Advice converting Tripp-lite IS500 to tech isolator

[_Steve]

Hi!

I wanted to post this firstly to be sure im doing the right thing, but also as a reference thread for others as it's such a big safety issue and i couldn't find any clear written instructions - just a couple of youtube videos.

I've bought the Tripp-Lite IS500 for bench work on tube amps. I understand I have to disconnect the secondary ground from the earth ground on the primary/mains side to reduce the chance of shock and damage to test equipment. However when opening the box i found 4 protentional grounds to remove on the secondary side. Two of them are coming from the secondary side of the coil itself (one of which appears to branch from the neutral), and the other two going straight from the output receptacles to the grounding post. I wanted to check whether I disconnect all 4? Or just the 2 that connect to the outlet receptacles? There is of course a 5th wire from the input mains ground to the chassis post which im assuming I leave.

Here are some pics. I appreciate any help. ~ Steve

20200315_133207.jpg

20200315_133259.jpg

[Koolaide]

I am certainly no expert, but have researched the Isolation transformer a ton lately. In fact I have one coming next week.
It is my understanding there should be no ground reference on the secondary side. Be aware in the US and some other countries the neutral is connected to the ground at the mains panel. Therefore you would want to remove the neutral connection that connects to the ground secondary. Hope that makes since.
As I understand it you only want the case grounded from the primary side. The only connections you want on the secondary side are the two ends of the secondary winding to the receptacle for the Device Under Test.
Again I am no expert so YMMV
I recommend you look up Uncle Doug on youtube and find his Isolation transformer videos He has one where he converts a med grade IT for bench use. He clearly address this specifically.
Stay safe.

[_Steve]

I am certainly no expert, but have researched the Isolation transformer a ton lately. In fact I have one coming next week.
It is my understanding there should be no ground reference on the secondary side. Be aware in the US and some other countries the neutral is connected to the ground at the mains panel. Therefore you would want to remove the neutral connection that connects to the ground secondary. Hope that makes since.
As I understand it you only want the case grounded from the primary side. The only connections you want on the secondary side are the two ends of the secondary winding to the receptacle for the Device Under Test.
Again I am no expert so YMMV
I recommend you look up Uncle Doug on youtube and find his Isolation transformer videos He has one where he converts a med grade IT for bench use. He clearly address this specifically.
Stay safe.

Thanks this helped and confirmed my thoughts.

[Phil_S]

This might be worth reading.
https://antiqueradios.com/forums/viewto ... 8&t=286331

[_Steve]

This might be worth reading.
https://antiqueradios.com/forums/viewto ... 8&t=286331

Thanks for posting this. Its weird I googled like crazy before I made my post but didnt find that.

ANYWAY... as a follow-up and for anyone else googling about this transformer I would NOT recommend it for conversion to a bench isolator. I found that the output receptacles are chassis grounded within their plastic enclosures so no way to disconnect so there is continuity right through to earth ground for anything you plug in there.

The other thread above did also find this but they seem to say this is OK, but everything I have read so far seems to indicate the amp/project should be completely floating and have no earth ground path. PLEASE correct me if im wrong here (so that others wont read the wrong advice on such an important safety issue).

I managed to work around it by plugging in some 3-to-2 prong adapters that have no ground connection (see attached), but if you are looking for a bench isolator there may be better ones to buy.

20200416_141641.jpg

- Steve