here. Looking for a theoretical scenario. Any thoughts are appreciated!

I have a MSP with 6 breakers. Can I ssc the PV and get away with the 6 handle rule? Does the (fused) PV disconnect count as #7 = violation?

2017 NEC
Part IV. Service-Entrance Conductors
230.40 Number of Service-Entrance Conductor Sets. Each service drop, set of overhead service conductors, set of under‐ ground service conductors, or service lateral shall supply only one set of service-entrance conductors.

Exception No. 5: One set of service-entrance conductors connected to the supply side of the normal service disconnecting means shall be permitted to supply each or several systems covered by 230.82(5) or 230.82(6).

230.82 Equipment Connected to the Supply Side of Service Disconnect. Only the following equipment shall be permitted to be connected to the supply side of the service disconnecting means:

(6)Solar photovoltaic systems, fuel cell systems, wind electrictic systems, energy storage systems, or interconnected electric power production sources.

230.71 Maximum Number of Disconnects.
(A) General. The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception No. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or in switchgear. There shall be not more than six sets of disconnects per service grouped in any one location.
For the purpose of this section, disconnecting means instal‐ led as part of listed equipment and used solely for the following shall not be considered a service disconnecting means:
(1) Power monitoring equipment
(2) Surge-protective device(s)
(3) Control circuit of the ground-fault protection system (4) Power-operable service disconnecting means



Please help, thanks!

The PV can be a 7th switch. See the part i highlighted and especially the word "each".

 

[ggunn]

The PV can be a 7th switch. See the part i highlighted and especially the word "each".

It depends on code interpretation by the AHJ, but Mike Holt has video and training materials that make a good case for a PV line side connection not counting as a seventh handle when there are six existing service disconnects. I took some screenshots from Mike's video to my local AHJ when this issue came up for me here, and I got a ruling in my favor.

YMMV, of course.

 

[electrofelon]

It depends on code interpretation by the AHJ, but Mike Holt has video and training materials that make a good case for a PV line side connection not counting as a seventh handle when there are six existing service disconnects. I took some screenshots from Mike's video to my local AHJ when this issue came up for me here, and I got a ruling in my favor.

YMMV, of course.

I'll have to look it over in more detail , as I don't immediately see how there could be any debate about it.

 

[ggunn]

I'll have to look it over in more detail , as I don't immediately see how there could be any debate about it.

From memory, for what that's worth...

I think the point was that the code dictates a maximum of 6 handles controlling power flow from a single source but PV is a different source. I have a couple of systems out there inspected and running where there are 6 breakers in an MLO MDP with PV tapped onto the service conductors.

 

[jaggedben]

This has been a controversial point, but it may cease to be. The First Draft of the 2020 NEC explicitly exempts PV disconnects from being counted towards 230.71. It's in the new 705.11 for supply side connections.

 

[jaggedben]

Another thing to watch out for is that if you have an MLO panelboard use as service equipment, the label likely includes anf instruction not to use more than six circuit breakers. That kinda screws you regardless of what the code says.

 

[ggunn]

Another thing to watch out for is that if you have an MLO panelboard use as service equipment, the label likely includes anf instruction not to use more than six circuit breakers. That kinda screws you regardless of what the code says.

Something I see fairly often and that I saw again a few minutes ago is a residential MLO panel just behind the meter with no OCPD between it and the meter. The one I am looking at at the moment has about 40 circuit breakers in it. Isn't this a code violation?

 

[jaggedben]

Something I see fairly often and that I saw again a few minutes ago is a residential MLO panel just behind the meter with no OCPD between it and the meter. The one I am looking at at the moment has about 40 circuit breakers in it. Isn't this a code violation?

Yes, it's a code violation. :lol::lol::lol:

I've seen that once or twice when unpermitted work was done. I'm surprised you see it 'fairly often'.

 

[Carultch]

The PV can be a 7th switch. See the part i highlighted and especially the word "each".

