FOLLOW UP ON CLOSED THREAD"UNIDENTIFIABLE SERIUOS PROBLEM"

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hardworkingstiff said:
I guess this stresses the importance of 300.50(F).

My guess is the conduits were not sealed, but I wonder if ductseal would have been enough to stop the vapors (I don't know what kind of pressure was developed).
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300.5 is for where there is a change of temperature in a raceway run, such as at the service where a conduit is between the meter can and panel that is inside in a heated or cooled environment, in the OP case where the conduit and panels or junction boxes are all out side 300.5 would not have applied, and yes you would be correct, the sealing is only to slow down the transfer of air between the two points not to totally prevent it, all it is supposed to do is prevent moisture build up as the air changes temperature.
 
hurk27 said:
300.5 is for where there is a change of temperature in a raceway run, such as at the service where a conduit is between the meter can and panel that is inside in a heated or cooled environment, in the OP case where the conduit and panels or junction boxes are all out side 300.5 would not have applied, and yes you would be correct, the sealing is only to slow down the transfer of air between the two points not to totally prevent it, all it is supposed to do is prevent moisture build up as the air changes temperature.
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You mentioned 300.5, but I don't know if you were responding to my mention of 300.50(F) or not. If you were saying that 300.50(F) does not apply, I would like to submit that section 300 is "Wiring Methods", and 300.50 is "Underground Installations", and 300.50(F) is "Raceway Seal".

Where a raceway enters from an underground system, the end within the building shall be sealed with an identified compound so as to prevent the entrance of moisture or gases, or it shall be so arranged to prevent moisture from contacting live parts.
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I would argue the lights are fed from an underground conduit system, and by the above mentioned code cycle they are required to be sealed. This section is not the one used for temperature difference, that one is 300.7, (at least the way I understand it).

If the conduits going to the lights had duct seal properly installed, I think there is a good chance this would not have happened. Since this was happening during/after a rain event, I would assume the water had something to do with it. If the conduit had 2' of cover, the pressure exerted by a 2' water column is right around 1 PSI. I would think well installed duct seal would be able to hold back 1 PSI of air pressure difference. The pressure was probably more than 1 PSI due to the ground resistance to gas escaping, but since this only happened when it rained, maybe the ground was not that much of a resistance.

Bottom line, I stand by my understanding that 300.50(F) requires these conduits to be sealed. I think this is a code section that is not enforced, just like 314.28 is often not enforced.
 
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hardworkingstiff said:
Thank you George!

That makes 2 faux pas' this week. I think I'm going to quit posting.

My apologies to all.
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No apologies needed as we are all here to learn, as I made a mistake also and didn't take the time to look it up but I was thinking you were referencing 300.7 and for some reason saw the .50 and turned it into .5 thinking that was where the 300.7 requirement was, what I get for thinking LOL:lol:

I think I just corn fussed myself:blink:
 
WorkSafe said:
Photo Ionization Detector, like a MultiRae

http://www.raesystems.com/products/multirae-plus
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The Multi-Pro by Honeywell I mentioned and linked to in post 20 also has the PID option as well as the data logging and black box recorder, as our company wants to know what happened and if we are following the rules of getting out if they go off, but the one you linked to sounds like it would be a lower cost option as data logging is not required for simple test as is the longer battery life that the Honeywell version gives (24 hours verses 14) the Toxi-Pros we use have a 9,000 hour battery life and are changed every 6 months for safety as they are our life savers if we get into a pocket of CO gas, but they are more of a personal monitor we have to always wear and they clip up by our necks on our orange FR level2 jackets as they have a loop there that they clip to, we are also required to bump them daily which down loads the data logger into the system network and calibrates them every morning when we bump them at a bump station which also has the calibration canisters of gas.

What I can't figure out is how in the world did they do the work we do without all these modern pieces of technology, carry canaries around LOL, well the saying goes at work "when you see the rats running you better run too"

Oh by the way its a large integrated steel mill and I work in the blast furnaces area as an MTE.
 
We probably have 20-30 of those MultiRae PIDs that was pictured on that link. The main issue we've had with those are the poor battery life, and the need for our calibration certifier to have a lot of spare sensors.

I believe Rae has a new line of decectors that self calibrate, all the data logging, etc.
 
hurk27 said:
No apologies needed ....
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Thank you hurk27!

The sad part for me is that this type of stuff has been happening a lot in the last couple of months. I'm starting to think I'm losing it (whatever it is, :lol: ).

Thanks again for your understanding! :thumbsup:

(PS, I still think duct seal would have probably adverted this issue and maybe it's not a bad idea?)
 
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