Battery systems back feeding a house.

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acrwc10

acrwc10

Master Code Professional
Location
CA
Occupation
Building inspector
we are seeing a lot of "energy storage systems" (battery backups) being installed. These systems power the house in a power failure and are frequently inside of the house where the fire department may not know they are back feeding the house. My question is what code section would best apply to require a disconnect for the battery output be located at the main service disconnect?
 
Sorry I should have added we are still using the 2014 NEC in California.
 
If on the 2014 then I would look at 702 optional standby power systems. only labeling seems to be required.

I wonder what 706 has in store for us next year.
 
acrwc10 said:
we are seeing a lot of "energy storage systems" (battery backups) being installed. These systems power the house in a power failure and are frequently inside of the house where the fire department may not know they are back feeding the house. My question is what code section would best apply to require a disconnect for the battery output be located at the main service disconnect?
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There is no requirement for a disconnect for the battery output to be located near the main service disconnect. However, a directory showing the location of the battery inverter disconnect is required at the main service disconnect, see 705.10.

Cheers, Wayne
 
wwhitney said:
There is no requirement for a disconnect for the battery output to be located near the main service disconnect. However, a directory showing the location of the battery inverter disconnect is required at the main service disconnect, see 705.10.

Cheers, Wayne
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I don't believe article 705 applies here as this is not a power production source in parallel . it is a back-up source only operating when the primary source fails.. This would fall under 702.
If this is similar to a grid tie system then I would agree 705 would apply.


IMHO
 
These are likely paired with a PV system so 705 does apply. Specifically see 705.40, which includes a reference to a stand alone system.

Don't go to 702, it wasn't intended to cover these systems. Also, CA adopted 706 in the intervening code cycle.

Short answer - the code typically treats disconnects in one of two ways...1) it says where the disconnect needs to be, 2) it requires signage indicating where it is. For ESS it's #2 for now.

This is the same as any old backup generator and the fire department just needs to be trained to look for the signs.

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706.15(A) addresses this issue in the 2020 code.
For one-family and two-family dwellings, a disconnecting means or its remote control shall be located at a readily accessible location outside the building.
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I don't think there is any requirement for that in the previous codes.
 
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c_picard said:
These are likely paired with a PV system so 705 does apply. Specifically see 705.40, which includes a reference to a stand alone system.

Don't go to 702, it wasn't intended to cover these systems. Also, CA adopted 706 in the intervening code cycle.

Short answer - the code typically treats disconnects in one of two ways...1) it says where the disconnect needs to be, 2) it requires signage indicating where it is. For ESS it's #2 for now.

This is the same as any old backup generator and the fire department just needs to be trained to look for the signs.

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I don't think the OP is combining with a solar. Maybe so but not clear.
 
Sierrasparky said:
I don't think the OP is combining with a solar. Maybe so but not clear.
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That's the overwhelming majority of ESS installations in the U.S. right now. Either way it's an interactive system operating in stand alone mode, not an optional stand by system. This is where 710 in the 2017 is relevant.



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Sierrasparky said:
I don't think the OP is combining with a solar. Maybe so but not clear.
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some of the systems have solar PV and some are just the battery system. the way they are being connected is similar to a back up generator, when the power is turned off the relay switches the circuits to battery power.
 
So, either way the answer is the same for the disconnect questions.

If it's an actual transfer switch then maybe 702 could be applied by an AHJ, but 710 (2017 but based on 2014 language found elsewhere) makes more sense generally for this technology.

It comes down to sizing the system. A battery system sized to 702 rules is likely way bigger and more expensive than it needs to be.



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c_picard said:
So, either way the answer is the same for the disconnect questions.

If it's an actual transfer switch then maybe 702 could be applied by an AHJ, but 710 (2017 but based on 2014 language found elsewhere) makes more sense generally for this technology.

It comes down to sizing the system. A battery system sized to 702 rules is likely way bigger and more expensive than it needs to be.



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Kiss your garage good-bye.
 
c_picard said:
Sorry, not following. Can you explain?

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It will be full of batteries.

Great Sunday cartoon, I forget the strip. Two kids taking about careers. One says he wants to be an architect, and has all sorts of neat ideas.
"Like a room attached to the house to park your car in."
"You mean like a garage?"
"Yes, only for cars."
 
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