ELECTRICIANS: Is this safe/NEC/legal?

[Johnny_A_58]

Hi all, My Daughter just bought a house that was a mobile home, double wide, that was put on a foundation. Outside there is a service entrance panel with a 200A main breaker. That feeds into the basement to an empty box where it is bolted to an SE cable that runs the width of the house to the rear and up into the kitchen. There she has a 200A main panel with all the branch circuits.

I want to finish the basement for her. Assuming there is plenty of juice (there are 7 spares in the panel upstairs), here is what I would like to do if it is legal, safe and compliant with NEC (in Maryland),

Shut off the Main 200A outside Undo the bolted "feed thru" in the basement Rebolt it along with another set of 4ga/4 wires and put another panel there to feed the basement.

I know I could just use a subpanel in the basement and feed it from the kitchen, but if TWO main panels in parallel is legal, it would save me a lot of wire ($$). If I can do this, I would use a panel with say a 70A main breaker in it in the basement and not just a subpanel with main lugs.

Your thoughts? Thanks.

[John Grabowski]

*I'm not sure if I am understanding the entire scope of what you want to do. I'm thinking that you want to tap off the 200 amp line from the junction box in the basement with #4 wires. I haven't read the rules for taps in the current book yet, but I think that would be acceptable. You would have to bring those #4 wires directly into a 70 amp breaker and they would need to be close to the junction box. Also the junction box would need to be big enough for all of the wires. There are insulated taps that pierce through the insulation of conductors. You would not need to take apart the existing splices and then put them back together and retape them.

There is such a thing as feed through circuit breaker panels in which you could bring the existing wires into the top of the panel and exit the line to the kitchen from the side or bottom. They are more expensive than a regular panel and I don't recall if they are available in single phase.

When you get the electrical permit from the town for the remodeling ask the electrical inspector if it is okay. He will have the final word.

[clare]

They exist, but you'd never catch me using them. Junk. Fire waiting to happen.

[RBM]

Do you know of documented cases where fire occurred because of them, or do you just not like them?

[RBM]

What you propose sounds OK, although the devil's in the detail. There are very specific tap rules,but if you have a panel with a main breaker outside, and not just a service disconnect, you could run the feeder from there, if it's closer than the sub panel in the kitchen.

[John Grabowski]

*Clare that's the first time I have ever heard anyone say that they were a fire hazard. Do you have any supporting information on this. They are UL listed.

[clare]

For years CSA (Canadian Standards Association) would not allow them for safety reasons. Not sure if that has changed in Canada yet. A "positive mechanical connection" is required. That means bolted. I have not seen an IDC (Insulation displacement connector) that can be depended on - scotchlock connectors are time delayed faults anywhere they are used. IDC ribbon connectors on computer cables were a pain too, and they were low current (generally signal level) I refuse to install computer power supplies equipped with IDC drive power cable connectors because I've seen too many fail.

[clare]

Any information on how they are constructed/work? CSA did not approve the ones I've seen in the past. CSA tends to be more fussy than UL.

[John Grabowski]

*I've used these: You can connect them on hot wires without using any insulated tools.

[gfretwell]

CSA listed too.

Since he has simple access to the disconnect I would save some money and use the feed through lugs tho.

[Tom Horne]

A main breaker.

cable that runs

a 200A main panel

(there are 7 spares

afe and compliant with

n the basement

Since your main breaker for the new panel is seventy amperes and the feeder Over Current Protective Device (OCPD) is less then three times that, the twenty five foot tap rule would apply. You could purchase NSI/Polaris three port insulated splices; for instance; in the correct gauge range, break the splices at the existing junction box, and tap in your new seventy ampere feeder there. You can see the NSI/Polaris insulated splices here Remember though that you are allowed no more then twenty five wire feet to the terminals of the panel supplied by the tap. Choose your new panels location accordingly.

-- Tom Horne

[Tom Horne]

Which they are you talking about here? If your talking about the insulating displacing connectors that are used to do hot taps on larger energized conductors you must have worked with a different type then I have. I don't recall the brand off the top of my head but they were quite substantial. They were applied with wrenches and since I had not seen them previous to the job I had to use them on I checked them with a non contact thermometer attachment and my Fluke 87 III meter and found no heating greater then the joined conductors even with all of the heavier loads turned up so as to draw current. That doesn't mean I think they're the correct material for this job but I found nothing wrong with them.

-- Tom Horne

[Tom Horne]

If he uses the feed through lugs he would have to buy a two hundred ampere panel. That is an expensive option when your just finishing a basement.

-- Tom Horne

[The Daring Dufas]

I've used many of those Ilsco connectors in different sizes. It's one of those things that makes you want to hug the guy who invented them. *snicker*

TDD

[clare]

On Sun, 17 May 2009 09:09:44 -0700 (PDT), Tom Horne wrote:

>

[The Daring Dufas]

I'm not sure which connectors you're referring to but if you can snap off the bolts on the Ilsco connectors without using a long breaker bar, I would not want to meet you in a dark alley and have you mad at me. I've been using the Ilsco connectors for many years and have yet to have a problem with them indoors or out. I have used the Polaris type connectors too and they do a very good job. The connectors are designed for different situations and that's the way I use them.

TDD

[clare]

Correct - they are designed to be used where the "standard" connector is impractical. Still "second best" It's been quite a while since I saw an IDC tap - but back then I wouldn't touch them. Can't recall the manufacturer - but they used a torque-to-fail bolt like used on many automotive steering column/ignition switch setups. When you reached the right torque they snapped off - you could neither under torque or over torque them (theoretically) if you cranked them 'till the bolt sheared off.. However, if the joint "gave" you ended up with a loose connection down the line that could NOT be tightened - and removal from a live circuit was problematic, at best. All IDC connectors tend to be point or line contact devices by their very nature - which puts unneeded and undesired stress on the conductors, as well as limiting contact area.

Like I said - won't catch me using them, but it's a free world (within the confines of device approval) Pure aluminum wiring with standard wiring devices was once UL (and even CSA) approved too.. Even back-stab devices were once approved for AL wiring IIRC - and still are for copper. Doesn't make them right, or even safe, long-term.

[The Daring Dufas]

I love those Polaris type connectors for making connections inside troughs or panels where I have to splice wires. The labor and time saving over using split bolts more than pays for any price difference. I like them for new wiring like a new service entrance I installed for a building. It was a

400 amp 3 phase service and I used the connectors like those made by Polaris in the wiring trough under the breaker panels. I made sure I had extra ports on the connectors so future panels/disconnects could easily be added later. That's some- thing that would be a real chore with split bolts because the feed was direct to the transformer using a CT meter. At the time, the power company had no feed through 400 amp meters. When I come across a hot trough that can't be turned off, I'll use the Ilsco connectors if there is room. It's easy to tap a 750 mcm cable with them and I've never had one overheat or burn out.

TDD

[John Grabowski]

*You reminded of working with my father many years ago. When he did a tap on a basement underground service in Newark or Jersey City it was hot and with a load. He had rubber sheets and cardboard covering everything. Sometimes he wore gloves working with the wrenches and pliers to loosen and tighten the split bolts. I can fully appreciate the Ilsco's.