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magicfingers · Dec 24, 2008, 08:14 AM

I am installing a secondary subpanel in my basement/woodworking shop. The secondary break is 100 amp. There is no need for 240 volts and my equipment does not require it. I plan on only using one machine at a time but have several machines. The only item that will be running when a pwer tool is running is lights and my wood furnace which uses a single 110 outlet to operate it's two blowers. My question is concerningthe wire size needed to run from my main sup panel upstairs to the secondary panel. The wire distance would be 40-50 feet. Also would a 30 amp breaker be sufficient to hook onto in my main panel? Double or single pole?

stanfortyman · Dec 24, 2008, 09:10 AM

Do not run a 120v sub-panel. There is absolutely no reason to.

Even for just this small shop I would still run a 40 or 60A sub-panel. Again, there is no reason not to, especially for only a 40-50 foot run.

Run 8/3NM or 6/3NM from the main to the sub and install either a 2-pole 40 or 2-pole 60 amp feeder breaker in the main. You can use a main-lug panel for the sub, there is no need for a main breaker when the sub is within the same structure as the main panel.
Also, the grounds and neutral MUST be kept separate in the sub and you will likely need an add-on ground bar for the sub-panel.

Are you clear on the codes and practices involved in doing this job?

magicfingers · Dec 24, 2008, 10:31 AM

I already have a 100 amp subpanel that was given to me to use. Bit overkill I guess but it was free. Also, my father gave me some wire that he had leftover. It's has three wires. I believe it says 1 core is 6 gauge and two cores are 8 gauge or else 1 core is 8 gauge and two cores are 6 gauge. Would this wire suffice? When you say keep the grounds and neutral separate do you main all the neutrals on one lug bar and all the grounds and the other lug bar?

stanfortyman · Dec 24, 2008, 10:35 AM

The panel will be rated at 100 amps. Most are rated 100 or 125. This does not mean you have to feed it with 100A.

By cores do you mean conductors? I assume so. That will be fine as long as it has three conductors PLUS a ground.

Read what it says on the wire and post the info. Is it aluminum or copper?

magicfingers · Dec 24, 2008, 05:15 PM

The wire says : Capwire 2 Cor 6 AWG 1 Cor 8 AWG Type SE Cable style U 600 volts UL.

stanfortyman · Dec 24, 2008, 06:56 PM

Sorry, you CANNOT use this cable for a sub-panel.

Get you some 8/3 or 6/3 NM cable. :cool:

tkrussell · Dec 25, 2008, 05:25 AM

Sorry but just to clarify:

Originally Posted by stanfortyman

Sorry, you CANNOT use this cable for a sub-panel.

Get you some 8/3 or 6/3 NM cable. :cool:

Stan means 8/3 or 6/3 PLUS WITH GROUND, so the cable will have a total of 4 wires.

Many times, electricians know the ground is understood, but forget to mention it, and can be confusing to DIY'ers.

Magic, you use the word "core". Where are you located? This is a European term for wire. Maybe Canada?

magicfingers · Dec 25, 2008, 09:51 AM

Thanks for the answers guys. I'm located in Kentucky. The wire is some that was given to my dad years ago in a big spool. He had used some in the past and what he gave me was a piece that he had left. The cable itself said Cor on it so that's why I was saying Cor. Any idea what and 8/3 or 6/3 with ground costs now? It just bopught a 250' roll of 12/2 indoor at my local Lowe's for $46.00.

KISS · Dec 25, 2008, 11:49 AM

There is some odd stuff to worry about. There is usually a bonding screw (usually green) that connects ground with the neutral. It's removed for 4-wire sub panels.

A ground bar kit normally has to be purchased to use some panels as a sub-panels.

The panels that are typically used as "sub-panels" are called "main lug" panels. These don't have main breakers.

You can use panels with a main breaker panel even if the breaker is larger than the feed, (Say 200 A) even if they are fed with a 60 A source. This breaker can then be used as a disconnect.

Not applicable in your case are additional requirements for detached structures.

magicfingers · Dec 25, 2008, 05:54 PM

My sub panel has a 100 amp main breaker. There are two netrual lugs (one on the outside of each row of breakers) and 1 ground lug that is at the top right corner of the panel. I don't see any screws connecting the ground lug to the neutral lug. There is just a metal piece that connects the two neutral lugs together. With my 6 gauge wire I should connect the two hot wires to my 100 amp breaker, my neutral wire to the neutral lug, and the ground wire to the ground lug? I don't have to install an additional ground rod and wire do I?

KISS · Dec 25, 2008, 06:22 PM

Terminology issues:

Ground bar Kit such as this one: Square D PK7GTA Ground Bar Kit

This picture is of a main lug panel (not what you have)
http://www2.sea.siemens.com/NR/rdonl...L1200CUmed.JPG

Note the three sets. When using a panel with a main breaker the ground bar kit should be purchased for the panel. It must use machine screws.

There is USUALLY a green screw that when removed disconnects the neutral from the case.

Post a pic using "Go advanced" and maybe we can spot what you have to do. Alternatively post a make/model of the box.

To re-iterate:
There should be no connection between the neutral and the case and USUALLY a ground bar kit is required.

magicfingers · Jan 4, 2009, 01:59 PM

The make and model of the secondary sub panel is a GE PowerMark Gold Load Center TM12FC. It already has a ground bus bar installed. What do you mean by unbonding the neutral? It has a metal strap that connects the two neutral bus bars together. But the ground bus is not attached to these.