Replies

1. 
   Alex_B | Mar 05, 1999 09:28pm | #10

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   Mike, Thanks for the clarification (my face is red). I should have refered to "legs" rather than "phases". The SE panel in my house does indeed have 1/2 high two pole breakers. A slot in the case positions the breaker so it draws current from each leg.

2. 
   Guest_ | Mar 05, 1999 09:28pm | #11

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   My breaker box is apparently full, and I need to wire my shop, a small shed behind the house.

   Will it be safe and wise to use tandem breakers to free up space in the box?

   Would it be possible to just power a sub panel in the shed, running from buses in the present box?

   If you're leery of advising me about this kind of work, please say so. I won't start something that's too risky. But I am methodical, and I'm willing to make the effort to do it right.

   JS

1. 
   Guest_ | Feb 17, 1999 01:36am | #1

   *Yes. No. I would put in 1/2 size breakers to free up enough space for a 2 pole to supply your shop subpanel.

1. 
   Guest_ | Feb 17, 1999 03:30am | #2

   *I too, would use half-width breakers to make enough room for a double-pole to a subpanel, unless you only need one or two circuits in the shop. Then I would use half-width breakers to create enough room for breakers for those one or two circuits and skip the sub panel, if your inspector allows. For some shop equipment, you need (and may want) a shut-off within line of sight of the equipment. Then go with the sub panel. And try to get the same brand of sub-panel as your original panel and you'll be able to reuse those full-width breakers in the shop sub panel. You say "apparently full". Either it's full or it's not. Take the sheet metal cover off (turning off the main breaker if you are nervous about it but realize that the two lugs where the feeder comes in are live even when the main breaker is off). If you've got empty lugs or terminals on the center bus, you've got more room for breakers. (Although the sheet metal cover may need to be trimmed). If not, you don't. Happy Wiring. -David

1. 
   Guest_ | Feb 27, 1999 09:07am | #3

   *There should be printed information on the paper label inside the panel cover which will tell you how many "poles" or breaker slots your panel is rated for. Sometimes you can physically put in too many half-sized breakers when the panel isn't rated for them all. The second thing to watch out for is that you should be careful not to change the phase relationship of any of the existing circuits unless you know exactly what you're doing. You could end up with an overloaded neutral if you tandem up a three-wire circuit improperly. Third, if you're shed is detached it should have it's own grounding rod system. Your question about taking directly off the main panel buss is kind of involved but if you're really interested we could do a few more posts. Lee

1. 
   Guest_ | Feb 28, 1999 01:14am | #4

   *Good point about phases...whenever we do that, we put a little colored "sticky dot" on each of the two breakers. Same color dot for the pair. A decal (same kind that goes on a 1.44MB floppy) with the same colored dot is then put on the inside of the panel cover explaining the setup. Not to tough to do, and it helps keep things squared down the road. Hopefully, anyway!Mongo

2. 
   Guest_ | Feb 28, 1999 06:48am | #5

   *Your concern should not be available space for breakers but rather your total amperage requirments and if your service and panel busses can handle the extra loading. Consult a professional electrician. This is one hobby that can kill you and others.

3. 
   Guest_ | Feb 28, 1999 06:57am | #6

   *Gregory,Their are a million ways to the graveand playing in a main panel sure is one of thequicker ones...I also think it's one of the easiest trades inbuilding a home.  The how to books are great, and there is aplethora of them to choose from.Two of my first tips....never work with two handsin the main panel...stand on dry wood and in dry shoes...bit a few times but never jolted,Jack : () )(

4. 
   Alex_B | Mar 02, 1999 12:39am | #7

   *Tandem or 1/2 inch breakers allow you to pull and break two circuits from one tab on a hot buss bar. Not all tabs will accept the tandem breakers. The tabs for tandems have litte cross tabs on them. A 40 space 40 circuit panel won't take tandems.Because all tabs are centered,when you move your circuits around, make sure the amps and phases remain the same. That is, if you take two 15 amp circuits loose on the right side, be sure they are from the RIGHT buss or vice versa. This is assuming your amp load was balanced in the first place.Also, when you install your breaker for the garage load (two pole full size)(120 volts from each buss) make sure the trip levers are connected so that a trip on either phase will break both phases.Consider running 4 wires to the garage to take care of grounding. If the inspector allows.Problems with inspectors usually start with bad attitudes and poor people skills. Find out how he wants it done and do it his way. Most inspectors want to be appreciated and valued. They practically glow when shown some respect.Finally, most things run on smoke. You know you're in trouble when the smoke escapes.

5. 
   Guest_ | Mar 02, 1999 08:37pm | #8

   *Most manufacturers' have proprietary methods for excluding half size breakers. The tabs you mention is only one method. Even if 2 brands of breaker are interchangable, the half size breakers of those same two brands will not necessarily be. To be safe, you must use half size breakers of the same brand as the panel. Some brands have half size 2 pole breakers, others don't. The maximum number of breakers permitted in a panel is 42, regardless of size. So a panel will be sized at 8/16, 12/24 etc. The first number is the full size breakers it will accept the second is the half size. To talk about 2 phases is misleading. There is only one phase in single phase service. There are 2 legs. Those together constitute one phase. The main lugs or main breaker in a panel connect to the right and left sides of the buss, but the buss is built so that the full size breakers down oneside of the panel alternate between legs. It is important not to change legs with circuits, unless you know what you are doing.

6. 
   Guest_ | Mar 04, 1999 12:12am | #9

   *Remember to use an isolated neutral buss on the sub panel. Do NOT tie it to the ground.