Detached Garage Code Issues after a Fire

H

hitehm

Senior Member
Location
Las Vegas NV
Our customer's detached garage had an electrical fire that started in the attic space and he wants to know if there were any obvious violations. The garage was built with the house in 1995. The garage is supplied by a 3 wire, 100A feeder inside the main switch panel in the main house on 1awg aluminum to an MLO panel in the garage. The feeder has NO ground wire run with the 2 hots and neutral and the N and G bars and not bonded inside the garage subpanel.

Violations:
1 - I know this was built under some 1990s code but the first violation that I'm guessing was code even back then is, being a separate building supplied by a feeder, there is no disconnect mean at the building. The feeder attaches directly to the MLO subpanel with not separate disco. It has more than 6 breakers btw so the 2-6 rule is not valid.

2 - I understand prior to 2008, 250.32.B.2 allowed the option to run the feeder w/o an EGC and use the grounded N conductor as the ground fault path back to the main panel. However, doesn't this require N and G to be bonded in the subpanel? Otherwise, how would a ground fault, let's say up in the attic space, make its way from the branch circuit EGC to the grounded N to clear the fault? In fact, all of the branch circuit ground wires terminate on the subs grounding terminal strip and, other than being connected to the building grounding system (GEC), they go nowhere after that. So they basically do nothing as far as EGC.

3 - The feeder conduit also has 2 branch circuits leaving the subpanel going back down the conduit, one to the gate motor and the other is unlabeled. I see no issue with feeders and branch cons in the same conduit but we couldn't find any junction box above ground where they would separate out those branch circuits. So is it buried under the concrete, or worse?

Any input agreeing or disagreeing or if more info is needed to determine this accurately would be helpful. I hate being that guy that calls out previous work without having all my facts straight.
 
I believe you're correct that lack of a main disconnect (6 or less) was a violation in the 90s, although I'm not so familiar with the history of that code section. Very common violation, even today.

You're correct in everything you say about violation 2.

None of the things you mention are an obvious contributing circumstance to a cause a fire. Perhaps they speak to the quality of rest the work, but that's up to the jury (metaphorically, at least).
 
hitehm said:
Yes, the fire investigator did officially determine it to be an electrical fire.
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But didn't determine any more precise cause?

If it is rather obvious the fire started at a junction/switch/outlet location you may not be easily able to determine exactly what went wrong but can at least assume a bad connection or some other similar component failure along with some and joule heating while under load was likely to be the cause.

A fire doesn't just start in localized area of some conductor/cable that is totally intact, if a long length of of conductor/cable has melted or discolored insulation then it very possibly overloaded or was subject to fault condition and/or has improper/non functioning overcurrent protection.

If it started in a luminaire, appliance, or other utilization equipment you possibly need to determine whether that item was installed and maintained properly before you can determine who/what was the real issue that caused the fire, yes the energy that caused it originated from an electrical source but the fire may or may not be caused by shoddy installation or maintenance. When a fire investigator says it was an electrical fire people that don't know any better always assume some electrician did something wrong but is not always the case, in fact I'd guess it is seldom the case if the installer was qualified to do that work. Is always the guy that thinks he knows what he is doing that comes in sometime later to fix or change something that compromises things.
 
kwired said:
But didn't determine any more precise cause?

If it is rather obvious the fire started at a junction/switch/outlet location you may not be easily able to determine exactly what went wrong but can at least assume a bad connection or some other similar component failure along with some and joule heating while under load was likely to be the cause.

A fire doesn't just start in localized area of some conductor/cable that is totally intact, if a long length of of conductor/cable has melted or discolored insulation then it very possibly overloaded or was subject to fault condition and/or has improper/non functioning overcurrent protection.

If it started in a luminaire, appliance, or other utilization equipment you possibly need to determine whether that item was installed and maintained properly before you can determine who/what was the real issue that caused the fire, yes the energy that caused it originated from an electrical source but the fire may or may not be caused by shoddy installation or maintenance. When a fire investigator says it was an electrical fire people that don't know any better always assume some electrician did something wrong but is not always the case, in fact I'd guess it is seldom the case if the installer was qualified to do that work. Is always the guy that thinks he knows what he is doing that comes in sometime later to fix or change something that compromises things.
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All true and I don't have the official report to see what exactly he determined. However, we've done a lot of other work on this property and I can say without a doubt a lot of the original work, - electrical, plumbing, mechanical etc, was done subpar. Improperly wired and ungrounded outlets, wrong size wiring/breakers, many lose connections, unsupported wiring and conduit to name a few. However, an electrical fire that cost thousands and really shook up the family with young kids no less, is a big deal that you should always get 100% right before making accusations.
 
