How would you do this?

[bjp_ne_elec]

Need a WP Disconnect for a small A/C unit that is 240V/20A. Obviously it's on an outside wall and the wall is going to be finished.

Running NMB from panel to wall, and then what I'm struggling with is how I make the penetration to the outside and terminate in the disconnect. I know you can't run Romex NMB to the outside - so what would you do - put it in a PVC nipple. If it was exposed inside, I would run EMT with an LB to get through wall in to the disconnect - but everything needs to be concealed behind the sheetrock.

Keep in mind my experience is heavy commercial in my past life, so I probably ask a lot of stupid questions as I work to learn more about the differences in residential, and light commercial.

Thanks

Brett

[allenwayne]

Having installed countless amounts of A/C disconnects without any type of conduit nipple,I can`t see a problem.I use a simple plastic snap fastener type NM connector on the back KO.Since 99.9 % of our homes are stucco finished I install the disconnect on rough in, that way the disconnect doesn`t sit cock eyed on the finished surface.

[stickboy1375]

I also just use a snap in bushing, but I install duct seal around the bushing hole before fastening the disconnect to the house....

[iwire]

Brett, your right about the NM not being listed for outdoor use.

That said, it is very common for NM cables to be brought through the wall into the back side of a rain tight disconnect.

In some areas of the country the entire service panel is located on the outside of the home and NM cables are brought out to that through the back.

[Dennis Alwon]

Bob-- tell me how you can bring 40 circuits to a WP Main Breaker panel without violating the code other than putting a pull box inside and bring all the nm into it. My area is one of those areas where main panels were regularly installed outdoors with all the nm cables penetrating from either the wall or crawl space with a short PVC nipple (coupling and chase fitting). This seems to violate the NEC but is always accepted even in our toughest inspection counties. There is not enough connector knockouts,etc to deal with this, thus they let us do it. But this is probably another thread indeed.

[iwire]

Bob-- tell me how you can bring 40 circuits to a WP Main Breaker panel without violating the code other than putting a pull box inside and bring all the nm into it.

As far as what?

The NM being rated for outside?

[Dennis Alwon]

As far as what?

The NM being rated for outside?

No. In terms of article 312.5 C where no wire is attached to the box. The code gives exception to a conduit out of the top but not the back and certainly not 2" long nipples.

[iwire]

I would say using PVC nipples is a violation.

What I would expect to see is the NMs brought into the back of the panel with either single or twin NM connectors.

[Dennis Alwon]

That would be impossible when you have 40 circuits with range, dryer, water heaters, a/c or heat pumps, etc

[iwire]

That would be impossible when you have 40 circuits with range, dryer, water heaters, a/c or heat pumps, etc

Why?

Say 15 1/2" KOs for 30 two wire circuits and a few 3/4" for others.

In a 200 amp 40 circuit panel I bet I could lay those out.

Besides, I have seen pictures of outdoor residential panels done this way.

[Dennis Alwon]

Why?

Say 15 1/2" KOs for 30 two wire circuits and a few 3/4" for others.



That statement reminds me of the old joke "How do you get 10 elephants in a Volkswagon? 5 in the front and 5 in the back.

Every outdoor residential panel I have ever used (GE, ITE (Siemens), & Cutler Hammer) have one or two 2" knockouts in the back on the bottom. There is simply not enough space to do it. I can't even get a 40 circuit indoor panel wired without having to use most of the knockouts on the bottom. I would bet you can't do it. Hence, this is why they allow that installation here.

[iwire]

Every outdoor residential panel I have ever used (GE, ITE (Siemens), & Cutler Hammer) have one or two 2" knockouts in the back on the bottom. There is simply not enough space to do it.

You do have a uni-bit or hole saw?

[la2151]

Just had to comment. In CA, we use 2" romex connectors or other szs if need smaller, all circuits come in the back of the panel..yes it can be done.. thanks.

[iwire]

Just had to comment. In CA, we use 2" romex connectors or other szs if need smaller, all circuits come in the back of the panel..yes it can be done.. thanks.

That is likely an NEC violation.

Unless that 2" NM connector is listed for use with the number and size of cables you use it with.

[mdshunk]

That is likely an NEC violation.

