Rooftop solar panels become new enemy of U.S. firefighters - Page 2

Exeric · 09-14-13, 08:18 PM

Actually, one thing they could do right away is make it mandatory that a grounding rod is installed at all fire hydrants and make it mandatory that the hoses have a grounding wire throughout their length that is attached to it. Of course that would work most for firefighters working from the ground. But it would be a start, along with fire fighters having rubber boots and gloves at solar sights.

Edit:
Another thought. For those working on the roof it would be good to have an electrically conductive head to toe suit, if that's possible. Make sure it is connected directly to ground at all times either through the hose, or back at the hydrant. The key in all cases would be extensive training for the fire fighters on how electricity works when there is both hot voltage as well as a hot fire.

where2 · 09-14-13, 09:35 PM

Whether or not the solar panels were on the roof, stop for a minute and think about the concept of fighting a fire in a warehouse that covers 6 acres (266,000 sq ft). That building has to be between 320' and 400' wide, in the shorter direction (using the parking spaces in front of the building as a crude sense of scale)

For those who are curious, drop these coordinates into google maps: 40.048769,-74.931426

stevehull · 09-15-13, 07:25 AM

There is already work looking at incorporating a mandatory panel by panel master turn off that can be easily identified and activated on the roof (big red button). Enphase is in discussion on how to turn off all units by one simple wire (or wireless).

DC, from each panel doesn't kill - but the AC, produced by the inverter at 60 Hz WILL kill. Only a few mA of 60 (or 50) Hz current causes the heart to go into ventricular fibrillation. Many amps of DC causes burns, but it does not instantly kill.

The reason this is important is that firefighters need to be able to turn off ALL units quickly and easily.

Steve

Ryland · 09-15-13, 12:40 PM

There is training on how to fight fires on buildings with PV, the most dangerous part is that they are slippery.

Why can't you put an ax or chain saw threw a panel even in full sun? if they have a micro inverter then the A/C output of the inverter is turned off when the power to the building is turned off and A/C power is never in the panel no matter what!

The chainsaws have insulated grips and carbide chains so cutting in to a panel shouldn't kill anyone, it will just ruin the panel that you cut, if it's a high voltage string then electrical code has said that you need a DC shut off near the panels.

On a large flat roof there is plenty of space around and under the panels to cut holes and last I heard then you are installing panels on a house roof and the panels match the slope you are required to leave some space open at some point to vent.

NeilBlanchard · 09-15-13, 08:12 PM

If the electricity mains is off, then the panels are off.

iamgeo · 09-15-13, 08:15 PM

Key word is "if".

Ryland · 09-15-13, 09:55 PM

Electrical code requires that the breaker box be within a set number of feet of the electrical meter so it's easier to find from the outside of the house, but if you pull the electric meter from the socket it cuts the power and cutting the power and gas to a building that is burning tends to be first on the list.

NeilBlanchard · 09-16-13, 07:08 AM

IF the mains in not off, then the grid is what will cause the electrocution.

stevehull · 09-16-13, 08:11 AM

Quote:

Originally Posted by Ryland

Electrical code requires that the breaker box be within a set number of feet of the electrical meter so it's easier to find from the outside of the house, but if you pull the electric meter from the socket it cuts the power and cutting the power and gas to a building that is burning tends to be first on the list.

Ryland, I wish this code were uniform in the USA and elsewhere, but sadly it is not. In many states, you can have a remote meter (often on a power pole) with a feed to a central distribution box with shut off. This box can be hundreds of feet away.

You are absolutely correct that pulling the meter does 100% remove the grid feed to the structure in question.

Read the attached to see the number of mistakes are present in firefighting language.

Dangers of Solar Panels

Here are just a few of the misconceptions . . .

- PV panels always energized
- 600 V DC (no mention of AC)
- panels take 7-10 days in the dark to be deenergized

Read the rest of the thread where others point out some (not all) of the inaccuracies, but mud starts flying with castigation of electrical engineers and such (sounds like our forum!).

Steve

Exeric · 09-16-13, 03:34 PM

Steve, you are misinformed. PV panels are always energized as long as the sun is on them, right up to the combination box. That is the source of the problem. Also, if there is any disruption in the physical protection of the panel or the wiring right up to first disconnect box then any standing water from hoses has the possibility of conducting the current to the fireman. This is electricity 101. It might pay to actually learn about these things before insinuating yourself as an expert and saying that electrical engineers agree with you. They don't.

