My last sub panel (pretty sure) - DIY Chatroom

**Scuba_Dave** · 11-02-2009, 09:55 PM

So I'm getting ready to setup my last sub panel
I had the main 200 panel replaced & kept it to use as a sub-panel
It's 200a & I'm going to feed it with 100a
Distance from Main panel to sub will be about 27' of wire
This is going in the addition - attached
Its going in the bottom landing of the staircase leading to the attic
Area meets all clearances required for a sub

Planning on #3 copper in conduit,2 hots & neutral.....#6 for ground OK?
Funny, HD has magic marker notation on their wire sale board that #4 is good for 100a....True?
I want the full load capability of the 100a panel, I know #4 is rated at 95a in the 90 degree column
Electrician ran #3 for my other 100a panel 4' from the Main panel
Grounds & Neutrals will be on seperate buss

This will be used to feed power to the addition: garage, great room & attic
There will be a 50a 240v stove - probably very rarely used - in bar area
Bar will have a mini-fridge plus 2 circuits same as a kitchen area
Then another circuit for a microwave
There may be a 30a 240v AC breaker
There will be (7) 20a circuits for Christmas lights & decorations
I may consolidate (6) other circuits to this panel for Christmas lights
---depends upon if I (ever) need room in the main panel

spark plug · 11-02-2009, 10:22 PM

Good Luck with your project. And we hope to see your display of Christmas decorations, part of which you showed in July. But in my book a #4 AWG wire is rated for 70Amps. Not a one more. #3 or #2 is what we use to feed 100 Amps.

kbsparky · 11-03-2009, 02:30 PM

#4 is only rated for 100 Amps when used as the main feeder for a dwelling, per 310-15(B)(6).

Since this is not the case, you will have to use a #3 as stipulated. A #8 ground would be sufficient for this setup.

Spark plug, the 70 Amp rating for #4 copper wire is listed in the 60 degree column. You are allowed to use the 75 degree column when using wire rated for that temperature, and when terminating at equipment listed for that rating.

spark plug · 11-03-2009, 10:50 PM

Quote:

Originally Posted by kbsparky

#4 is only rated for 100 Amps when used as the main feeder for a dwelling, per 310-15(B)(6).

Since this is not the case, you will have to use a #3 as stipulated. A #8 ground would be sufficient for this setup.

Spark plug, the 70 Amp rating for #4 copper wire is listed in the 60 degree column. You are allowed to use the 75 degree column when using wire rated for that temperature, and when terminating at equipment listed for that rating.

Thanx, KB. That's why I (think I did.) coined the phrase; "Eliminate confusion

(Ultimate symbol of confusion) through Education

!

**Scuba_Dave** · 11-03-2009, 11:55 PM

Thanks
I always hear different columns used
I tried to find the thread where someone explained the 90 is for SE
But I couldn't find it

I wonder how many people buy the wire HD advertises on the sign

I ran into another problem with some self destructing drain pipe
So the sub will be maybe next week

WaldenL · 11-05-2009, 02:43 PM

Quote:

Originally Posted by Scuba_Dave

I wonder how many people buy the wire HD advertises on the sign

Good news is that there's enough of a safety factor built in that they'd likely not cause any problems. Bad news is you shouldn't rely on the safety factor, most people buying @ HD probably won't have the work inspected so the inspector won't catch the mistake, and most people don't have access to sites like this. Too bad.

As for the sub, I think once you throw a stove in there, used infrequently or not, you've not created yourself a second kitchen. Make sure you're adhering to the SABC requirements for a kitchen including the dedicated circuit requirements.

**Scuba_Dave** · 11-05-2009, 04:49 PM

Quote:

Originally Posted by WaldenL

As for the sub, I think once you throw a stove in there, used infrequently or not, you've not created yourself a second kitchen. Make sure you're adhering to the SABC requirements for a kitchen including the dedicated circuit requirements.

huh ?

I think you mean I did create a 2nd kitchen...an even better one
Stove, sink, microwave, fridge & booze

It will be setup & wired just like a kitchen
It will actually have more then the 2 circuits required for counter tops - as will the current kitchen
Have to be able to have multiple blenders going, TV, PC, croc pots & who knows what else going out there

Wife was sort of against the old Stove going out there
But when I said it would be a full kitchen setup she could cook out there she sort of changed her mind
I know once it is built in a few years she will probably want the old stove (in the bar area) replaced with a new one

WaldenL · 11-05-2009, 04:52 PM

D'Oh!

Yes, I meant that you have created another kitchen.

**Scuba_Dave** · 11-13-2009, 08:18 PM

hmmmm....I was thinking of putting the panel in recessed
But the vent pipe of course is right behind the panel
And there are too many studs
So I was going to mount it to the studs
But there is balsam wool insulation in the wall too - encased - not loose
So...is plywood or a mounting board required...or a good idea w/the balsam wool insulation?

This will be in an unheated area that will border the kitchen
So I want to leave the insulation

**Scuba_Dave** · 11-17-2009, 08:02 PM

The LAST sub-panel is installed !!
I thought they gave me the wrong wire
I saw the wire rated as #2 THWN......But it is labeled as #3 AWG

That has me a little puzzled

I ran 4 circuits to the attic - these can all be used for Chirstmas roof decorations
I think that will be enough for the roof (better be)

I still have a little work to do in the Main panel before I button it up & hopefully won't have to open it again
Wires run, to be connected:
30a Steam heat for new 2nd floor steam shower to be connected
Master bedroom AC

Main panel is full, but I have 6 circuits I will move to the great room panel at some point
These are dedicated circuits for Christmas display w/hard wired timers

kbsparky · 11-18-2009, 02:30 AM

Quote:

...I saw the wire rated as #2 THWN......But it is labeled as #3 AWG
That has me a little puzzled...

THHN/THWN wire is rated for 90º dry locations, and 75º wet locations.

THWN-2 means that it is rated for 90º in wet locations and is a wire type insulation designator, not the size of the conductor.

Conductor size is marked in AWG (American Wire Gauge) as you noted.

**Scuba_Dave** · 11-18-2009, 08:52 AM

Thanks, I knew there was a rational explanation
Just gave me a jolt when I saw the #2 & thought I had the wrong wire
Had to get my glasses to take another look

spark plug · 11-18-2009, 02:27 PM

Quote:

Originally Posted by Scuba_Dave

The LAST sub-panel is installed !!
I thought they gave me the wrong wire
I saw the wire rated as #2 THWN......But it is labeled as #3 AWG

That has me a little puzzled

I ran 4 circuits to the attic - these can all be used for Chirstmas roof decorations
I think that will be enough for the roof (better be)

I still have a little work to do in the Main panel before I button it up & hopefully won't have to open it again
Wires run, to be connected:
30a Steam heat for new 2nd floor steam shower to be connected
Master bedroom AC

Main panel is full, but I have 6 circuits I will move to the great room panel at some point
These are dedicated circuits for Christmas display w/hard wired timers

Just referring to the first Paragraph. I had a similar issue with an Electrical Inspector. He thought the wire was undersized for the load. I pulled the wire to show what's stamped on the (run of) wire. That decided the issue. Good Luck.