Unless that 2" NM connector is listed for use with the number and size of cables you use it with.

Every time I see multiple cables through a large connector, it makes me a little angry. I take great effort to put the right cables through the right connectors, then some guys shortcut and put all of them in one big one. I did some research a while back to find out if any connectors were actually rated to do this. The best I came up with was Arlington's 1-1/4" connectors are rated for up to 9, 14-2's.

http://www.aifittings.com/c_20.htm

I found no 2" connectors rated for multiple cables.

[360Youth]

I like to use a caflex connector, with your hole from the house just large enough to accomidate the plastic screw in. It creates a non-metalic raceway through the exterior wall penetration and the factory gasket on the connector fits tight against the wall if the hole is drilled right. Doesn't work in all situations, but it does in most. The only issue is there is no actual clamp to the disconnect.:roll:

[Dennis Alwon]

You do have a uni-bit or hole saw?

I do have both bit and saw but lets think about your installation. How big a hole would you have to hack out of the siding or the band of the house in order to accomplish what you think can be done? The integrity of the siding would be aborted. How would you stop water from entering through that hugh slot you would have to make for all those connectors if you caould make them fit.

Now, take a whole saw 2.5" and drill three holes. In the panel put three 2" knockouts with your ko punch or whatever and install a 2" PVC TA or coup with a slip fitting. Nice snug fit, yep, but against the code. I still say there is no legal way to do it and I believe the 3 hole method does the least damage to the house. I guess the most important thing is safety and I feel that it is safe especially if you seal the holes with fiberglass or silicone.

[iwire]

I do have both bit and saw but lets think about your installation. How big a hole would you have to hack out of the siding or the band of the house in order to accomplish what you think can be done? The integrity of the siding would be aborted. How would you stop water from entering through that hugh slot you would have to make for all those connectors if you caould make them fit. .

I would prably cut a couple of slots vertically behind the panels gutter space.

I would seal the panel to the wall on the top and sides with silicone which os what I usally do.

I believe it was Peter D that had picture of a building under construction that the NMs entered the back of the panel.

It's a big country, different areas have different ideas of the right way to do things.

Here we keep our panels in the basement so this issue does not come up around here.

[stickboy1375]

The one thing I have a question about is, When is outside actually outside. Examples... If I cut a old work box into the outside of a house vs using a bell box, the old work box is legal correct??

http://www.aifittings.com/new_images/8091RIns3.jpg

How can this be leagal vs using a bellbox??? or a disco?

[Dennis Alwon]

The one thing I have a question about is, When is outside actually outside. Examples... If I cut a old work box into the outside of a house vs using a bell box, the old work box is legal correct??

How can this be leagal vs using a bellbox??? or a disco?

I don't think either is illegal.

[stickboy1375]

The reason I ask is I was reading EC and they had a write up on this situation...I'll try and find that issue...

[iwire]

I don't think either is illegal.

And the code section being violated would be what?

An electrical box inside an exterior wall facing outside does not have to be weather proof.

The interior of a building wall is not a wet location.

[Dennis Alwon]

And the code section being violated would be what?

An electrical box inside an exterior wall facing outside does not have to be weather proof.

The interior of a building wall is not a wet location.

I believe I was saying just that-- it is not illegal nor is the wire to the disco on the outside of the wall.

2 negatives make a positive

[Dennis Alwon]

The reason I ask is I was reading EC and they had a write up on this situation...I'll try and find that issue...

I bet the reason EC said that was because the wire in romex has no label as to whether it is thhn , thwn or whatever. After it leaves the wall of the building they must be considering that outside and thus illegal. That would make every residential panel box that is outside illegal. Just a guess.

[JohnJ0906]

I've installed plenty of disconnects with the Romex entering the back through a connector, and have never had any problem. That said, I usually run it in UF nowadays, that gives some leeway on the placement of the disconnect, I'm not locked in to an exact location for my disconnect.

[bjp_ne_elec]

Stickboy - what situation were you referring to? I think we have two situations being discussed - the first one is about getting NM in to the back of a Disco or Panel - and this has actually expanded to multiple NM's. The second situation is if NM is legal when it's "outside" - beyond the edge of the buildings finish - as it would be in the case of a Disco or Panel installed on an exterior wall.

