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toadf16

01:40PM | 06/04/07
Member Since: 06/03/07
3 lifetime posts
Bvelectrical
Hello,

I am installing a new subpanel in a finished garage. I have cut the drywall out between the studs adjacent to the main service panel. The subpanel is a 125A max main lug panel from Cutler Hammer. I am using a 50A breaker to power the subpanel, using 6/3 with Ground for the connection. I have drilled a 1" hole in the stud between the main and sub panels below the main panel. My questions:

1.) What is the code-approved method of supporting the 6/3 that runs through a 3/4" cutout on the bottom of the main panel? Since it is a finished wall, I am having difficulty figuring out how to get a 3/4" clamp installed from the bottom. I can only think to pop out a larger cutout and put my fingers through that to hold the clamp in the 3/4" cutout while I put the nut on. Can anyone recommend another code-approved approach?

2.) On my main panel, all of my home wiring runs are routed through the top of the panel in a large (2 1/2" I think) male nipple. I cannot tell if there is anything attached to the nipple or not. Should I run all of my new circuits in the subpanel through the same setup? If so, does code require any kind of riser above the nipple?

3.) I have read in some places that 6/3 can be protected with a 60A breaker. Is this the case? Are there any stipulations on when a 60A breaker can be used?

4.) Finally, on my florescent lighting install: I have installed old work boxes above where each light will go. There are 3/4" cutouts in the lights that I plan on running the pigtails through. Can I install 3/4" NM nipples through these holes and simply route the pigtails through them?

I would appreciate responses from anyone who is familiar with code pertaining to these issues. Thanks.

Nate

Tom O

02:12PM | 06/04/07
Member Since: 09/17/02
487 lifetime posts
Nate,

1. With a pencil, mark the wall where the panel cover ends at the bottom then remove the panel cover. If you're lucky, you can cut out enough drywall (don't go past the pencil mark) to slip a 3/4" connector into the panel from below. Alternatively, you can install the locknut on the outside of the panel & the clamping part of the connector on the inside. The third option is to drill a hole in the stud large enough to pass the connector through. Attach the connector to the cable then slip the whole assembly through the hole.

2. Running all the cables through a nipple is fast & easy. Unfortunately in this case it is not in compliance with the National Electrical Code. Cables must be secured to the cabinet with a connector. I usually pull all cables into the stud space, put connectors on them, tie a string to the end of each cable & shove them all back up into the stud space. Punch out the required # of knock outs and as you slide the panel into the hole, put one string in each knock out then pull the cables in once the panel is in the hole.

3. A #6 cable is good for 55 amps. Since 55 amps is not a standard size breaker, it is permitted to be protect the cable with a 60 amp breaker. Keep in mind that you have not gained an extra 5 amps of capacity, the maximum allowable load is still 55 amps.

4. Generally, surface type ceiling mounted fluorescent fixtures are usually wired without the boxes, the wire is just brought directly into the fixture. If the fixture is designed to be supported independently of the box, access must be provided to the box and a 3/4" nipple isn't going to work.

Tom

toadf16

02:49PM | 06/04/07
Member Since: 06/03/07
3 lifetime posts
Tom,

Thank you for your speedy response. I have some follow up questions:

"1. With a pencil, mark the wall where the panel cover ends at the bottom then remove the panel cover. If you're lucky, you can cut out enough drywall (don't go past the pencil mark) to slip a 3/4" connector into the panel from below. Alternatively, you can install the locknut on the outside of the panel & the clamping part of the connector on the inside. The third option is to drill a hole in the stud large enough to pass the connector through. Attach the connector to the cable then slip the whole assembly through the hole."

Perfect. It's the simple things we don't think of!

"2. Running all the cables through a nipple is fast & easy. Unfortunately in this case it is not in compliance with the National Electrical Code. Cables must be secured to the cabinet with a connector. I usually pull all cables into the stud space, put connectors on them, tie a string to the end of each cable & shove them all back up into the stud space. Punch out the required # of knock outs and as you slide the panel into the hole, put one string in each knock out then pull the cables in once the panel is in the hole."

I will use the method you mention. However, if it is not in compliance with the code, why are all of the electrical contractors using that method in my area (NE Oklahoma)?

Additionally, is it permissible to leave some sort of pull-string in the box to allow for future expansion? I have found it very difficult to fish into the attic through those small holes. It would make it easy to attach the NM cable to the string and simply pull through.

"3. A #6 cable is good for 55 amps. Since 55 amps is not a standard size breaker, it is permitted to be protect the cable with a 60 amp breaker. Keep in mind that you have not gained an extra 5 amps of capacity, the maximum allowable load is still 55 amps."

Understood. Good info.

