Office cubicle fire

[mgookin]

How do you know that it was a bad connection?

Because it caught fire?

 

[fbhwt]

210.21(B)(1) is for a single receptacle

There is a duplex receptacle the surge/power strip is plugged into

mgookin, I was thinking a single duplex, not a single receptacle.

 

[mgookin]

mgookin, I was thinking a single duplex, not a single receptacle.

that might be where the confusion is.
Duplex receptacle is not a single receptacle.

 

[ggunn]

How do you know that it was a bad connection?

Something someone said earlier in the thread. If the fire was electrically started (as opposed to the heater igniting something unsafely close to it) and the ampacity of the conductors was sufficient for the load, what else could it have been?

 

[charlie b]

So why does 210.21(b)(2) Maximum Cord and Plug Connected Load to Receptacle not apply. 210.21 Outlet Devices. Does not specify where the receptacle is, but 210.21(B)(2) tells me that "a receptacle shall not supply a total cord and plug connected load in excess of the maximum specified in table 210.21(B)(2)

210.21 talks about two kinds of outlet devices. It starts off with outlet devices that are lamp holders, then it goes on to outlet devices that are receptacles. But if you are not dealing with an outlet device, then 210.21 does not apply.

Let me ask you this: If you purchase a receptacle from the store, and place it on your bookshelf still in its original box, would 210.21 apply? No? Why not? Perhaps because it is not an outlet device until you install it at a point on the premises wiring system. The cubicle wall is not a point on the premises wiring system, so any receptacle installed there is not an outlet device, and we can walk away from 210.21.

I feel like I am repeating myself. I'd rather not do that. So if you see something flawed in my reasoning, please point it out. Let's try and figure out why we are seeing this differently.

 

[charlie b]

If the fire was electrically started (as opposed to the heater igniting something unsafely close to it) and the ampacity of the conductors was sufficient for the load, what else could it have been?

Perhaps it could have been a good connection but too much current being drawn through the receptacle, causing it to get hot and igniting something nearby.

 

[fbhwt]

Because it caught fire?

The fire was out by the time I got there, and it probably was a loose connection, loose connection = resistance = heat = fire. What I do know is a 15 amp receptacle, part of a cubicle that is hard wired to a 20 amp branch circuit had a 15 amp surge protector/power strip plugged into it and a portable 120v 1500w heater plugged into that caused the wiring to get hot because of a loose connection and caught fire. Now all I have to do is figure out how to prevent this from happening again.

 

[al hildenbrand]

Now all I have to do is figure out how to prevent this from happening again.

Change the cubicle furnishing rules to exclude any electric heaters?

Give employees moon boots and sweaters and change the dress code?

Turn up the thermostat?

 

[RB1]

Charlie,

An outlet is not limited to the premises wiring system. It is a point on a wiring system. Office furnishings may or may not include a wiring system as stated in 605.3. Even though it is the intent of the code that internal wiring of listed equipment need not be inspected at the time of installation, that doesn't mean that once it is installed it is not subject to the provisions of the code. There are load limitations applicable to these receptacles whether or not they are part of a listed assembly.

 

[iwire]

Charlie,

An outlet is not limited to the premises wiring system. It is a point on a wiring system. Office furnishings may or may not include a wiring system as stated in 605.3. Even though it is the intent of the code that internal wiring of listed equipment need not be inspected at the time of installation, that doesn't mean that once it is installed it is not subject to the provisions of the code. There are load limitations applicable to these receptacles whether or not they are part of a listed assembly.

Article 605 does not point us to any other articles to follow.

IMO the only load limitations from the NEC are contained in 605.8.

Beyond that it is an issue for the manufacturer and the listing requirements.

 

[al hildenbrand]

An outlet is not limited to the premises wiring system. It is a point on a wiring system.

This is an interesting point. The Article 100 Definition of Outlet does not include the word "premises," only the two-word term "wiring system".

And the definition does not exclude having an outlet in series with an outlet.

 

[stevenje]

1500 watt heater plugged into a loose fitting receptacle contact is inviting this kind of thing to happen no matter where it is at.

That is one of my biggest issues with those claims by the makers of certain electric heaters and their claim their product can't start a fire. The product itself may be well designed and have cool enough surfaces but 1500 watts through a weak link at the receptacle is the same regardless, and I have seen many melted down cord ends and receptacles associated with those things.

