NEC 690.12 (A-D) Rapid Shut Down of PV Systems on Buildings.

[J_Mack58]

https://www.mayfield.energy/blog/nec-2020-rapid-shutdown-requirements

I get it, we don't want to hurt our Firefighters trying to put out a fire on our house that have solar panels but I looked at some commercial devices and their price
and I said "here we go again". And to make matters worst they want you to hang a device on every solar panel to increase their sells. My situation is I have a "String" Inverter and all my PV's are in series. Code say break the DC Power within 12" (300mm) of the PV array. So my DC power comes through the roof, immediately I have a small electrical enclosure with a relay that has DC rated contacts (very important to have DC rated contacts) the coil is 120VAC. The coil is energized by a 15 amp breaker in my breaker panel. If I have a fire, all the firefighter have to do is open the 125 Amp main breaker at my service meter that will kill all the power to the whole house dropping out the relay that was passing DC power to my inverter. Simply control circuit that any Electrical person can understand . But it takes a Doctorate degree in Psychology or BS to make a Hayward City Permit Person understand. I'm still not Net Metering till I get my permit , but I'm enjoying low electric bills even with no credit back from the Utility company. The high peak days are Satuday's... Laundry day.

 

[OffGridInTheCity]

I saw this sentence in the link article - ".....That means less than 80 V in less than 30 seconds within the array boundary,...."

Just for discussion (my panels were permitted and I don't plan changes at this point)....

Does this mean that if I were to rewire my 3s (90-110v) down to 2s (60-80v) - e.g. fall below the 80v threshold - then I wouldn't need to worry about NEC on this? Just curious as 2s would still be high enough to charge my 48v battery bank.

 

[J_Mack58]

I saw this sentence in the link article - ".....That means less than 80 V in less than 30 seconds within the array boundary,...."

Just for discussion (my panels were permitted and I don't plan changes at this point)....

Does this mean that if I were to rewire my 3s (90-110v) down to 2s (60-80v) - e.g. fall below the 80v threshold - then I wouldn't need to worry about NEC on this? Just curious as 2s would still be high enough to charge my 48v battery bank.

You good OGITC, I think this only applies to new installs. The city not going to drive around looking this roof-top solar violation. There is no money in it for them, only the manufacturers of the so call "Rapid Shutdown Devices". But then again if these manufactures line the city pockets with money then look out!

 

[J_Mack58]

I researched the solution to comply with NEC 690.12 It will cost me $50 per panel plus $60 for a transmitter. I have to do this on my 14 Panel system. There is a box with a contactor that you plug your MC-4 plugs into . There is a transmitter that runs on ac that has like a current transformer that goes on you PV+ or PV- line. They transmit a signal over the DC line that is received by the box on your solar panel to close the contactor and as long as your AC is good you can have DC from your panels/ Basically $760 for me to comply . Gotta do it, rules are rules.

Recievers:
https://thepowerstore.com/ap-system...MIzojTpqja9wIVMMLCBB13FQhPEAYYASABEgInIfD_BwE

Transmitter:
https://www.ecodirect.com/APsmart-S...MIzojTpqja9wIVMMLCBB13FQhPEAYYAyABEgK8GfD_BwE

 

[floydR]

From the links $26.95 x 14 = $377.30 + $48 = $425.30 did the prices just change or does tax & shipping cost $300?
Later floyd

 

[J_Mack58]

From the links $26.95 x 14 = $377.30 + $48 = $425.30 did the prices just change or does tax & shipping cost $300?
Later floyd

Ha! I wish I was getting that model actually the 14 I have to get are:

APSYSTEMS, RSD-D-15, PV MODULE RAPID SHUTDOWN COMPLIANCE SOLUTIONS
​

• Model: RSD-D-15
• Manufactured by: APSystems
• Condition: New

Estimated Delivery: May 13th - May 19th

• In Stock

Price: $56.91

 

[cak]

I agree that these rule are a challenge in both expense and failure points. It has also been fueling the shift to microinverters on each panel which I have mixed feelings about. From my understanding and talking with some of the code folks through my day job. The main reason for the panel level under 80vdc is that if the firefighters were to be cutting through your roof in the course of fighting the fire and hit one of the DC panel wires before your string cutoff breaker assuming the panels are still in the sun(unlikely with smoke from fire) then there would be high voltage protentional from short circuiting the solar panel wires. I hope that made sense.

 

[J_Mack58]

I agree that these rule are a challenge in both expense and failure points. It has also been fueling the shift to microinverters on each panel which I have mixed feelings about. From my understanding and talking with some of the code folks through my day job. The main reason for the panel level under 80vdc is that if the firefighters were to be cutting through your roof in the course of fighting the fire and hit one of the DC panel wires before your string cutoff breaker assuming the panels are still in the sun(unlikely with smoke from fire) then there would be high voltage protentional from short circuiting the solar panel wires. I hope that made sense.