If the PV is the 7th switch, are both of the following solutions acceptable? Or is only one of these acceptable?
1. Built in an MLO panelboard (or switchboard), with 6 other branch breakers as service disconnects for building loads
2. Installed as a separate fused disconnect, with the line side conductors tapped to the service conductors

The other questions:
If it is built in an MLO panelboard of service disconnect breakers, how does the busbar ampacity requirement get determined? Like an equivalent of the 120% rule.
If it is built as a separate fused disconnect, should neutral and ground be bonded, even if they are bonded in all other service disconnects on the same building?

 

[electrofelon]

If the PV is the 7th switch, are both of the following solutions acceptable? Or is only one of these acceptable?
1. Built in an MLO panelboard (or switchboard), with 6 other branch breakers as service disconnects for building loads
2. Installed as a separate fused disconnect, with the line side conductors tapped to the service conductors

The other questions:
If it is built in an MLO panelboard of service disconnect breakers, how does the busbar ampacity requirement get determined? Like an equivalent of the 120% rule.
If it is built as a separate fused disconnect, should neutral and ground be bonded, even if they are bonded in all other service disconnects on the same building?

Disclaimer: I have not refreshed myself with all the nitty gritty of this lately and am not up on what 2017 or 2020 say and dont care enough to spend 45 minutes reading and thinking on it, but from memory and FWIW, I think the MLO panelboard case is the sticky one because you are not really making and connecting another set of service entrance conductors so it doesnt really fit into what 230.40 exception #5 says. Also adding a 7th in a MLO is sticky because of the "not more than 6 disconnects grouped in one location" clause in 230.71. Your #2 seems pretty clear cut, and I would say it can be grouped with the "normal" disconnects if there are 5 or less, but doesnt have to.

 

[jaggedben]

If the PV is the 7th switch, are both of the following solutions acceptable? Or is only one of these acceptable?
1. Built in an MLO panelboard (or switchboard), with 6 other branch breakers as service disconnects for building loads
2. Installed as a separate fused disconnect, with the line side conductors tapped to the service conductors

2 would be okay (if you buy the overall argument). 1 has both the problem electrofelon mentioned (same set of service entrance conductors) as well as the more insurmountable likelihood of not following the listed equipment's instructions (see posts above.)

The other questions:
If it is built in an MLO panelboard of service disconnect breakers, how does the busbar ampacity requirement get determined? Like an equivalent of the 120% rule.

Busbar just has to meet the calculated load on the service. See 230.40 Exception 2.

If it is built as a separate fused disconnect, should neutral and ground be bonded, even if they are bonded in all other service disconnects on the same building?

This has been a point of a lot of debate. It seems in 2020 the CMP has finally decided to weigh in. Keep in mind this is First Draft, so may still change, possibly greatly. New section 705.11. Check out (D) for the answer to your question. See (F) for main subject of this thread. Red text is me adding footnotes.

705.11 Supply-Side Source Connections.

An electric power production source, where connected on the supply side of the service disconnecting means as permitted in 230.82(6), shall comply with 705.11(A) through (F).

(A) Output Rating.
The sum of the power source continuous current output ratings on a service, other than those controlled in accordance with 705.13, shall not exceed the ampacity of the service conductors.
Informational Note: See Article 100 definition for Service Conductors. [Not changed]

(B) Conductors.
The power source output circuit conductors from the service conductors point of connection to the first overcurrent protection device shall be sized in accordance with 705.28 and in no case sized smaller than #6 AWG copper or #4 AWG aluminum. These conductors shall be installed in accordance with 230.30 or 230.43. [705.28 is basically the current 705.60 and 705.95 reorganized and combined.]

(C) Overcurrent Protection.

