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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
jea48
4,452 posts
 
But some suggest this cuts the power in half, some suggest it doesn’t. Here is an example I found of balanced wiring:
Wired balanced will cut the VA rating in half.....

Wire the transformer 120V in 120V out.

Parallel the two secondary windings together.

Warning: Observe the correct polarity. If polarity is not followed the two secondary windings will buck one another possibly burning up the windings.

Is there a data plate on the transformer showing wiring configurations?

Primary? One winding or two? Input voltage/s? Number tags on leads? Polarity marking?

Secondary? One winding or two? Secondary voltage/s? Number tags on leads?
Polarity marking?
xti16
1,525 posts
 
Wired balanced will cut the VA rating in half.....
NO IT WILL NOT. What you will see is 60V between ground and neutral and 60V between ground and hot. You will have 120v between neutral and hot. I have the 2.4KVA version
jea48
4,452 posts
 
NO IT WILL NOT.
Yes it will!

You must treat the output rating the same as if it was configured with the two windings in series.
herman
2,259 posts
 
First of all, if you are not sure how to do this I seriously suggest you enlist the help of someone locally who can help. It is possible to kill yourself or burn your house down if you screw up with electrical work.

To run it balanced you'll need to connect it as you stated but also jumper H2-H3 on the primary otherwise no current can flow. That puts the 2 primary windings in series and also the 2 secondaries so it is a 1:1 transformer.

The full VA rating at 120VAC assumes you are running the 2 primaries as well as the 2 secondaries in parallel so each winding carries half of the current.. Running balanced you will have them in series so VA rating is half since full current runs through each winding, not half of it.

.
jea48
4,452 posts
 
120V in 120V out will not yield all that much isolation. Better to wire the xfrm 240V in, single ended 120V out.

Series the primary windings, parallel the secondary windings.
One paralleled leg of the secondary must be connected to earth ground making the new derived ac power system a grounded ac power system.... it's a safety thing. The earth ground used must connect to the main grounding system of the main electrical service.

For this you would need to hire an electrician.....
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