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wiring for solid masonry walls #15589
10/23/02 12:03 PM
10/23/02 12:03 PM
SvenNYC  Offline OP
Joined: Aug 2002
Posts: 1,691
New York City
My cousin's house in Cali, Colombia is made of solid masonry walls (brick and concrete).

Most construction down there in that city is made like this (including interior walls), which results in VERY solid buildings. Reinforced concrete (and rebar) is very big.

Now, when they did the wiring for his house, he tells me he chiseled narrow trenches into the wall in order to lay conduit. The electrician then fished through the pipe and into the device boxes. All of the pipe is then plastered over.

Is this an acceptable thing to do also here in the USA?

I went to a high-school here in NYC where all the walls (exterior and interior) were cinderblock and all the original wiring was in-wall so I'm assuming it is.

What's the proper device box for solid-masonry walls?

I know handi-boxes are used for surface mount conduit runs, but what would be the proper device for in-wall conduit runs? Somehow I doubt a handibox is listed for any type of in-wall use.

I didn't open any of my cousion's receptacles or switches to see the boxes.

For the record, Colombia uses NEMA standard wiring practices & devices, just like the USA (it's a 110-volt country).

Thanks guys!! [Linked Image]

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Re: wiring for solid masonry walls #15590
10/23/02 01:38 PM
10/23/02 01:38 PM
Texas_Ranger  Offline
Joined: Dec 2001
Posts: 2,409
Vienna, Austria
I've seen conduit in wall trenches plastered over in the US (VA I think, was some web site) and I think Home Depot in Brooklyn sells special UL listed masonry boxes.

Re: wiring for solid masonry walls #15591
10/23/02 02:44 PM
10/23/02 02:44 PM
txsparky  Offline
Joined: May 2001
Posts: 552
Magnolia,.Texas U.S.A.
The boxes used,no kidding,are called mason boxes.The bricklayer or mason,cuts a hole in the block for the box,sets the box and mortars it in.The electrician adds sections of conduit as the walls go up.(usually 30" pieces).This keeps the mason from having to raise the heavy blocks so far above their head to place the conduit into the web of the block.

Re: wiring for solid masonry walls #15592
10/23/02 02:55 PM
10/23/02 02:55 PM
WARREN1  Offline
Joined: May 2001
Posts: 176
Greenville, SC, USA
I am in the design portion of this business (that for background). I once did the design and followup inspections/observations for a project in Va. for the Univ. of Richmond. It was a major re-work of a mens dormatory. Almost all the conduits were chisled into stucco type walls, including receptacles, light switches, and to the light fixtures. The contractor did a great job of concealing the conduits. Boxes were generally 4X4 welded construction.
I think it would be very difficult in solid concrete. I would probably get it roughed-in, then let the concrete be poured.
Just my opinion.

Re: wiring for solid masonry walls #15593
10/23/02 04:52 PM
10/23/02 04:52 PM
SvenNYC  Offline OP
Joined: Aug 2002
Posts: 1,691
New York City
Thanks guys!!

Warren, yes, you're right. It is very difficult in solid concrete.

This was a very long time ago, but when my cousin (who is in his early 50s) told me about it, he says he had someone help him do the chiseling and it was a bitch of a job.

His house was existing construction that he was improving and adding to.

Back when they did this electrical installation, grounded three-conductor systems weren't yet very widespread, so his house is infested with those un-grounded two-pin NEMA 1-15R receptacles.

He's replaced a few over the years. At least the replacements are polarized...the originals weren't. :-)



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