You made sense cak, if I was a firefighter here is some common sense I would use. I’m not cutting through any metal pipe running across anybody roof with an axe be it electrical, water or gas. I guess I‘m too real world as I do things and not engineer concept things. So if I put 10 solar panels on my roof in a string and neatly clip and tie-wrap all the conductors directly in line with the junction box on the solar panel that’s about 8 inches (200mm) under the panel the only way a solar panel conductor can be cut is the firefighter cuts through my solar panel. Make it a rule, firefighter don‘t be taking your axe directly to a solar panel, so the danger is when the conductors exit away from the array. There I would easily give them a DC rated two pole relay that opens when the firefighter cuts of the power at my main. Cheap , Simple and Done. At my day job we comply to SIL 2 and SIL3. SIL = (SAFETY INTEGRITY LEVEL) so two relays in series to have some insurance that contacts open. Nothing against you cak but that voltage level is BS, within 30 seconds?? They did all that study to come up with a code where with no study I can give them zero voltage in less then a millisecond.

 

[Korishan]

This is what I'd use:

And one for the Pos and one for the Negative. The Firefighter walks up, opens the box, and yanks the bridge out of the contacts. There'd be no arcing from one terminal to the next as they are too far apart, and the handle is highly insulated

 

[Oberfail]

If a fire ever breaks out and my solar panels are in the way, just break them, throw large rocks on it, hit them with a Axe or whatever. Large scale, thats way cheaper and economical to do, then to add more and more devices to solar panels.

 

[Korishan]

If solar panels are possibly adding to an electrical fire, then having the above will drastically help. As in, maybe you or a neighbor will know to pull those disconnects before the fire department shows up.
Also, having those disconnects should be part of the build anyways. There is absolutely zero way that those can fail, unlike some types of disconnect switches.
If not going with those above, something like this would work too. And these Solar Cut-Off switches must be clearly marked that that's what they are for.

Something like this a fire fighter would look for anyways before they go cutting wires. They really don't want to go cutting wires if it has the potential of causing more/worse fire.
For example, let's say you have a fire in the garage. The FF will go and disconnect power from Mains. If they see solar panel installation, they aren't going to want to take an ax or bolt cutters to the wires, especially on a sunny day, as cutting into the wires could potentially cause the wires to melt together or with the ax/cutters, causing a dead short, and thereby heating the wires up and possibly starting a fire elsewhere.
If they see the On/Off box above, they'll throw that before they do any other type of drastic measures. Cutting wires is the last thing they'll want to do.

 

[gpn]

If solar panels are possibly adding to an electrical fire, then having the above will drastically help. As in, maybe you or a neighbor will know to pull those disconnects before the fire department shows up.
Also, having those disconnects should be part of the build anyways. There is absolutely zero way that those can fail, unlike some types of disconnect switches.
If not going with those above, something like this would work too. And these Solar Cut-Off switches must be clearly marked that that's what they are for.
View attachment 27479
Something like this a fire fighter would look for anyways before they go cutting wires. They really don't want to go cutting wires if it has the potential of causing more/worse fire.
For example, let's say you have a fire in the garage. The FF will go and disconnect power from Mains. If they see solar panel installation, they aren't going to want to take an ax or bolt cutters to the wires, especially on a sunny day, as cutting into the wires could potentially cause the wires to melt together or with the ax/cutters, causing a dead short, and thereby heating the wires up and possibly starting a fire elsewhere.
If they see the On/Off box above, they'll throw that before they do any other type of drastic measures. Cutting wires is the last thing they'll want to do.

As a former structure (and wildland) firefighter I generally agree with this post! On a building fire we had at least one person assigned to shutting down all the utilities. Electical and gas were our main priorities with electrical being first. If the gas (NG or Propane) bursts a pipe somewhere we can shield ourselves with water to avoid the danger but spraying water on electricity is sketchy! Sometimes it was nearly impossible to find electrical shutoffs on older apartments or houses. That was a real pain.

 

[cak]

Something like this a fire fighter would look for anyways before they go cutting wires. They really don't want to go cutting wires if it has the potential of causing more/worse fire.
For example, let's say you have a fire in the garage. The FF will go and disconnect power from Mains. If they see solar panel installation, they aren't going to want to take an ax or bolt cutters to the wires, especially on a sunny day, as cutting into the wires could potentially cause the wires to melt together or with the ax/cutters, causing a dead short, and thereby heating the wires up and possibly starting a fire elsewhere.
If they see the On/Off box above, they'll throw that before they do any other type of drastic measures. Cutting wires is the last thing they'll want to do.

