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#47907 - 01/29/05 06:00 PM how many recepts on load of GFI?  
Clydesdale  Offline
Member
Joined: Nov 2004
Posts: 138
today, i was talking with a coworker, and he said that you could only have a maximum of 3 recepticles on the load side of a GFI receptacle...this didn't sound right to me...this is in an office bulding in the kitchen area.


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#47908 - 01/29/05 06:16 PM Re: how many recepts on load of GFI?  
Electricmanscott  Offline
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Joined: Jan 2002
Posts: 1,457
Holden, MA USA
Not limmited by code. Some say manufacturers have limit. I have not seen any but I know it is not three.


#47909 - 01/29/05 09:13 PM Re: how many recepts on load of GFI?  
Clydesdale  Offline
Member
Joined: Nov 2004
Posts: 138
yeah it sounded like a load of crap to me..also...the structure is single story, wood framing. the same guy was saying that we weren't allowed to bore holes in the rafters and to lay the wires (12/2, 12/3)over the top of them. this also sounded like crap to me, but it was my first day, so I said:"ok, if that's how you want to run it fine with me." he said that the foreman(who i haven't met yet) didn't allow it...I was thinking that he didn't allow it because it took too long.

The whole thing is kind of sketchy, don't really know what to think yet.

also...the guy was saying that the boss didn't like 2 wires stapled stacked on top of each other, and to run them side-by-side on the 2x4...this also seems like a bunch of crap to me....

[This message has been edited by Clydesdale (edited 01-29-2005).]


#47910 - 01/29/05 09:40 PM Re: how many recepts on load of GFI?  
SolarPowered  Offline
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Joined: Jul 2004
Posts: 625
Palo Alto, CA, USA
Out of curiosity, were the rafters dimensional lumber, or the bottom chords of trusses?


#47911 - 01/29/05 09:44 PM Re: how many recepts on load of GFI?  
Clydesdale  Offline
Member
Joined: Nov 2004
Posts: 138
I am not sure, there were metal plate connectors on them.


#47912 - 01/29/05 09:59 PM Re: how many recepts on load of GFI?  
Northbayec  Offline
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Joined: Dec 2004
Posts: 27
San Rafael, CA U.S.A
Drilling through rafters or trusses is not advisable in that it greatly reduces the structural integrity of the roof and the building. Many GCs and engineers won't allow it. As far as recepts on the load side of a GFI I was always taught no more than 4 on the load side due to more of a chance of nuisance tripping. The bosses request on the stacking of wires, well he is the one who signs the check. [Linked Image]

[This message has been edited by Northbayec (edited 01-29-2005).]


#47913 - 01/29/05 10:07 PM Re: how many recepts on load of GFI?  
Clydesdale  Offline
Member
Joined: Nov 2004
Posts: 138
just did a search about drilling trusses...doesn't look like the boss is going to be very happy when he sees the holes.

[This message has been edited by Clydesdale (edited 01-29-2005).]


#47914 - 01/30/05 02:16 AM Re: how many recepts on load of GFI?  
SolarPowered  Offline
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Joined: Jul 2004
Posts: 625
Palo Alto, CA, USA
It sounds like you've already figured out what I was getting at...

It's OK to drill though normal rafters, but you really don't want to be drilling though trusses without permission and specific instructions from the engineer who designed them.

A normal rafter functions as a beam, which means that right in the center there's a dead area where there is very little stress. The top of the beam is in compression, the bottom in tension, and somewhere around the middle the force goes to zero. So it's OK to drill there, because it doesn't effect the strength of the beam.

A chord of a truss works differently. The whole chord is pretty much uniformly under compression or tension, depending on where it is in the truss. If you drill a 1" hole through a 2x4 chord, you've reduced it's strength by almost a third. That's a really bad thing.


#47915 - 01/30/05 10:16 AM Re: how many recepts on load of GFI?  
Electricmanscott  Offline
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Joined: Jan 2002
Posts: 1,457
Holden, MA USA
Stappling the wires side by side on a 2X4 will not give you the proper clearance from the edge of the wood that is required. There is no reason to not put two cables under a staple.


#47916 - 01/30/05 06:49 PM Re: how many recepts on load of GFI?  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
I just sounds that the contractor is being conservative in his practices, and there's nothing wrong with that!

GFI's are listed to pass the entire load rating through them. I suppose that you then infer from other parts of the code that would mean 9 protected receptacles in commercial applications (assuming 15 amp circuit OR GFI).
In residential applications, while the NEC has no limit, many areas have local ordinances.

As others pointed out, you aren't allowed to drill "engineered trusses." That is, the pre-made things with metal plates ("gang nails") at the joints. Conventional rafters are another story.
SO the boss wants wires on top? Fine; but remember that you may also have to run boards alongside the romex to protect it.

Finally, most staples have never been evaluated, by UL or anyone else, for their use. Don't be surprised...you've been mounting stuff with "unlisted" nails, screws, and anchors forever!
The ones that ARE listed -usually intended for use in staplers- usually limit "stacking" to two cables. The NEC prohibition on stapling "on edge" might also be inferred to limit the heigth of a "stack" of cable.
Once again, there's nothing wrong with the boss being conservative. Far better than working for a hack!


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