Likewise. The cord end is the weak link. Once it starts to overheat the wall receptacle is the next to go. I had a service call a couple of years ago, at a vacation rental, where the cord end had melted down so much that you could not pull it out of the burned out receptacle.

 

[iwire]

This is an interesting point. The Article 100 Definition of Outlet does not include the word "premises," only the two-word term "wiring system".

And the definition does not exclude having an outlet in series with an outlet.

So now you too want to end a branch circuit inside of listed equipment?:huh:

That is not so much interesting as it is crazy.hmy:

 

[fbhwt]

210.21 talks about two kinds of outlet devices. It starts off with outlet devices that are lamp holders, then it goes on to outlet devices that are receptacles. But if you are not dealing with an outlet device, then 210.21 does not apply.

Let me ask you this: If you purchase a receptacle from the store, and place it on your bookshelf still in its original box, would 210.21 apply? No? Why not? Perhaps because it is not an outlet device until you install it at a point on the premises wiring system. The cubicle wall is not a point on the premises wiring system, so any receptacle installed there is not an outlet device, and we can walk away from 210.21.

I feel like I am repeating myself. I'd rather not do that. So if you see something flawed in my reasoning, please point it out. Let's try and figure out why we are seeing this differently.

Charlie, sorry that I'm not seeing the forests for the trees so to speak, the way I'm looking at it is I have a piece of equipment (cubicle) rated 15 amp (receptacle) connected to a 20 amp branch circuit, I have a 1500w portable heater (cord and plug connected load) plugged into 15 amp receptacle. Table 210.21(B)(2) Maximum Cord and Plug Connected load to Receptacle.

"Premises wiring (system) Interior and exterior wiring, both permanently and temporarily installed. I see the cubicle as interior wiring and temporarily installed. Article 605.8 I read, I go to chapter 3, I read 300.1(B), I look up definition of "equipment", I look up definition of "device" A unit of an electrical system, other than a conductor, that carries or controls electric energy as its principal function. Could this be a "receptacle"?

 

[kwired]

The fire was out by the time I got there, and it probably was a loose connection, loose connection = resistance = heat = fire. What I do know is a 15 amp receptacle, part of a cubicle that is hard wired to a 20 amp branch circuit had a 15 amp surge protector/power strip plugged into it and a portable 120v 1500w heater plugged into that caused the wiring to get hot because of a loose connection and caught fire. Now all I have to do is figure out how to prevent this from happening again.

Ban the use of high power heaters. If 1500 watts is really needed at a workstation in such an office environment then maybe there is a HVAC issue or a window is open/broken out? Women that wear skirts/dresses and open type footwear it is understandable they may get cold feet or lower legs, a small radiant heater under the desk that only draws a couple hundred watts is pretty effective for that situation.

Likewise. The cord end is the weak link. Once it starts to overheat the wall receptacle is the next to go. I had a service call a couple of years ago, at a vacation rental, where the cord end had melted down so much that you could not pull it out of the burned out receptacle.

I wouldn't say the cord cap is commonly the problem - I think it is more of an issue with receptacle to cord cap contact. You see these problems the most with the cheap grade receptacles, but the higher grade ones eventually do wear out some and are not immune to this problem either. If it does start in the cord cap it can take out a higher grade receptacle as well. Another problem can be contact resistance in the receptacle to supply wiring connections, again cheap grade receptacles seem to have more issues, but installer error can still take out a high grade receptacle as well.

 

[mgookin]

I did a search but didn't find anything that related to this: single office cubicle connected to 120v 20 amp circuit, 15 amp power strip plugged into cubicle 15 amp receptacle, 1500w portable space heater plugged into power strip along with computer and monitor. Cubicle receptacle wiring at receptacle got hot and caught fire. Code violation 210.21(B)(2) Would 210.21(B)(1) also apply?

You're talking about maybe 1850W @ 120V. That's not enough to start a fire on a 15A receptacle if the receptacle is in working order and the wiring was proper.

I suggest you go around the office and inspect all the receptacles including checking the torque on the screws. Look for signs of overheating. If one was bad and the same guy/ company did them all, there's liable to be more like it.

 

[RB1]

iwire,

Article 605 doesn't need to reference other requirements. There is nothing in Article 605 that modifies the requirements of 210.12(B)(2). Using your reasoning, a Furniture Power Distribution Unit could be installed in an assisted living facility with a receptacle outlet located within 1 foot of a sink. The argument would be that GFCI protection is not required because this is part of a listed assembly and Article 210 does not apply.

