Stab-Lok Main, HOM Sub Panel...


Old 10-29-05, 10:02 PM
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Angry Stab-Lok Main, HOM Sub Panel...

Hopefully, I never run into the clown that inspected my house. Just finished digging down around my septic tank for a new pump and pipe repairs. Finally took care of the mouse problem. The leaking roof is still on the agenda, among some other things I have to take care of.

Anyway, built a shed about 25 feet away from house last year. I ran and buried the wire during ground work. Before running it to the main figured I'd pick up a sub panel for my garage and do it all at once. The sub panel is 100 amp and has HOM & C circuit breaters. It was a main panel that I'll have to get a grounding bar for. My garage is attached but apparently was added on 2 years later, after the house. Some idiot fed the garage through the outside flood lights' circuit. My 110 5hp compressor or 110 mig, depending on the temperture of the garage will trip the circuit. Presently running in the garage is a freezer and a spare "beverage" fridge. It has (4) 4' flourescent shop lights and (2) up in the attic I built above. Table saw or grinders can also trip the circuit. Eventually plan on blowing the garage back another 12-16 feet. The garage now is 24x24. Will also need to heat it as well. Planning on temporarily putting up another shed behind the garage to house a 3 phase 80 gallon, 5 hp 2 stage IR compressor along with it's 7.5 hp rotary phase converter. Power will have to come from the sub panel as well. I went down to the municipal building for a permit for the sub panel. Apparently I only need one for my additional shed, which is much more important to them. The garage's lighting and recepticles are wired correctly, just the feed is the problem.

Now I got around to running the shed circuit up to the main. I looked up what kind of breakers I have and researched. I have a FPE 200a stab-lok main. Apparently I'm probably better to replace this ASAP rather than wait and hope nothing bad happens. Hopefully, I explained the situation well enough. Sorry for the book...Questions:

1) What size wire is required to feed the 100 amp sub panel, approximately 75 feet, at 100 amps?

2) Should I pick up a 200 amp main panel with HOM circuits breakers to be the same as the 100 amp sub panel? Maybe there is something better?

3) I've done wiring before but not comfortable with playing around live wires. I know I could label the individual circuits, remove and swap in the new box. However, would rather be able to cut off the feed to the house. Is this best left up to the electric company or would I need an electrician? If the meter box didn't have a tamper-proof seal on it, I would've looked in there today.

4) When selecting breakers, does the 125% rule always apply, even for compressors and welders or is it larger? I realize the ampacity of the wire will also have to be correct for the breaker.
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Old 10-30-05, 10:32 AM
Join Date: Sep 2000
Location: United States
Posts: 18,497
(1) If by 100-amp subpanel, you mean a panel fed by wires connected to a 100-amp breaker in the main panel, then the NEC says you need #2 copper in a cable assembly or #3 copper individual conductors. Some inspectors allow #4 copper or #2 aluminum, so you can check locally to see if this applies in your area and to your specific application.

(2) Are you talking about what should replace your main panel? If so, a 200-amp Homeline panel is fine.

(3) Replacing a main panel is not normally considered a DIY job. In most areas, power can only be cut off by the power company.

(4) The 125% rule does not always apply. Except in the smaller sizes, breaker sizing isn't goverened by a simple forumla. There are special rules for cooking appliances. There are special rules for welders. There are special rules for air conditioners. There are special rules for motor-driven appliances, and these rules differ depending on the type of motor. Life is simple for 15-amp and 20-amp circuits, reasonably simple for 30-amp circuits, but not simple above that.
Old 10-30-05, 12:10 PM
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Thank you for taking the time to answer my questions. Just a couple more to your responses.

1) Yes that is correct. I would rather have it it a cable assembly. It was previously suggested to me to use 4/0 and after calling a local electric supplier was 4/0 aluminum was the only thing available. Then researching again, 4/0 seemed like overkill and I rather stay away from aluminum, running through my crawlspace. What would be the exact #2 cable assembly terminology to ask for?

2) Presently my FPE 200 amp main has 22 circuits, using all thin or 1/2 breakers on a 24 slot panel. (8) 20a/2p, (1) 25a/2p, (1) 30a/2p, (6) 15a/1p, (5) 20a/1p and (1) 40a/2p. I'll have to add (1) 100a/2p to feed sub, from new box. The FPE main measures roughly 26"x15 1/2", recessed into a bedroom wall, covered by a cabinet door. Guess I will have to find a replacemnt main within the same size dimensions. If I go with a Homeline type main, are thin or 1/2 breakers available for them? Moreover, which manufacturer or type would that be?

3) I guess I'll be calling PP&L this week.

4) I asked mainly in regards to the 100a subpanel. More concerned with the phase converter and compressor hookup, than the welder. The rotary phase converter motor is 7.5 hp, 17.6 amps. The compressor is 5 hp, 15.2 amps. Anyone have a suggestion for which breaker to use?

Thanks again.
Old 10-30-05, 01:03 PM
Join Date: Sep 2000
Location: United States
Posts: 18,497
(1) More than one cable type will do. Look for 2-2-2-x (where x is probably 8) cable with copper wires. The cable must be rated for where you will install it (e.g., must be underground rated if to be installed underground). I'll guess that some of our other posters will have specific recommendations.

(2) I don't see why you need the same dimensions. This should not be a consideration. Openings can be made larger or smaller, and you'll probably have to rip off some of the drywall anyway to get proper access to do the work.

(3) If you have an electrician do the work, then let the electrician contact the power company. If you plan to do the work yourself, then get a permit and be prepared for an extended period without power. It would take an electrician all day to do this job. It may take you all week (or longer).

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