I'm curious to see what the EC article is about. I have to start subscribing to that magazine. I did over 20 years ago when I was in this trade, and now that I'm back in to it, I think it's a good resource.

As far as 312.5 C, is ths concern that the cables could get pulled out? What's the reasoning with allowing it to be in to the top, but not the bottom? Really like to hear the reasoning. Anyone on this board sit on that panel?

Thanks,

Brett

[iwire]

I believe I was saying just that-- it is not illegal nor is the wire to the disco on the outside of the wall.

Dennis I am not following you, lets be clear.

1) NM into the rear of a rain tight disconnect?

Violation or not?

Code section?

2) An old work box is cut into the exterior wall of a building for a GFCI receptacle the box is finished with a wet location in use cover.

Violation or not?

Code Section?

[iwire]

After it leaves the wall of the building they must be considering that outside and thus illegal. That would make every residential panel box that is outside illegal. Just a guess.

Dennis this leads to another problem.

Where are you getting wet location breakers for use in that panel box?

My point is that it is a much discussed issue with no clear answer.

The fact is running NM into the back of exterior mounted boxes seems to be an accepted trade practice.

[Dennis Alwon]

Dennis I am not following you, lets be clear.

1) NM into the rear of a rain tight disconnect?

Violation or not?

Code section?

2) An old work box is cut into the exterior wall of a building for a GFCI receptacle the box is finished with a wet location in use cover.

Violation or not?

Code Section?


I do them both numbers 1 & 2all the time, however I think #1 is being turned down in some areas because the wire in nm cable is not suitable for outdoor use. # 2 there is no question that it is legal. There are no markings on the wire in nm cable that make it suitable for outdoor use( per #1)

Let me put it this way. If you stripped the nm cable and put it in a piece of carflex to the a/c unit, would that be legal. I don't think so because the wire is not marked with the wet location marks, such as thwn. How does the inspector know if it is legal. It is turned down around here. I think that once it enters the disco it is considered outside the building but I would never turn it down. (esp. since I am not an inspector). Is that clearer-- I am sorry I am bad with language.

[Dennis Alwon]

I totally agree with you Bob-- I think it is a bogus attempt to be righteous to the point of being in control. Everyone inspector who think it is illegal and worked in the field and have done the same thing for years without any problems. What is the big deal. I don't know. I see more outdoor panels with so much moisture inside them that they are rusting away. The wire is not the problem. I have seen nm cable buried in the ground for 25 years without a problem ( I don't recommend this) but you see what I mean. The breakers in some outdoor panels,that you mention ----their screws cannot be removed because of the rust on them.. Outdoor panels are not the way to go but sometimes a necessary evil.

[lbwireman]

Dennis I am not following you, lets be clear.

1) NM into the rear of a rain tight disconnect?

Violation or not?

Code section?

2) An old work box is cut into the exterior wall of a building for a GFCI receptacle the box is finished with a wet location in use cover.

Violation or not?

Code Section?


A phrase we hear frequently from inspectors in our area is "It's a gray area, subject to interpretation" (by the AHJ of course). We do this type of installation regularly and have never been written for it. That said, if we ever were, I'd be thinkin' J-box on enterior of wall with short as possible piece of conduit between J-box and disco (or whatever) on exterior of wall, transition from Romex to THWN in J-box, done.

[cloudymacleod]

why dont u use uf cable or just mc cable

[stickboy1375]

Several problems arise when installing an outlet box on the exterior of a building. If the box is flush, then it is entirely within the building, is not in a wet location and simply requires a weatherproof cover for 15 or 20A, 125 or 250V receptacle. In a damp location that is protected from the weather, the cover must be weatherproof when the receptacle is not in use. In a wet location, the cover must be weatherproof whether the receptacle is in use or not. Weatherproof covers are available for toggle switches.


The exterior wall of the building is the demarcation point between a wet (exterior) or damp (protected by an overhang) and a dry (interior) location. Where the box is on the surface, an FS or FD box is generally used, as these boxes have no openings other than for raceway or cable entries. If the wiring method is raceway, the threaded hub in the rear of an FDA box is used, and the conductors must be suitable for a wet location. One can check suitability by looking for a W in the insulation identification. The raceway must be sealed against the movement of warm moisture-laden air to the cooler air in the box on the exterior.