The power source output circuit conductors shall be protected from overcurrent in accordance with 705.28 and 705.30. [705.30 is overcurrent protection, renumbered from 705.65] If fuses are not integral with the disconnecting means the disconnecting means shall be located on the service side of the fuses. Where the power source output circuit conductors make their connection to the service outside of a building, they shall be protected by overcurrent devices in a readily accessible location outside the building or at the first readily accessible location where the power source conductors enter the building. Where the power source output circuit conductors make their connection to the service inside a building, they shall be protected with one of the following methods:

1. Within 5 m (16.5 ft). With an overcurrent device within 5 m (16.5 ft) of conductor length from the point of connection to the service
2. Within 20 m (71 ft). With cable limiters at the connection to the service and an overcurrent device located within 20 m (71 ft) of conductor length from the point of connection to the service

(D) Bonding and Grounding.
All metal enclosures, metallic wiring methods, and metal parts associated with the power source output conductors in 705.11(B) shall be bonded in accordance with 250.92(B). This metallic equipment shall be connected to the grounding electrode system for the service at the power source disconnecting means with only one of the methods in 705.11(D)(1) or (D)(2). Where the power sources use a grounded conductor, 705.11(D)(1) shall apply.

(1) Grounded Conductor Brought to Power Source Disconnecting Means.
Where a grounded service conductor is brought to the power source disconnecting means, the grounded conductor shall be connected to the disconnecting means grounded conductor terminal or bus. A bonding conductor shall connect the grounded service conductor to the metallic equipment enclosing the power source output circuit conductors. This bonding conductor shall be sized in accordance with 250.102 based on the size of the power source output circuit conductors.

(2) Grounded Conductor Not Brought to Power Source Disconnecting Means.
Where a grounded service conductor is not brought to the power source disconnecting means, the metallic equipment enclosing the power source output circuit conductors shall be bonded to the grounding electrode system using a separate bonding conductor sized in accordance with 250.102 based on the size of the power source output circuit conductors.

(E) Connections.
The connection of power source output circuit conductors to the service conductors shall be made using listed connectors as described in 110.14 and comply with all enclosure fill requirements Any modifications to existing equipment shall be made in accordance with the manufacturer’s instructions or the modification must be field labeled.
Informational Note: Electric utilities enforce their requirements for connections to equipment under their control. See 90.2.

(F) Disconnecting Means.
The power source disconnecting means shall meet the requirements of 705.20. The power source disconnecting means shall not be considered as one of the service disconnecting means as required by 230.70. The requirements of 230.71 or 230.72 shall not apply to the power source disconnecting means. The conductors between the point of connection and the disconnect shall be connected to the line side of the disconnect.

(G) Ground-Fault Protection.
For connections rated 1000 amperes or more to solidly grounded wye services exceeding 150 volts to ground but not exceeding 1000 volts, phase-to-phase, ground-fault protection meeting the requirements of 230.95 shall be provided.

Final note: The Article 100 definition of a service is going to change if the First Draft holds, so Mike Holt's argument would go away if that happened.

 

[shortcircuit2]

Its good to see CMP-4 is hearing the industries cries for change on the service disconnect associated with a line side interconnection.

2020's 705.11 (drafted by CMP-4) is result of these cries for change. Alot of language transposed from the front of the book to the rear of the book. All unnecessary IMO. Just call the interconnect disconnect what it is (service disconnect), and follow the rules in the front of the book.

The 7th disconnect dilemma is the issue on that front. The PV rule writers do not want to deal with all those existing 6-switch services without a main when adding an electric power production source...as is the case in this thread here. But, 230.2(A)(5) could be applied in such cases and an additional service would be permitted for the Parallel Power Production System, IMO.

 

[ggunn]

If the PV is the 7th switch, are both of the following solutions acceptable? Or is only one of these acceptable?
1. Built in an MLO panelboard (or switchboard), with 6 other branch breakers as service disconnects for building loads
2. Installed as a separate fused disconnect, with the line side conductors tapped to the service conductors

When I successfully negotiated adding PV to a MLO MDP with six breakers feeding loads/subpanels, the AHJ directed me to go with option 2.