I agree with this and the main argument I have heard for why the shutoff needs to be at each individual panel is that string shutoffs like these mean any wires AFTER the cutoff switch but all the wires between the panels and the cutoff are still energized and could be shorted if the solar is in sun. Personally I think that risk is incredibly low but I guess when safety is at play the lowest common denominator is what the code is written for.

 

[Dr. Dickie]

Wouldn't a combiner box with fuses satisfy that requirement? I have a combiner box at my array (since I am 2S on each string should be below the 80V requirement). Each string is fused right there at the array in the combiner box. So there is a disconnect right there, though there is no way anyone would not understand how and where the power is run.

 

[J_Mack58]

This is what I'd use:
View attachment 27477View attachment 27478
And one for the Pos and one for the Negative. The Firefighter walks up, opens the box, and yanks the bridge out of the contacts. There'd be no arcing from one terminal to the next as they are too far apart, and the handle is highly insulated

Tough code they want the power off within 1 foot of the Solar Panels. I drove around the neighborhood and I see shiny stainless steel disconnects with big red handles. And now they said those are from 2014 Code and we can't do it now. Power must be off before the firefighter hit the roof.

 

[J_Mack58]

If solar panels are possibly adding to an electrical fire, then having the above will drastically help. As in, maybe you or a neighbor will know to pull those disconnects before the fire department shows up.
Also, having those disconnects should be part of the build anyways. There is absolutely zero way that those can fail, unlike some types of disconnect switches.
If not going with those above, something like this would work too. And these Solar Cut-Off switches must be clearly marked that that's what they are for.
View attachment 27479
Something like this a fire fighter would look for anyways before they go cutting wires. They really don't want to go cutting wires if it has the potential of causing more/worse fire.
For example, let's say you have a fire in the garage. The FF will go and disconnect power from Mains. If they see solar panel installation, they aren't going to want to take an ax or bolt cutters to the wires, especially on a sunny day, as cutting into the wires could potentially cause the wires to melt together or with the ax/cutters, causing a dead short, and thereby heating the wires up and possibly starting a fire elsewhere.
If they see the On/Off box above, they'll throw that before they do any other type of drastic measures. Cutting wires is the last thing they'll want to do.

Stainless Steel model and on the roof was old code.

 

[J_Mack58]

The way they want the code satisfied is, a transmitter transmits on the DC line of your Solar array (negative or positive line it does not make a difference) a signal to receivers on ever solar panel that control a relay that close when the transmitter is on. This transmitter is ran off your main so when the firefighter cut the mains off, the transmitter stops transmitting and the contacts open. I just submitted a proposal to the city since my panels highest voltage is 37 and the code says the voltage needs to be knocked down to 80 volts or less in 30 seconds, Two panels in series would be 74 volts, I want to install one receiver for two panels cutting my bill for this code in half. Waiting to see if that will fly.

 

[J_Mack58]

Meanwhile I'm letting the solar panels pay "up front" for the extra safety devices for firefighters.

 

[Korishan]

Wow, that is interesting. I hadn't heard of the remote relay cutoff before. Kinda makes sense, I suppose. But a lot of extra wire to run. At least you should be able to just parallel all the relays if you have to go this route.
I'm gonna guess that the voltage required for the relays is gonna be 24VAC. This is a common power source used in irrigation and is very easy to get a hold of. Or, if they don't actually specify the power supply/relays, then I recommend going with the 24VAC units. Most automotive relays will work up to 120VAC and something like 5A. So using a 24VAC trigger source should be fine.

 

[J_Mack58]

Wow, that is interesting. I hadn't heard of the remote relay cutoff before. Kinda makes sense, I suppose. But a lot of extra wire to run. At least you should be able to just parallel all the relays if you have to go this route.
I'm gonna guess that the voltage required for the relays is gonna be 24VAC. This is a common power source used in irrigation and is very easy to get a hold of. Or, if they don't actually specify the power supply/relays, then I recommend going with the 24VAC units. Most automotive relays will work up to 120VAC and something like 5A. So using a 24VAC trigger source should be fine.

No extra wires to run, just plug the device in parallel with your solar panel. To close the relay they must be using the DC from the solar panel. I'm gonna search some youtube videos to get the fine details. If my theory is right then at night the array will be all disconnected as the sun come up and the panels start to generate a energy there must be a level of voltage and current that makes the receiver come on and maybe just maybe the relay is solid state. Still waiting on my answer to buy 5 or 10.