Why must boxes be installed flush with the surface?

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Nuts, you saw it too quick - I'm glad the "eye" joke didn't offend, I wasn't making a code-noticing reference, but Yoda's crosseyed in your picture. :)

Not to over-analyze my own joke or anything...
 
georgestolz said:
I wasn't making a code-noticing reference, but Yoda's crosseyed in your picture. :)
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Well, I must be cross-eyed too...I read 314.20 just before posting
lupe.gif
 
Mike03a3 said:
OK, I know this is a trick question, so I'll be waiting with interest to see where you take this.

One reason is to prevent the exposure of combustible materials to the interior of a box, which is also why the boxes don't have to be completely flush in a non-combustible surface like drywall.

I just purchased a bag full of these at big orange:

B1EXTB.jpg



We aren't doing any electrical work, but we are applying 1/4" pine bead board wainscoting around a room. So, I need to extend the existing boxes to fill the gap and eliminate the exposed wood.

Mike
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These things are good but I don't think that they fit into an adapter cover on a 1900 box. PVC box, yes, metal boxes, no.
 
georgestolz said:
So, with that in mind, what do you think about it?
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I think that the rules apply to a brick wall. ;)

The code is written for all situations, not just a box and a brick wall and I really don't want to see a list of exceptions under each code requirement.

Let me fill you in about the blown up box I posted.

An apprentice killed the power and installed the device (an occupancy sensor) he than turned the power on went back to the office and turned the switch on.

BOOOOMMM.

Even with the flush mounted box with the cover in place his hands where covered with black soot from the blast in the box.

IMO the NEC is correct to try to keep boxes as tightly closed as possible.
 
That photo looks like a LV old-work ring, not a box extension ring. It looks like the ears have been removed and the screws laid next to it. If this is not the case, I cannot figure out what the screw holes in the opposing corners are for.

Mark
 
If the boxes were not required to be within 1/4" can youimagine how far back some might end up? Anyone got some 8" 6-32's?
 
celtic said:
...and I just found that out like a day ago!

Seriously.

While reading some info on box adapters/extenders (because my AHJ is having a cow) - I saw this:
be1phot.jpg

I am used to using metal box adapters/extenders not plastic ones, and honestly, I thought the plastic was a bit cheap. I read something on the box to the effect of "prevents sparks" ..I don't remember exactly....put I DO remember the logic behind the phrase :D

Thanks Pierre. :)
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This style of plastic spark guard can even be used in multi gang boves and they will fit in a metal p ring.I used to use the metal ones but when I found these i switched in a heart beat no need to tape the set screws.
 
busman said:
That photo looks like a LV old-work ring, not a box extension ring.
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I was the foreman on the job, I promise you we do not use LV rings for 277 volt lighting circuits. :)

Here is picture of what was used.

Barestud1.jpg


4" x 4" x 2 1/8" box with MC clamps, 3/4" single gang ring and a Caddy H2-3 to connect it to the stud.

Of course those will be outlets but switches are the same with the addition of one cable in the bottom of the box.
 
bjp_ne_elec said:
Bob - what was the issue of why the box and device "blew up"? Was there a shorted wire to the box?
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The apprentice must have jammed the switched hot up against a sharp spot on one of the internal clamps.

Once he went and hit the switch to ON the show started.

At least he was not hurt, when he was walking up to tell me about the problem I saw his hands all black and thought he was burned.
 
iwire said:
I was the foreman on the job, I promise you we do not use LV rings for 277 volt lighting circuits. :)
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I think he was referring to Mike's picture. ;)

I can live with the answers I've recieved. There has to be a line somewhere, and...

j_erikson said:
If the boxes were not required to be within 1/4" can you imagine how far back some might end up? Anyone got some 8" 6-32's?
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...that does sum it up nicely. But I think some folks may have more of a desire for a securely attached box than a fear of any real combustion hazard (when they look at a box that would violate the section).

iwire said:
The code is written for all situations, not just a box and a brick wall and I really don't want to see a list of exceptions under each code requirement.
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That's a good point too. I'd agree that it's better to have a code that covers all similar situations with a broad brush, to leave room for things that truly deserve extra ink.

So, from an enforcement (and actual installation) perspective, would you as an inspector or installer permit a variance in a block wall? Suppose the masons did you no favors at all, and mortared in 70% of the switches and outlets between a quarter and and full inch back. Would you require your crew (or require on inspection) all the affected boxes to have spark rings?

What I'm wondering is, would the magnitude of the problem inspire you to bend, or would you adhere to this section religiously?

Thanks for all responses, folks. :)
 
Mike03a3 said:
B1EXTB.jpg
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busman said:
That photo looks like a LV old-work ring, not a box extension ring. It looks like the ears have been removed and the screws laid next to it. If this is not the case, I cannot figure out what the screw holes in the opposing corners are for.
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These are indeed remakes of LV rings. The only difference, beside the missing screws and wings, is that the device holes are molded larger, so they don't get threaded by the device screws. Instead, they "float" until the device clamps them to the wall surface.
 
Sparks can travel only so far while still hot enough to cause damage.
The further back the box, the less distance they may have to travel to reach combustible material behind the brick wall. The extension collars help to mitigate this potential issue.

Another issue becomes the length of the conductors for splicing and maintenance.
 
georgestolz said:
So, from an enforcement (and actual installation) perspective, would you as an inspector or installer permit a variance in a block wall? Suppose the masons did you no favors at all, and mortared in 70% of the switches and outlets between a quarter and and full inch back. Would you require your crew (or require on inspection) all the affected boxes to have spark rings?

What I'm wondering is, would the magnitude of the problem inspire you to bend, or would you adhere to this section religiously?
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Giving this a little bump, just curious what some folks do when the you-know-what hits the fan. :)
 
georgestolz said:
Giving this a little bump, just curious what some folks do when the you-know-what hits the fan. :)
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Guess it would depend on the inspector.Jim and I know an inspector that wouldn`t care if there were 1000`s of boxes affected by the setback situation.I went through 100`s upon 100`s of inspections with him where we would trim and then the tile guys would come behind us and tile the kitchen back splashes.He would tag each and every inspection for no spark guard.Rather than spent 1/2 a day finding out which home would get tile(takes that long when your doing 15 20 trims a day in a fast paced sub division)I had all the tim crews install those cheap arlington spark guards and loooonnnnng 6/32`s they didn`t remove the device.It was cheaper to install the spark guards and screws rather than get 15 20 $30.00 tags.
 
georgestolz said:
So, from an enforcement (and actual installation) perspective, would you as an inspector or installer permit a variance in a block wall? Suppose the masons did you no favors at all, and mortared in 70% of the switches and outlets between a quarter and and full inch back. Would you require your crew (or require on inspection) all the affected boxes to have spark rings?

.
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I'd have no problem if the boxes were set back a little too far in a block wall. I don't think adding a spark ring would offer any added protection.

I think a lot of numbers in code articles are selected somewhat arbitrarily. (sp?) Like distance between suppports and connectors, box fill, etc. Not that the codes are not important, but bending them sometimes will not have adverse consequences.

If I inspected every job to strict code standards, I'd fail many more.
 
j_erickson said:
I'd have no problem if the boxes were set back a little too far in a block wall. I don't think adding a spark ring would offer any added protection.

I think a lot of numbers in code articles are selected somewhat arbitrarily. (sp?) Like distance between suppports and connectors, box fill, etc. Not that the codes are not important, but bending them sometimes will not have adverse consequences.

If I inspected every job to strict code standards, I'd fail many more.
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Wish you`d move to pasco county Florida and become my inspector :)
 
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