| Every single house I’ve looked at in my town has a breaker panel with a main service disconnect on the outside of the house already. So in many cases we are well beyond worrying about someone “flicking your switch!”
In fact, in addition to the emergency disconnect requirement for stationary standby batteries [480.7(B)] and ESS [706.15(B)] in one- and two-family dwellings, also added in 2020 was the requirement for an emergency disconnect for services on those same one- and two-family dwellings [230.85]. Brian Mehalic On Jan 28, 2023, at 5:58 PM, James Jarvis via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote:
It would be nice if the decision was up to the owner / occupant of the property. I, for one, do not want any random person to be able to turn off my house or business with the flick of a switch. I feel strongly that there is far too much fear mongering in NEC with relation to renewable energy. Esteemed wrenches:
Well if my house is on fire and the entry of fire responders is delayed for lack of a disconnect, I choose having the disconnect. I can worry about the charge controllers later.
Others may prioritize their charge controller over their homes…
Put a cable-tie lock in the closed position to discourage kids from messing with it. Test it only after dark.
William All
One thing that no one is talking about is what happens to the MPPT charge controllers when the Battery Disconnect trips when the charge controllers are under full load. Many will blow up. Try turning off the battery breaker on a SolaArk when the charge controllers are maxed, and see if you get lucky.
Jeremy: Thanks for posting the code references for those that had never looked them up. Chris: What do you mean by “a disconnect for AC wiring, not specific to which or both panel types”? All: Code references are handy when receiving edicts from building officials, but not required, IMHO, for two reasons: The contractor should already be versed in the codes and, building departments can mandate their own requirements above and beyond the code. It may seem redundant to require an AC disconnect for premise wiring as well as a DC battery disconnect. In most cases if you disconnect the inverter from the batteries the AC power goes off. However if the generator is running at the time, some battery inverters can operate when disconnected from batteries. So to completely de-energize all components of an off-grid home you need to disconnect the generator and the battery leads. In this case the home is required to have fire sprinklers. There is pressure pump to provide flow to these fire sprinklers-- said pump being powered by the inverter/battery system. I am going to apply for a waiver to remove the DC disconnect requirement on the grounds that the pressure pump is essential fire suppression equipment. Instead I will propose to supply an AC disconnect (meeting all requirements for accessibility and marking) that will disconnect all premise wiring except the pressure pump. By the way, I will of course be trying to apply the logic that the voltage specification is for nominal battery voltage and this project having a nominal 48 volt bank does not require the battery disconnect. I will let the group know what response I receive. Regardless of how this works in this jurisdiction, I think these are both valid arguments worth trying in any jurisdiction requiring the battery disconnect. Some officials are amenable to dialog and negotiation and some are less so. William Miller 2020 Code Language: 480.7 DC Disconnect Methods. (A) Disconnecting Means. A disconnecting means shall be provided for all ungrounded conductors derived from a stationary battery system with a voltage over 60 volts dc. A disconnecting means shall be readily accessible and located within sight of the battery system. N (B) Emergency Disconnect. For one-family and two-family dwellings, a disconnecting means or its remote control for a stationary battery system shall be located at a readily accessible location outside the building for emergency use. The disconnect shall be labeled “EMERGENCY DISCONNECT”. N (C) Disconnection of Series Battery Circuits. Battery circuits exceeding 240 volts dc nominal between conductors or to ground and subject to field servicing shall have provisions to disconnect the series-connected strings into segments not exceeding 240 volts dc nominal for maintenance by qualified persons. Non-load-break bolted or plug-in disconnects shall be permitted. Jeremy Rodriguez Solar Installation / Design All Solar, Inc. 1453 M St. Sent by Jeremy's iPhone. Sorry for typos and shorthand. Seems confusing that the AHJ is requiring a disconnect for AC wiring, not specific to which or both panel types, and then a dc disconnect with no code reference. Was trying to convey a reasonable, safe approach. A lot of bad information from fire department solar consultants making a lot of money fear mongering, which has led to this type of situation. Chris On 1/27/2023 3:35 PM, William Miller via RE-wrenches wrote: Glenn: As I wrote, a DC disconnect is required. Here is an excerpt from the Q&A with the building official: 4. Will you be requiring an external disconnect to disconnect the AC output of the inverter system from premise wiring? Yes, as required per 230.85 5. Will you be requiring an external disconnect to disconnect batteries from the inverters? Yes If the DC disconnect was not required I would not be wasting everyone’s time with my post. I try to be careful about that, researching on my own before posting and trying to make my questions very clear. I also try not to embarrass myself with dumb questions, but that does happen occasionally… William From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Glenn Burt via RE-wrenches
Sent: Friday, January 27, 2023 11:46 AM
To: William Miller via RE-wrenches
Cc: Glenn Burt
Subject: Re: [RE-wrenches] Remote battery disconnects Does the AHJ really want the batteries disconnected from conductors, or does he really just want the inverters to stop operating and producing AC within the house? Obviously there is a big difference here and it may be changing as the code evolves. Sent from my 'smart'phone, so please excuse typos and spelling errors. Friends: We have a large-ish residential off-grid system install coming up. The AHJ has said they will require a remote battery disconnect. I suspect there will be fire sprinkler controls and a pressure pump that would become inoperable if this system were engaged. In this case we will apply for a waiver. The last time this was discussed here as far as I can find was October of 2020. At that time no one suggested any specific battery disconnect equipment. To further clarify my needs: There will be 4 or 5 Radian 8048 inverters (5 or 6 4/0 battery circuits, ~350A each) and two 175 amp PV recombiner outputs. That is 6 poles of high amperage DC disconnects. The battery array will be either a UnigyII VRLA or a lithium of a brand yet to be determined. In the case of lithium we will look for a system that can remotely enable a BMS shutdown. In the case of a VRLA lead-acid, we will not have that luxury. I have done some considerable research and have not found viable, high amperage, remotely activated shutdown equipment. I am wondering what hardware others may be using to achieve remote battery disconnecting in these types of cases.. William Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com CA Lic. 773985
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