09-14-13, 08:18 PM	#11
Exeric Apprentice EcoRenovator Join Date: Aug 2012 Location: California Posts: 274 Thanks: 19 Thanked 37 Times in 28 Posts	Actually, one thing they could do right away is make it mandatory that a grounding rod is installed at all fire hydrants and make it mandatory that the hoses have a grounding wire throughout their length that is attached to it. Of course that would work most for firefighters working from the ground. But it would be a start, along with fire fighters having rubber boots and gloves at solar sights. Edit: Another thought. For those working on the roof it would be good to have an electrically conductive head to toe suit, if that's possible. Make sure it is connected directly to ground at all times either through the hose, or back at the hydrant. The key in all cases would be extensive training for the fire fighters on how electricity works when there is both hot voltage as well as a hot fire. Last edited by Exeric; 09-14-13 at 09:05 PM..

09-15-13, 07:25 AM	#13
stevehull Steve Hull Join Date: Dec 2012 Location: hilly, tree covered Arcadia, OK USA Posts: 826 Thanks: 241 Thanked 165 Times in 123 Posts	There is already work looking at incorporating a mandatory panel by panel master turn off that can be easily identified and activated on the roof (big red button). Enphase is in discussion on how to turn off all units by one simple wire (or wireless). DC, from each panel doesn't kill - but the AC, produced by the inverter at 60 Hz WILL kill. Only a few mA of 60 (or 50) Hz current causes the heart to go into ventricular fibrillation. Many amps of DC causes burns, but it does not instantly kill. The reason this is important is that firefighters need to be able to turn off ALL units quickly and easily. Steve __________________ consulting on geothermal heating/cooling & rational energy use since 1990 Last edited by stevehull; 09-15-13 at 07:35 AM..

09-15-13, 12:40 PM	#14
Ryland Master EcoRenovator Join Date: Mar 2009 Location: Western Wisconsin. Posts: 913 Thanks: 127 Thanked 82 Times in 71 Posts	There is training on how to fight fires on buildings with PV, the most dangerous part is that they are slippery. Why can't you put an ax or chain saw threw a panel even in full sun? if they have a micro inverter then the A/C output of the inverter is turned off when the power to the building is turned off and A/C power is never in the panel no matter what! The chainsaws have insulated grips and carbide chains so cutting in to a panel shouldn't kill anyone, it will just ruin the panel that you cut, if it's a high voltage string then electrical code has said that you need a DC shut off near the panels. On a large flat roof there is plenty of space around and under the panels to cut holes and last I heard then you are installing panels on a house roof and the panels match the slope you are required to leave some space open at some point to vent. Last edited by Ryland; 09-15-13 at 12:45 PM..

09-16-13, 03:34 PM	#20
Exeric Apprentice EcoRenovator Join Date: Aug 2012 Location: California Posts: 274 Thanks: 19 Thanked 37 Times in 28 Posts	Steve, you are misinformed. PV panels are always energized as long as the sun is on them, right up to the combination box. That is the source of the problem. Also, if there is any disruption in the physical protection of the panel or the wiring right up to first disconnect box then any standing water from hoses has the possibility of conducting the current to the fireman. This is electricity 101. It might pay to actually learn about these things before insinuating yourself as an expert and saying that electrical engineers agree with you. They don't. Last edited by Exeric; 09-16-13 at 03:58 PM..

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09-14-13, 09:35 PM	#12
where2 DIY Geek Join Date: Apr 2013 Location: Sunny Florida Posts: 401 Thanks: 74 Thanked 83 Times in 73 Posts	Whether or not the solar panels were on the roof, stop for a minute and think about the concept of fighting a fire in a warehouse that covers 6 acres (266,000 sq ft). That building has to be between 320' and 400' wide, in the shorter direction (using the parking spaces in front of the building as a crude sense of scale) For those who are curious, drop these coordinates into google maps: 40.048769,-74.931426

09-15-13, 08:12 PM	#15
NeilBlanchard Journeyman EcoRenovator Join Date: Dec 2009 Location: Maynard, MA Eaarth Posts: 383 Thanks: 78 Thanked 39 Times in 32 Posts	If the electricity mains is off, then the panels are off.

09-15-13, 08:15 PM	#16
iamgeo Apprentice EcoRenovator Join Date: Aug 2010 Location: Lakehills, Tx Posts: 168 Thanks: 4 Thanked 10 Times in 9 Posts	Key word is "if".

09-15-13, 09:55 PM	#17
Ryland Master EcoRenovator Join Date: Mar 2009 Location: Western Wisconsin. Posts: 913 Thanks: 127 Thanked 82 Times in 71 Posts	Electrical code requires that the breaker box be within a set number of feet of the electrical meter so it's easier to find from the outside of the house, but if you pull the electric meter from the socket it cuts the power and cutting the power and gas to a building that is burning tends to be first on the list.

09-16-13, 07:08 AM	#18
NeilBlanchard Journeyman EcoRenovator Join Date: Dec 2009 Location: Maynard, MA Eaarth Posts: 383 Thanks: 78 Thanked 39 Times in 32 Posts	IF the mains in not off, then the grid is what will cause the electrocution.