Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

So we are in agreement? ;)

I clarified in my post right as you posted to make it clear to others where the requirements actually exist.

"Doing any of these things violates the UL listing, which in turn goes against the OSHA and NEC requirements to use UL devices per their recommended listings."

Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

Frank is awesome. He's very in tune with team issues and happenings. He reads CD and the like, too.

Can he stay, please?

-Nick

Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

In more seriousness, when you first Google "daisy chaining power strips", the very first thing that comes up is the Office of Compliance Guidelines, which talk a lot about the OSHA Regulations.

If you read carefully, they do agree that the main problem is drawing too much current:
But the reason this is such an issue is because people don't sit down and figure out how much load they are putting on the circuit, where their power is coming from, etc. So people do stupid things like Daisy chaining power strips and using 16/18 ports and attempt to draw way more than the allotted 15 or 20 Amps for that circuit.

How many times have you walked into a pit to see giant powered displays, 8 battery chargers plugged in, someone running a corded power tool, two kids working off of laptops someone running a compressor off of AC and 5 cell phones plugged in? Did anyone in the pit sit down and figure out the power draw? Probably not. Are they really drawing more than is allotted? Maybe not... But the point is no one figured it out.

And when people do dumb things, safety inspectors make rules in order to prevent the dumb things. It may not be exactly the right rule, but its a rule based on the majority of people. Yes FIRST people are smart (in general). But I've not been to a single competition where I heard anyone trying to figure out how much power they were drawing from the pit outlets (except when they blew the breaker!). So safety advisors make rules to attempt to help prevent issues before they happen. An electrical fire is NOT something we want to have to deal with. Is this rule exactly right? No. But can I see why they made it? Yes.

Teams do stupid things with power because it is easy. I've seen a team running battery chargers from an AC-DC converter that was plugged into their cart power strip, which was plugged into a DC-AC converter being run off of some sort of Marine battery. REALLY? Too many teams/people don't know the subtleties of AC power draw, thus OSHA makes rules to prevent the majority of them from doing stupid things. Thus... this "safety quiz"

*offsoapbox*

Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

Yes

Each of the individual receptacles are only rated for a few hundred watts. That's why they also say not to use them with space heaters. It should be easy to see why daisy chaining power strips with many small loads may not overload the overall rating, but may overload an individual receptacle.

Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

Okay, so, regulation (and Travis and Joe) say I'm wrong, and I'm fine with that. Clearly I am not an expert on OSHA and UL regulations.

However, if FIRST is concerned with making any actual improvement in electrical safety, they should mandate the installation of Anderson SB50 connectors on battery chargers. The potential to short a battery across aligator clips while charging is a HUGE fire risk. The way some teams charge their batteries with alligator clips into the battery connector means you're just milimeters away from a 600-Amp dead short of very very little resistance. All it would take is a bump or a tool to land on it. And it's really no better if the alligator clips are down on the battery terminals. It's still exposed and prone to a spark-throwing short circuit.

Let's stop playing safety theater and impose regulations that reduce actual serious risks, rather than preventing things that are likely to never happen.

Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

Oh no, not power strips!!! :ahh: :ahh: :D

As an electrician I understand where UL is coming from they are coming from but also know what goes on in the real world, do a piss poor job distributing power at large event and you better get used to lots of strips and cords. And the FM to be on your rear end screaming about shutting your event down.

Start running proper event power setups and provide pits with MWBC tri outlet boxes if they are serious about this issue.

Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

So, I guess our practice of plugging a power strip into itself to get free energy is now illegal?

Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

We did a quick measurement/survey at IRI several years ago. No team was seen to be using more than 10 amps; 2 was typical. There wasn't a lot of power tool use, though.

Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

Well I guess it is time to blow my horn.

In 2007 our team distributed an SB50 connection with wiring to rework over 1,300 chargers for that season. The effort came within an inch of getting the team the CMP UL Safety award, runner up instead. It generated the language in the safety manual and the safety animation about safe battery charging. Casual observations indicates that it increased safe charging behavior from about 35% pre-2007 to 85 or 90% now. That is based on some surveys we have conducted but not across every regional. Why it isn't mandated ? I don't know. I have seen several fires and put out a couple myself. Once I was standing in front of a pit, I saw the short and saw the alligator clips turn red to white hot and I stepped in pulled the cabling, for example. For the regionals we go to we survey the pits and rework chargers if permitted. We only have to do a handful a year now.

Re: FRC Blogged - Wireless Security, Karthik at TEDx and a Pop Safety Quiz!
 

Horn blowing, part II.

We have been working on creating a 'lean' operation for years. One of the big things that drive this is the number of exhibition events we do each year. Battery transportation, handling, maintenance, charging has been a big hassle but has gotten a ton better.

FRC batteries love a 2 amp charger better than the 6 amps allowed. Our 2 amp Deltran is perfect for competition but is not good for exhibition. Nor did we have a good 'lean' method for transportation. So we created a new battery management system.

As the FRC safety guidelines and OSHA rules exist, we can use our new system to move the batteries, but we cannot connect the new chargers unless FIRST provides us two more outlets. Practically speaking, that is OK, and we can live with that and just use the on-rack Deltran. It just puts batteries on the floor creating yet another type of hazard, just not electrical.

Here is an overview of the pit. Under the middle shelf is a 20 outlet power strip, 5 feet long, TrippLite.




Look under the bottom shelf and you will see a static 10 plug charging dock.



This is the new battery transportation and charging system. The interior is compartmented and cushioned.

• We daisy chained the power strips, violating the OSHA and UL rule. It is a dedicated application and we know what the power flow is. We don't have an engineering problem, just a rule problem.
• We could un-daisy chain it and send two cords out the chassis but we need a place to plug them in.
• We could cut the cords down and put them into a junction box and send one plug out the box. Cutting the cords breaks the UL approval on the strips.
• We could put in a duplex outlet in the chassis, plug the strip in and send the cord from the duplex box out of the chassis.

The cord is out the front temporarily. We are going to put a 2" hole with grommet on the back of the lid, left side, to exit to the left rear. We will do that with a Greenlee panel punch.



Another interior view



This is the original box



This thing is fantastic. It transports batteries very safely and very securely. When we are doing road show exhibition we setup in minutes.

Okay, not seen is a watt / amp meter we have in the rack. It is one of those things you get from Home Depot and you can move it around.

If we had to go to competition today and the venue provided one 15amp circuit, to be legal we use rack-power only, the battery box is transportation, we put batteries on the floor so we can trip over them. No power on the box, even though we know the current load.

My long term preference is to install a metered 'load-center' on the rack.
There are two options.

• install a real Square-D or Cutler-Hammer load center, UL approved
• install quad-outlet with a cord to plug into the venue and we plug our strips into the quad-outlet.

A cord with a quad-outlet is basically functionally the same as an outlet strip, but could be built with much higher quality components.

• Pro's - it can be built with high quality components
• Con's - it isn't UL approved but of unknown origin, possibly home built or better yet certified electrician built.

I am not in favor of teams building their own load center or simple duplex-outlet considering we still have other electrical safety issues out there. If they screw this up you are putting serious electricity out there.

I'd prefer that we find a high quality box that is UL approved and rated for this type of 'daisy chain' distribution root application.

Does anyone know of such a box ?