Isn't it possible something in a metal box or enclosure faulted, and the path for that fault was through building materials (if conductive enough which maybe not in Las Vegas) and then through the earth to the main panel. The fault current would be low because of the poor conductivity, but even a 100-200 watt "heater" sitting there 24/7 could get rather hot.
 
An issue I see a lot, is too high of wattage in enclosed fixtures. Not so much of a problem now with LED’s, but back in that era, 100 watt incandescent bulbs in an enclosed fixture rated for 60 watt max. One got so hot, the plastic j box melted, burned the wires, and the fixture fell.
 
Over the years I have seen structural fires blamed on "electrical" as a "last resort" when no actual reason could be determined. (I know if two when there was no power on the structure). "Electrical" is often a scapegoat
 
augie47 said:
Over the years I have seen structural fires blamed on "electrical" as a "last resort" when no actual reason could be determined. (I know if two when there was no power on the structure). "Electrical" is often a scapegoat
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Yeah, I remember Mr. Coffee years ago had a fire issue. It was always blamed as an electrical fire.

Ron
 
augie47 said:
Over the years I have seen structural fires blamed on "electrical" as a "last resort" when no actual reason could be determined. (I know if two when there was no power on the structure). "Electrical" is often a scapegoat
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I was at an EC&M conference years ago where the presenter was showing excerpts from newspaper articles about fires. One headline was “Fire caused by use of candles due to the house having no electricity.”
 
hitehm said:
However, we've done a lot of other work on this property
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hitehm said:
Our customer's detached garage had an electrical fire that started in the attic space and he wants to know if there were any obvious violations.

2 - I understand prior to 2008, 250.32.B.2 allowed the option to run the feeder w/o an EGC and use the grounded N conductor as the ground fault path back to the main panel. However, doesn't this require N and G to be bonded in the subpanel? Otherwise, how would a ground fault, let's say up in the attic space, make its way from the branch circuit EGC to the grounded N to clear the fault?
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I would call item 2 a obvious violation, and negligence on the original contractor.
I come across those floating ground violations out in the burbs quite often, sheds, garages, even a pool house panel, and I always fix it first, it was never allowed by code and a regular breaker needs that to clear a ground fault to equipment ground.
 
WD40 said:
I would call item 2 a obvious violation, and negligence on the original contractor.
I come across those floating ground violations out in the burbs quite often, sheds, garages, even a pool house panel, and I always fix it first, it was never allowed by code and a regular breaker needs that to clear a ground fault to equipment ground.
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Agreed. And in this case, that missing bonding jumper rendered not just one, but every single EGC useless. If you had the option not to run an EGC with the feeders back then, I can't believe they didn't make sure they did option 2 correctly. Probably why the got rid of the option.
 
hitehm said:
However, doesn't this require N and G to be bonded in the subpanel? Otherwise, how would a ground fault, let's say up in the attic space, make its way from the branch circuit EGC to the grounded N to clear the fault?
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If what you are trying to get at is that that condition could have been the cause of the fire, I don't think so.

-Hal
 
retirede said:
I was at an EC&M conference years ago where the presenter was showing excerpts from newspaper articles about fires. One headline was “Fire caused by use of candles due to the house having no electricity.”
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News writers are the worst when it comes to explaining technicalities and will often report something that is at least somewhat misleading because they don't truly understand what they are writing about even if they did have correct information to work with. And it has gotten even worse with the AI that they may have helping them write some their content.
 
kwired said:
News writers are the worst when it comes to explaining technicalities and will often report something that is at least somewhat misleading because they don't truly understand what they are writing about even if they did have correct information to work with. And it has gotten even worse with the AI that they may have helping them write some their content.
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Anything I've ever heard the news report on, where I knew the operation, or the people involved, the news writers got lots wrong. And I don't mean just in matters of opinion, I mean like basic facts. Like what the company made, what kind of machine was involved, who got hurt and what their injuries were etc. Either news people are really dumb, or they put zero effort into their fact gathering
 
hitehm said:
We're not officially involved in the investigation. He just wanted our opinion if we see anything obvious.
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Be very careful with what you say, or you may end up involved in the litigation. For example, if you saw something that was obviously wrong, would you as the professional with specialized knowledge be obligated to bring it to the property owner's attention? Even if it wasn't in the scope of your work, if it was obviously wrong, why didn't you make the owner aware of the hazard? If you did bring something up to the owner and the work was declined, did you document it? If it wasn't documented, it didn't happen.
 
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