2. tech-talk
  3. 1236832030

Dedicated Lines - Sub panel or no?

Hi folks,

In a few months time I will be moving to a new home, where a spare bedroom and an understanding wife will enable me to enjoy the luxury of a dedicated listening room.

The first thing that comes to mind is installing 4 dedicated 20A lines. The breaker panel is on the ground floor, the room is on the 3rd.

I'm wondering which is better:

-to run all four lines from the breaker box all the way to the wall outlets,

-or install a sub-panel (is that the right term?) in the room, and use a single, very heavy guage line from the breaker box to the subpanel, then run 4 short lengths of 10 or 12 gauge from the subpanel to the outlets.

Thanks in advance for your advice

Kind Regards
Mick
128x128mickey_sg
hevac1
812 posts
 
I was using a 208 to 120 center tap stepdown transformer. 60Vac to ground both legs for balanced power.
I call the manufacturer and they said just to charge the coils is 4-5 amps on a 5 KVA trans.
ngjockey
1,042 posts
 
Hevac1,

Similar to mine, except I have a 5KVA 480/240-240/120. Wired 240V to 480V input and X1, X4 is +/- 60V with X2/X3 connected ("optionally" to neutral).

Just tested with analog clamp-on and I got 3.5A (average)per 240V leg and 7.5A on the outlets (93%). Unloaded, it was 1.5A on the 240V side, which was higher than I expected. Analog meter is not precise.

Wiring 120V to the 240V inputs proved inconsistent. We are going beyond the design and rating but it seems to help to stay as close as possible. I'm also using a GFCI on the balanced outlet, for safety.
ngjockey
1,042 posts
 
For more fun, I got lower amp draw, compared to unloaded, on the primary side when I had just a little secondary draw.
hevac1
812 posts
 
I am trying to find A transformer I can switch on and off. I am in the trade but it is taking a while to locate. A UPS could work but the last one I tried did not sound good.
I too had GFI outlets. Mine will be in the basement about 20' away.
ngjockey
1,042 posts
 
Transformers are like motors in that they can take 3 times the current at start-up. Maybe oversize the breaker and use a 3 phase starter with overloads. I've been installing Telemanique's recently because of the price and simplicity.

BTW, found the term for draw under no load is called "exciting current".
More to discover