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Old 02-08-2010, 01:03 PM   #16
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If they were the same price, then I'd go with a breaker panel. MLO will be fine - not worth the extra money for the slight convenience increase.
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Old 02-08-2010, 01:14 PM   #17
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I find I can buy MB panels cheaper than MLO a lot of times.
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Old 02-08-2010, 03:26 PM   #18
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Quote:
Originally Posted by secutanudu View Post
I think the 6-3 nm-b was less than $1.50 a foot when I was at lowe's yesterday.

The 50-amp breakers are $12 or so.

Do they make small (10-space or so) main breaker panels? It seems like main breaker panels are all very large (20+ spaces) so they are expensive. I only need about 8-10 spaces at most. This is why I was going to go witha main lug panel.
I used a panel from Lowes that is sized to replace old fuse panels. It's 100 amp with about 12 spaces but is smaller than typical panels. It was around $50.00 if I recall correctly. I think it was a CH brand. Worked great for me although I used it as a subpanel and not a fuse box replacement. It has the two buss bars, one for ground and the other netural and came with a 100 main breaker installed and secured.
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Old 02-08-2010, 03:46 PM   #19
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One thing I haven't seen mentioned in this thread is the need to keep the ground buss and the neutral buss electrically isolated in the subpanel. There should be a screw or strap in the panel that must be removed.
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Old 02-08-2010, 03:54 PM   #20
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Quote:
Originally Posted by cgoll View Post
One thing I haven't seen mentioned in this thread is the need to keep the ground buss and the neutral buss electrically isolated in the subpanel. There should be a screw or strap in the panel that must be removed.
Will do - if there is that bonding strap or screw I will take it out for the subpanel.
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Old 02-08-2010, 03:58 PM   #21
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Then double check for lack of continuity _before_ you hook up the wires in the main panel.

(Guess who had to disconnect the ground and neutral in the main for this test when he did his subpanel...)
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Old 02-08-2010, 04:01 PM   #22
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Good idea. I'll double check before hooking any wires to the main panel. Actually, I can check that before even putting the new panel on the wall.
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Old 02-08-2010, 07:15 PM   #23
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i would go with a main lug panel. you will probably get one set up for the neutrals and grounds to be seperated.
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Old 02-08-2010, 09:50 PM   #24
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Thanks. I'll probably just go with what's cheapest. I'll test for continuity (well, lack thereof) between the ground and neutral bars regardless before doing anything.

Thanks for the help, this should be a pretty simple project.
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Old 02-09-2010, 08:22 AM   #25
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In another thread about a subpanel....this question was asked and answered:

Quote:
Originally Posted by Magnettica View Post
-How can I tell that my main panel can handle this sub-panel?

By doing a load calc according to article 220.
What does this mean? Why would a main panel not be able to "handle" a subpanel? Do they simply want to know if they have enough "headroom" on their main breaker (100 amps, 200 amps, whatever) to be able to add the subpanel, and more importantly the devices being fed by the subpanel?

Or is there something else I am missing? Thanks.
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Old 02-09-2010, 08:50 AM   #26
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Basically it is a whole house electric calc
If you are adding additional loads there ia chance that you could start tripping the main breaker

Say you have a 100a panel, adding a 60a sub
Electric water heater, stove, dryer, some electric heat
At times your electric load may peak at say 70-80a (christmas lots of lights like me for a display)

Now you add a 50a hot tub...and the main breaker now kicks off when alll these loads kick on at the same time

I have a 200a panel, hot tub, electric WH, stove, dryer & my bill is ~$200 to $300 Max
My Load calc with all of this comes to around 140a
If your current electric bill is low & you do not have many heavy electric loads then unlikely you will trip the Main

I use the attached spreadsheet for my load calc



Attached Files
File Type: zip Electrical_Load_Calculator blank97.zip (7.1 KB, 62 views)
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Old 02-09-2010, 08:53 AM   #27
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Thanks Dave. Very informative and clear, like always.

Is there any way, either with a multimeter or clamp meter (I have a fluke t5-600) to get a current reading at the main breaker?

To get a rough estimate of current usage, could I turn everything on, then test? How do I test current on a 240v circuit? Put one lead on one hot, the other on the neutral? Then do the same with the other hot, then add the numbers together?
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Old 02-09-2010, 09:11 AM   #28
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There are clamp on meters, I do not have one
I'm guessing a little, but turning everything on & then testing each of the hot leads would give you a total

My electric bill back in '06 with ~120a if Chrismmas lights, electric dryer/stove/HW plus all the normal stuff I used 3642 kwh for the month

My 142a Load calc is if everything was on at the same time
Stove all 4 burners & oven, WH, dryer, heat, lights etc
Very rare you would have that happen

But of he has a 100a Main & lots of heavy electic items - AC/heat, WH stove then doing a Laod calc will tell you how much "free" power is available
If your Load Calc goes over the 100a then by Code you are supposed to upgrade
I'm not sure how often people do a load calc before adding a sub
Usually I hear...."I'll see if the additional loads trip the Main...then decide"

My last house I had the electric stove converted over to gas to free up enough power for a hot tub & AC
My HW, dryer & heat at that house were already gas
I had a very low elecrtic bill



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Old 02-10-2010, 09:46 AM   #29
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I talked to my brother, and it turns out the his current panel is in the opposite corner of the house from where the subpanel will go, and the whole run is through finished areas with drywall on the walls and ceilings.

I was thinking about using some sort of raceway or conduit and running it inside the room. According to this Raceway Fill Calculator, I need 3/4" sch 40 conduit to hold four 6AWG THHN wires (does the ground count? If not, I only will count 3).

A few questions...

1. Can I paint safely PVC conduit?
2. Is there a more decorative raceway I can use instead of PVC conduit?
3. Is THHN the appropriate wire to use in conduit to feed a subpanel from a basement to an attached garage?
4. If I use conduit with individual wires instead of 6/3 romex, can I safely use the full capacity of a 60amp breaker instead of the normal 55 amp limit?

Thanks.
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Old 02-10-2010, 10:31 AM   #30
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The ground does count for fill
I tend to upsize the conduit of there will be multiple bends
Max bends allowed 360 degrees between pull points
There may be some people who say not to paint conduit
I've seen it painted - no real problem

You could box the conduit in with wood/trim
Us THHN in conduit unless it goes underground at any point - then THWN
Yes with THHN/THWN you can use the full 60a



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