 

[al hildenbrand]

This is an interesting point. The Article 100 Definition of Outlet does not include the word "premises," only the two-word term "wiring system".

And the definition does not exclude having an outlet in series with an outlet.

So now you too want to end a branch circuit inside of listed equipment?:huh:

That is not so much interesting as it is crazy.hmy:

No, this isn't a matter of what I want. I see this as a matter of what the text of the 2014 NEC is saying. What I am reading in 605 and Article 100 recognizes the wiring within a manufactured office furnishing as a "wiring system."

605.9 unambiguously uses the two-word term Receptacle Outlet. The Scope of 605 applies to "wiring systems", stated without the word "premises", which is consonant with the Article 100 Definition of Outlet.

This is crazy-making, yes, but it seems, to me, to be what is written.

Bob, where is it written that an equipment assembly of office furnishing partitions, with included wiring system assembled entirely in the factory (not on site, except for the two-foot max supply connection), CANNOT be a "wiring system" as used in the Article 100 Definition of Outlet?

Lastly, note that the 2017 NEC 605.9(C) passage introduces the defined term "receptacle" in place of the 2014 NEC "receptacle outlet".

 

[charlie b]

I concede that the word “premises” does not appear in the definition of “outlet.” I also see that the phrase “receptacle outlet” appears a couple times within article 605. These tend to weaken my argument, but I am standing by my interpretation. Here is where I think the OP and I are seeing the situation differently:

I see the cubicle as interior wiring and temporarily installed.

I don’t, and I think Bob agrees with me on this point. I see the cubicle as being a piece of equipment that is connected to the interior wiring. The strongest point I can offer in defense of this interpretation comes from 605.8. It talks about connecting the cubicle to the building’s electrical system. That tells me that it is not treating the cubicle as though it were itself part of the building’s electrical system.

Even though it is the intent of the code that internal wiring of listed equipment need not be inspected at the time of installation, that doesn't mean that once it is installed it is not subject to the provisions of the code.

I think it does mean that, and I think that it should. 90.2(A) says that the code applies to installation of equipment. It does not mention operation of the equipment.

Here again, the code cannot legislate against stupidity. Many table lamps that I see in hotel rooms include a receptacle. If a hotel guest were to plug in the heater mentioned in post #1, and if that causes the lamp to get hot and start a fire, the investigation is not going to conclude that the fire was the result of a code violation. It is going to say that the fire was a result of stupidity.

There are load limitations applicable to these receptacles whether or not they are part of a listed assembly.

I continue to disagree. Most homeowners, building owners, office managers, and cubicle-dwelling workers have one thing in common: they don’t keep a copy of the NEC at hand. The authors of the NEC don’t expect them to. Nobody is going to look up the code limitations before deciding what to plug into the receptacle that is built into the cubicle wall. And they should not be expected to. They should be expected to follow common sense, and not overload any receptacle.

 

[fbhwt]

Ban the use of high power heaters. If 1500 watts is really needed at a workstation in such an office environment then maybe there is a HVAC issue or a window is open/broken out? Women that wear skirts/dresses and open type footwear it is understandable they may get cold feet or lower legs, a small radiant heater under the desk that only draws a couple hundred watts is pretty effective for that situation.

I wouldn't say the cord cap is commonly the problem - I think it is more of an issue with receptacle to cord cap contact. You see these problems the most with the cheap grade receptacles, but the higher grade ones eventually do wear out some and are not immune to this problem either. If it does start in the cord cap it can take out a higher grade receptacle as well. Another problem can be contact resistance in the receptacle to supply wiring connections, again cheap grade receptacles seem to have more issues, but installer error can still take out a high grade receptacle as well.

There is a base order that reads: "Electric heaters of the portable type are not to be installed in any building before a fire safety inspection has been made by the Fire Inspector. Electric portable heaters to be acceptable shall meet a standard that requires a thermostat for heat control, and a tip over switch for automatic shut-off if accidentally knocked over". I am waiting on a report from base safety to see what the fire inspector had to say. These heaters are used all over base, we have problems every year with breakers tripping, this is the first fire I have heard of. I have suggested changing the 20 amp breaker to a 15 amp, at least when the breaker trips due to overload(because other things beside the heater were plugged in) an electrician will have to go reset the breaker. Hopefully the electrician will want to know why the breaker tripped and find out if the heater is approved.