A matter of opinion
When using cable wiring, there are other issues to take into consideration. If the cable connector is threaded into the box hub, it is in a dry location. For example, according to some, if the conductors within the cable are marked THWN, then the cable can enter the wet location within the box. Others disagree on the basis that Type NM cable is permitted for dry locations only [334.10(A)(1)], without regard for the type of wire in the assembly. Still others feel that the interior of a properly covered and sealed box exposed to the weather is a dry location. This key question is whether the interior of a properly sealed and covered enclosure that is exposed to the weather is a dry location.
If the entry to a cast box is not through a hub, but through a tapped hole in the back of the box, then the NM cable connector is in a wet location, and these connectors are suitable for dry locations only unless indicated otherwise on the carton by a Underwriters Laboratories (UL) mark.


Exterior lighting included
Similar problems accompany lighting fixtures on the exterior wall. The issue of covering luminaires (fixtures) in specific locations appears in 410.4 (A): "Luminaires (fixtures) installed in wet or damp locations shall be installed so that water cannot enter or accumulate in wiring compartments, lampholders, or other electrical parts." This will generally require applying a bead of sealing material where the rim of the fixture canopy meets the wall surface to prevent rainwater from getting behind the fixture and entering the building wall. The luminaire manufacturer's installation instructions will generally include instructions for applying this weather protection.
A luminaire mounted on an exterior wall that is exposed to the weather is required to be marked "Suitable for Wet Locations." When wired with Type NM Cable, the same question arises: Can the wiring method that is permitted only for dry locations be used on a wet-location luminaire? In residential construction, it is almost universally done this way.
Unlike a box supplying a switch or receptacle, the box for a luminaire is not covered or sealed against the entrance of moisture except for the bead of sealing material installed where the luminaire canopy meets the wall. How effective is this, and how long will it last?

An even worse and too-common practice is to install a pancake (1/2 in. deep) box on the surface of the wall. This is a box suitable only for interior use in a dry location, but it is often installed in a wet location.
These may seem to be minor matters. Nit-picking, as it were, but when the EC is of one mind and the electrical inspector is of a different mind, then these matters are not trivial at all.
The main idea is to keep rainwater out of the building. Water leaking into the interior of wood frame walls may take some time to become evident, but by then is may have developed into a major structural problem.

[busman]

My recollection (I don't have the code here at the moment) is that the NM section does not mention damp OR wet locations. It just says "not subject to excessive moisture". I don't even know what that means. Certainly sounds like an AHJ question.

Mark

[ryan_618]

My recollection (I don't have the code here at the moment) is that the NM section does not mention damp OR wet locations. It just says "not subject to excessive moisture". I don't even know what that means. Certainly sounds like an AHJ question.

Mark
Correct...but in 2008 this changes to "wet locations".

[LarryFine]

I'd be thinkin' J-box on enterior of wall with short as possible piece of conduit between J-box and disco (or whatever) on exterior of wall, transition from Romex to THWN in J-box, done.
What would be the difference bewteen NM into a J-box and NM into a disco?

[LarryFine]

This key question is whether the interior of a properly sealed and covered enclosure that is exposed to the weather is a dry location. Inside a raceway, box, or enclosure is not a location; the location of the raceway, box, or enclosure is. The most watertight enclosure in the world is still a wet location if it is underground or exposed to rain.

Can the wiring method that is permitted only for dry locations be used on a wet-location luminaire? In spite of the above viewpoint, I do indeed use NM as you describe. The concessions I make are (1) that I make sure the wiring connections are inside the box, not the fixture canopy, and (2) that I always point the wirenuts upward.

[stickboy1375]

Sorry, forgot to point out that post #33, is a article I read from EC magazine...

[olmsted]

I'd just penetrate the wall, making sure the hole can accomodate a snap in romex connector. Attach a 50 amp non-fusible disconnect to the exterior wall & be sure to run a bead of Silicon around the top, and sides of the disconnect.
Make a 6 foot whip out of 3/4" sealtight terminate load then line and call it a day.