New store - "old work" - Holdzit straps?

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bjp_ne_elec said:
Larry - which box supports are you referring to?
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The flat metal pieces others also call Madison clamps or straps. They're shaped somewhat like the Greek letter Pi. Like this: TT


macmikeman said:
Using a 90 deg flex connector inside a finished wall rings code alarm bells in my head, go read 350-20.
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I just did. From the '02 NEC:

350.20 Size.
(A) Minimum. LFMC smaller than metric designator 16 (trade size 1⁄2) shall not be used.

Exception: LFMC of metric designator 12 (trade size 3⁄8)
shall be permitted as covered in 348.20(A).

(B) Maximum. The maximum size of LFMC shall be metric designator 103 (trade size 4).

FPN: See 300.1(C) for the metric designators and trade sizes. These are for identification purposes only and do not relate to actual dimensions.


iwire said:
Oh don't forget to cut the receptacle yoke to fit inside the box ears.
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Good reminder!


roger said:
When using cut in boxes with madison straps is a 90 deg flex connector really inaccessible?
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Not to me: just unbend the supports and pull the box out of the wall. Even a junction box behind a kitchen cabinet is accessible.


iwire said:
Just not a fan of 'rear entry'.
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Now, we're gettin' personal!


bjp_ne_elec said:
By the way, how did "madison straps" get their name?
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My guess is that it is, or was, a company name, like Tomic and Mineralac.
 
OWB with sheetrock clamps ( Madison clamps is the name of the clamp up north, Down here we don't know any body by the name of Madison)
No connector needed if box is listed for AC or MC cable. why add another cost & labor wasting step to the install.
 
Don't you guys mean "Battleships"?
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As far as fire walls go, using old work boxes, installing pads on the boxes will be impossible. Why not roto-zip a wide hole, then a smaller hole for each box.... Leave the pieces you cut out screwed to the wall for "Others" to patch. "Patching, Fire-Proofing and Painting Not In Contract." If dealing direct with customer as opposed to a GC just inform them of the paramiters and tell the to hire a proffessional rocker and taper outfit.
 
LarryFine said:
My guess is that it is, or was, a company name, like Tomic and Mineralac.
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Are "Tomic" connectors still around? A few years ago I asked a couple of supply houses if they had any or could get some and I got the deer in the headlight look. Apparantly Tomic connectors never made it into the Wilmington, NC area.
 
quote" Article 350 in the 1999 NEC is for FMC not MC cable. Besides why would a 90 degree connector on a piece of MC cable be a violation? MC is not a raceway. There is nothing wrong with a 90 degree connector on MC cable.
__________________
Trevor "

Trevor, you are absolutely right, thank you for finding my error.
 
Firewall brings up an excellent point

Firewall brings up an excellent point

I should find out this Friday, but let's assume one of the walls (the one that seperates two stores) is a firewall. How would you handle the MC cable? I was just thinking of punching through the sheetrock just above the dropped ceiling line and fishing down the wall. It's odd know thinking back when I wasn't the "Master" how I dealt with "small details" (actually very important details) - but I was mostly on larger jobs where the architect and those you needed to run things by were around. It's amazing when you move to a smaller scale, of the things you really have to cover on your own.


THanks,

Brett
 
Found out this job is double-rocked ( 2 - 5/8") and to top it off, he wants Quad Receptacles. I don't see using OW boxes any longer. Anyone disagree?

Looks like I'm going to have to put my Dewalt DC550 to work buzzing holes next to the metal studs.

BRett
 
I would just run 1/2" EMT down the wall and surface mount the boxes. Let them paint it if they like.
 
Brett, being that the walls are double layers of 5/8 sheetrock, there is a better than average chance they are rated so fastening to the stud will be necessarry. Putty pads may or may not be necessary, (depends on the number of boxes in a given area) but sealing your MC or AC with a fire caulk should be done.

Roger
 
Actually Satcom has the best idea. Wiremold may be another option.

Roger
 
By running surface, it can easly be removed, most strip malls we do, the building owner wants us to surface mount.
 
I'm dealing with an inspector I've never dealt with before, and I didn't get a warm response when I mentioned OW boxes. But when we were finishing up the conversation, he made a comment that "you're allowed so many penetrations in a firewall" - so I took that as maybe OW's would possibly be allowable. I think I'm going to put together a layout and run it by him for "pre-approval". I don't want to cut OW's in between the studs and then have him reject them - as then is would be "patch city" in the rock.


I've never used Maddy clamps with double rock - have to see if the local supply house has them.

I like the EMT idea. Never used EMT on surface of sheetrock personally. I have to ask - how do you mount the boxes - directly through the rock into studs? As I've never ran anything surface mount on rock - in my own past experienses - are there any restrictions on how you anchor boxes or conduit to the rock. For mounting other than electrical - I personally love those plastic (not sure what they're officailly called) anchors that screw directly in to the rock. Just drive a #2 Phillips in to the rock and screw the bad boy home.

Thanks

Brett
Brett
 
Sure, if they will let you surface mount, go with that. It's easier and faster than fishing. If they haven't painted and you can see where the studs are just use 2" sheet rock screws and screw right to the studs. 1900 boxes and raised covers for those quads. Make sure the tenant agrees to surface mount in writing. Make sure they know it's not your job to paint conduit or to tape off receptacles for paint. Give the customer the options and let them make the decisions. See if these receptacles need to Meet ADA height requirements. Normally if you stay above 18" to center you are good ( check anyway ).
 
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According to the customer, the some of the receptacles are to be mounted at 48" (just above a work counter) and the others at 7'-8', as these are for LCD screens that he's going to hang there.

Have to ask - what is "ADA Height"? AHJ - is Authority Having Jurisdiction.

Growler - excellent suggestion about the painting of conduit and the taping off of receptacles. It's those finer points that could burn you, and again, I'm really green with this EC thing - so again, excellent tip!

I'm seeing almost a 50/50 split as to whether OW boxes would fly in the firewall. Some folks are saying "no, they can't be used" - while others are saying "they're fine" - and then I just get this look from the Inspector when I mention them, that didn't even want me to ask another question.

Anyone have any nifty ways of supporting multiple runs of MC? All my experience as a Journeyman was running either EMT or Rigid. The only thing I ever used flex for was for tails to drop-in light fixtures.

THanks,

Brett
 
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Brett, if the original walls have a UL design attached to them (you would need to see the original drawings for this design type) and you decide to mount the boxes in the walls, then to keep the assembly in line with the design type, the boxes would have to be attached to the studs (per UL) regardless of what any one says, even an inspector. These boxes can be OW boxes.

ADA = Americans With Disabilities Act

Roger
 
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bjp_ne_elec said:
Anyone have any nifty ways of supporting multiple runs of MC?
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Caddy (a division of Erico) and B-Line both have a lot of products for that.

Get some catalogs or find them on the web.
 
bjp_ne_elec said:
...[inspector] made a comment that "you're allowed so many penetrations in a firewall"
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You should determine if he is the AHJ on firewall penetrations (if you penetrate). An electrical inspector may not be the AHJ on the issue... may be the Fire Marshal.
 
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