Fire at Michigan State Champs

[Jaci]

Originally Posted by Kevin Sevcik

You might be badly burned if the frame is hot, but Ohm's law plus physiology says you're extremely unlikely to suffer any injury from the electricity itself. Wikipedia says the resistance of wet skin is about 1 kOhms. So a 12V battery can push, say, 12 mA through you. The chart on that page notes that 12 mA of AC would be noticeable after a few seconds, but not deadly. It's important to note that DC is much less dangerous in this regard than AC. Unless you have wires connected directly to your heart[1], it takes a lot more DC to kill you than AC. If anyone is doubtful, I can hold a demonstration at Champs where I will bravely grab both terminals of a robot battery with either hand an suffer no ill effects.

Mind you there's plenty of other dangers from the battery, but they're all the fire, explosion, direct-short causing a welding arc sort.

TL;DR: The robot battery (and your car battery[2]) aren't going to electrocute you unless you stab a positive and negative wire from them into your heart. In which case you have plenty of other problems besides.

[1]I have before. It was weird.
[2]Had a dead battery once in college and got a jump from a doctor. He gave me the same electrocution warning. And he should know, because he's a doctor. I didn't argue because I wanted to get home.

That is a fair point, I should have thought a bit further before posting that last line. Looking back, I should have known a bit better[1]. Even so, I still stand that touching an electrically charged chassis is far from a good idea, even if it's just for peace-of-mind.

[1]I do a lot of work with electrical systems. Also got shocked by a 240 ~3-6A wall socket (for the second time) a few years ago, less than a fun experience.

[Karibou]

Originally Posted by DareDad

Because someone screwed up. As part of field setup, the fire extinguisher is removed from case 8 and put by the side of the field. I usually put it in front of the FMS at the center of the table or on the end of the table where the FTAs are hanging out.

It's quite apparent that extinguisher was still in case 8. I bet all the FTAs get an email this week.

Unless it changed this season, Michigan does not use the standard road case system that the rest of the country uses. There is no case 8, just a toolbox and a tote or two with the non-tool items that are usually in case 8 (paper towel glass cleaner, etc). I'm actually not sure where the fire extinguisher is stored with Michigan fields.

Disclaimer: I didn't do any events in Michigan this year, so it may have changed.

Originally Posted by rsisk

If there was a short with the frame, does this mean the frame isolation test during inspection was not done?

Or would this happen even if the frame isolation test passed?

Or maybe it happened after inspection? Wire coming loose during a match?

[Doug Frisk]

Originally Posted by Karibou

Unless it changed this season, Michigan does not use the standard road case system that the rest of the country uses. There is no case 8, just a toolbox and a tote or two with the non-tool items that are usually in case 8 (paper towel glass cleaner, etc). I'm actually not sure where the fire extinguisher is stored with Michigan fields.

You make a good point. Though the extinguisher that came out eventually did look like the standard CO2 extinguisher packed with the regional fields.

[RoboChair]

Originally Posted by DareDad

You make a good point. Though the extinguisher that came out eventually did look like the standard CO2 extinguisher packed with the regional fields.

That was definitely a dry chemical extinguisher, the CO2 kind would have dissipated much faster.

[Calvin Hartley]

Originally Posted by Karibou

Unless it changed this season, Michigan does not use the standard road case system that the rest of the country uses...

This is correct. (Though I am far from an authority on the topic, I've helped with a handful of event setup and teardowns.)

[FrankJ]

Originally Posted by Jaci

Even so, I still stand that touching an electrically charged chassis is far from a good idea, even if it's just for peace-of-mind...

You are aware your car has an electrically charged chassis? In the States we bond one leg of of our power to ground. Touching a charged chassis really isn't an issue. You don't want to use your body to complete the electrical circuit though.

Before using your extingisher on an electrical fire, you want to remove the inigtion source. Powdered fire extinguisher are messy. Never my first choice when other options are present.

[Kevin Sevcik]

Originally Posted by FrankJ

Before using your extingisher on an electrical fire, you want to remove the inigtion source. Powdered fire extinguisher are messy. Never my first choice when other options are present.

On the other hand, it's not like it's wise to be choosy beyond making sure the extinguisher is rated for your particular emergency.

"No, no, it's not going to spread that much. Let's wait and see if we can find the CO2 extinguisher..."

[FrankJ]

Originally Posted by Kevin Sevcik

On the other hand, it's not like it's wise to be choosy beyond making sure the extinguisher is rated for your particular emergency.

"No, no, it's not going to spread that much. Let's wait and see if we can find the CO2 extinguisher..."

I cannot argue with that.

[ctt956]

Originally Posted by Kevin Sevcik

On the other hand, it's not like it's wise to be choosy beyond making sure the extinguisher is rated for your particular emergency.

"No, no, it's not going to spread that much. Let's wait and see if we can find the CO2 extinguisher..."

Look closely to the right of the robot in the video. A volunteer in a black shirt brought a CO2 extinguisher, and you can see him pull the pin, while another volunteer(white shirt, towards the back of the robot) was holding a dry chemical extinguisher. As others have said, the dry chemical was applied to the fire; you can see the guy in the white shirt aim and discharge his extinguisher.

Originally Posted by James Juncker

...the first extinguisher had its safety pin break off when someone attempted to pull it rendering the extinguisher useless increasing the time it took to extinguish the flames.

This is probably why the dry chemical was used instead of CO2. After seeing the pin break, he decided it would be better to put it out with the powder than to let it burn to search for another CO2, if there was one. (Good idea.)