Wiring an Isolation Transformer


I found a pristine, never been used, Topaz (Square D Company) 91018-31 1.8 KVA Ultra Isolator Line Noise Suppressor for $40. Other markings include .0005pF, 50/60 Hz, 120/240, Indoor Type 1, Enclosure Class 1-80 Insulation. However, it has no receptacle or chord.

My first question to the forum, is how to wire it? Could I just take a short extension cord, cut in half, wire the male end to the output side and the female end to the input side? Should I use bare wire under the screw terminals, or should I crimp/solder on spades? What wires go on what screw terminals? Some suggest balanced is the way to go. But some suggest this cuts the power in half, some suggest it doesn’t. Here is an example I found of balanced wiring:

Input:
Neutral (white) to H1
Hot (black) to H4
Ground to chassis

Output:
Hot 1 (white) to X1
Hot 2 (black) to X4
X2/X3 center tap connected to chassis ground and outlet ground.

Is this all there is to it? I am a complete newb when it comes to electrical work. Is this something I can do myself, or should I hire an electrician? Any assistance would be greatly appreciated.
cpalcott

Showing 6 responses by cpalcott

I have one dedicated 20A line run to my audio system. My plan was just to run digital components (Apple TV, DIP, Pre/DAC, Video Switcher maybe a Tivo) off it. Run the power amp and tv straight to the wall. 220 is not an option right now. Any ideas about what gauge of wire I should use for the jumper cables and in/out cables. Also, is there a definitive asnwer out there about balanced halfing the VA rating? Also, would I use bare wire, or should I solder/crimp spages on the wires?
So does the following seem like a practical approach? Will this get me balanced isolation? Are their any safety concerns with this setup? Can I just use a good extension cord, cut in half, and wired in the manner described below?

Input:
Neutral (white) to H1
Hot (black) to H4
Ground to chassis
Jumper H2 to H3
Add appropriate inline Fuse/Holder

Output:
Hot 1 (white) to X1
Hot 2 (black) to X4
X2/X3 center tap connected to chassis ground and outlet ground.
I have a friend who is an electrician coming over tomorrow. He has some experience with wiring isolation transformers. But I need to be able to tell what I want. So, if I am understanding this correctly, some are suggesting wiring this as 240v in 240v out even though it will be on a 120v circuit to help keep it cool. Is this correct? Will this work? It seems consenus that if I have it wired balanced, it will half the kva rating. If I do that, will .9 kva be enough to run the digital part of my system (Apple TV, Monarchy DIP, Tube Audio Designs TADAC Tube Pre/DAC, AV Switcher, and perhaps a Tivo)?
Today I had the unit wired as described above. The electrician checked it with a multi-meter and got stable correct voltage. Just for giggles, I decided to hook up one of those cheap Home Depot plug-in testers to the unit, and it is showing an open ground. Is this a misread from the tester or is there something wrong with the wiring? Any help?
Ok, I heard fromn the electrician. I now undertstand the open ground reading was expected behavior. My only remaining question is, how many watts can I safely put on a 1.8 KVA iso transformer? I had it wired for balanced, so I am assuming that knocks the rating down to .9 KVA which would equal 900 va/watts, correct. Cut that in half to allow sufficient headroom would equal 450va/watts to work with. Is my math correct?
Thanks for the reply Ngjockey,

TADAC Tube Pre/DAC = 25W According to Paul at TAD)
Apple TV = 20W (according to Apple)
DIP (Original) = 10W (according to back panel)
Tivo HD = 40W (according to tivocommunity)
Video Switcher = (don't know but could it be much?)
TV = 240W (according to manual)
McCormack DNA-1 Deluxe = 400 (according to SmCAudio)
TOTAL = 735W (certainly pushing it depending on the draw of the switcher)

I don't have all this on the xfrmr right now. Just the PRe/DAC, Apple TV, DIP, Video Switcher and Tivo. In your opinion, what would be the most beneficial strategy for using the iso? I guess I just threw everything on there that I thought it could take. Anyway, it is buzzing but I can only hear it when I put my head right up to it. Can'thear it from listening position at all. Just barely warm after running it all night. I have to admit, I was skeptical about how much difference this would make. But it is significant. Not night and day, but very noticeable. The only way I can describe is that everything is just so much more right sounding. Whatever that means.