Entry Above Live Parts?

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busman

busman

Senior Member
Location
Northern Virginia
Occupation
Master Electrician / Electrical Engineer
I seem to remember that the code addressed entries into raintight enclosures not being above the lowest part of live parts, but I can't find it.

Thanks,

Mark
 
weressl said:
The 312.2(A) calls for specific method of entry, but does not prohibit entries above live parts.
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I have learned from the Internet that some inspectors in some jurisdictions prohibit entry above live parts. I never heard of that in my career, except in reading it on the net. This hasn't been my experience with inspectors.

Functionally, I try to limit entry above live parts when possible. From doing mostly service, I have learned one thing... everything will eventually leak.
 
mdshunk said:
I have learned from the Internet that some inspectors in some jurisdictions prohibit entry above live parts. I never heard of that in my career, except in reading it on the net. This hasn't been my experience with inspectors.
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You have got to be pulling our collective leg!!!! Please elaborate, the details as to why should be hilarious.
 
sandsnow said:
You have got to be pulling our collective leg!!!! Please elaborate, the details as to why should be hilarious.
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I'm not sure what you mean. I never was prohibited from entering an enclosure above live parts as long as the right fittings were used. That's all there is to the story. I never knew this was an issue until I read a few times on the net that some people aren't allowed to do that.
 
I have run into local Fire Dept requirements not to enter the top of master boxes at all.

To me, for that application it makes senses.
 
iwire said:
I have run into local Fire Dept requirements not to enter the top of master boxes at all.

To me, for that application it makes senses.
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Chemical industry practice:

...outdoor enclosure penetrations from the bottom of the enclosure, side enrty permitted, top entry prohibited. (All enclosures are specified as NEMA 4(X) and entries are to maintain that rating.)
 
Energize said:
What is a master box? I am not familiar with that term. Thanks!
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It gets mounted right above the apprentice box.

The master panel is the main FACP in larger buildings, and there are distributed panels that hang off that one.

A master panel can also refer to a main vioce evacuation panel in the ground floor lobby, with smaller similar panels on each floor.
 
Energize said:
What is a master box? I am not familiar with that term. Thanks!
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It's the device that transmits alarms to the Local fire dept.

The old school way was a basically a automated telegraph system.

There is a spring wound wheel with teeth that match the number of the box and open a close a contact which sends the box number to the FD.

box5111.jpg


The new way is radio frequency.

These ones are typical for my area, either the plan indoor unit or an outdoor unit with it's own pull box.

These ones can transmit 16 different zones.

transceivers.jpg


With either system (much more so with the radio box) water leaking in the top can be a problem.
 
mdshunk said:
The master panel is the main FACP in larger buildings, and there are distributed panels that hang off that one.
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In this area we may have a Main FACP with boosters and / or 'sub-panels' connected throughout the building but the Master Box is a separate item that is specific to that city or town. In my area some towns have none, some use the old telegraph type systems and there is at least 3 differing radio box systems in use in this area.

That said most of the FACPs we install are quite capable of calling out on phone lines to central stations if the town does not have a Master box system. :smile: (Even with a Master Box often we have two phone lines as well)

I recently learned some may be going to the Internet as a means of transmission. :confused:
 
iwire said:
I recently learned some may be going to the Internet as a means of transmission. :confused:
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I've seen some cellular setups on burglar alarms, but not on fire alarms yet. The Internet thing puzzles me a little, since central stations are UL approved and such, so I'm not sure how the UL would check out the Internet.

One thing I've come to realize over time is that there aren't any real good books on fire alarm stuff. All I've learned has been from putting them in and reading the manufacturer's literature.
 
mdshunk said:
I've seen some cellular setups on burglar alarms, but not on fire alarms yet.
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In this area I have never seen a radio master box that uses the cell phone network, I have seen them as you say for burglar.

The radio boxes here are stand alone proprietary systems and you have to use the system that particular town has gone with.

Some radio boxes transmit directly to the FD, others make their own 'cell network' by using the other same type radio boxes throughout the town to relay the message to the FD.

The direct approach means a 6' to 7' antenna mounted on the exterior of the building. The cell type use small rubber antennas.
 
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