"4. Generally, surface type ceiling mounted fluorescent fixtures are usually wired without the boxes, the wire is just brought directly into the fixture. If the fixture is designed to be supported independently of the box, access must be provided to the box and a 3/4" nipple isn't going to work."

I have already installed the lights. The lights are screwed into the ceiling and are covering the old work boxes. In the old work boxes, I have connected the NM runs and pigtails, and then dropped the pigtails into the lighting fixture through the knockout (with no fitting as of now). Is this acceptable? When you say there must be access to the box, do you mean the box must be visible and not covered by the light? If that's the case, how would you run the wire from the box to the light without it being visible?

Thanks again for your assistance.

Regards,

Nate

TimBonham

11:25PM | 06/04/07
Member Since: 01/09/07
197 lifetime posts
"I have already installed the lights. The lights are screwed into the ceiling and are covering the old work boxes. In the old work boxes, I have connected the NM runs and pigtails, and then dropped the pigtails into the lighting fixture through the knockout (with no fitting as of now). Is this acceptable? When you say there must be access to the box, do you mean the box must be visible and not covered by the light? If that's the case, how would you run the wire from the box to the light without it being visible?"

The code requires that boxes be accessible (no boxes hidden behind drywall, etc.). Often, though, inspectors will allow boxes like this if they have no connections in them (so if the NM cable came into the box, then came right out of the box into a knockout hole in the top of the light, and was connected inside the light fixture -- thus no break in the NM cable inside the hidden boxes). But since you mention pigtails, it doesn't sound like that is what you have.

If the inspector complains, you might be able to argue that the boxes are not 'concealed', they are accessible by removing the light fixture (just like normal ceiling boxes are accessible only when you remove the fixture. Bit of a stretch, but might work.

What you've done doesn't sound unsafe (provided you made sure the boxes are covered tightly so mice, etc. can't easily get inside to make a nest there). But you've made more work for yourself if you ever have to fix them. For example, if one of those pigtail connections ever comes loose inside the box, sounds like you will have to take the entire light fixture down just to tighten up a wire nut.

Tom O

01:45PM | 06/05/07
Member Since: 09/17/02
487 lifetime posts
As far as all those contractors running cables through pipes, I can only address the National Electrical Code and not local enforcement or the lack thereof (been waiting to use that "thereof" for a long time). There is a provision for running cables through conduit and into the panel, but it only applies to surface installations.

All unused knockouts in a panel must be closed, so a string will not work if run through a KO that has been removed. You might consider running a couple of spare 1/2" or 3/4" flexible metal conduits from the panel to a junction box in the attic.

IMO, your lighting installation does not meet the letter of the code, but this is one of those areas where it is probably not a big deal. By access, I mean remove the cover on the fluorescent fixture and have a hole in the fixture big enough to actually access the connections in the junction box. Had the fixture actually been attached to the box, there would have been no code violation.

toadf16

02:12PM | 06/05/07
Member Since: 06/03/07
3 lifetime posts
You mentioned putting the clamp side of NM cable clamps inside the box. Is this considered taboo by electricians? It would be the easier solution in my case.

Also, is there anything wrong with running more than one 12-2 through the same clamp and knockout in the new subpanel?

On the florescent lights, are you saying that it is probably acceptable to make all the connections inside the fixture itself? I have two NM cables coming into each fixture, save the last one on the run. Would you use pigtails still or just put a wire nut on the NM cables with the wire from the ballast on the light?

Should the sheathing on the NM cable extend into the light or just into the box like it is now?

Finally, must you use cable clamps on the knockout in the light?

Thanks again for your help.

Nate

Tom O

01:51PM | 06/06/07
Member Since: 09/17/02
487 lifetime posts
It doesn't matter if a "backwards installed" connector is considered taboo by electricians or not. Unless the connector comes with instructions that clearly indicate that it must be installed clamp side out, then it is permissible to install it clamp side in. Believe me, there are times when this is the only solution short of doing some serious demolition.

Unless the carton or package that the cable connector comes in is marked to indicate more than one cable per connector, then you can only put in one cable. Two brands that I know of that allow more than one cable would be NEER and Arlington.

I wouldn't lose any sleep over this fluorescent installation. You can usually run the cables directly into the fixture without using a box.Using pigtails if the cables come directly into the fixture is just adding a level of complexity that is not needed. When you connect the wires to the ballast, just give them a tug to see that they're not loose. I usually let the small ballast wire stick out past the big wires by 1/16th to 1/8" before inserting into the wirenut.

Sheathing should extend to the inside end of the connector.

Yes, you must use a cable connector when running the cable into a fixture.

Since you've already installed boxes and the lights, I'd just let them be.

Tom
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