[RE-wrenches] Remote battery disconnects

Sat Jan 28 10:12:18 PST 2023

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.
Penrose Colorado 81240

Sent by Jeremy's iPhone. Sorry for typos and shorthand.

On Jan 28, 2023, at 7:28 AM, Christopher Warfel via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:

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

Miller Solar
17395 Oak Road, Atascadero, CA 93422
805-438-5600
www.millersolar.com<http://www.millersolar.com/>
CA Lic. 773985

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at 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.

-Glenn
Sent from my 'smart'phone, so please excuse typos and spelling errors.

------ Original message------
From: William Miller via RE-wrenches
Date: Fri, Jan 27, 2023 2:26 PM
To: RE-wrenches;
Cc: William Miller;
Subject:[RE-wrenches] Remote battery disconnects

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<tel:805-438-5600>
www.millersolar.com<http://www.millersolar.com/>
CA Lic. 773985

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--
                                         Christopher Warfel
                     ENTECH Engineering, Inc.
PO Box 871, Block Island, RI 02807
                                                            401-466-8978
<http://entech-engineering.com>
<http://entech-engineering.com>

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