[Housteau]

I will be expanding the size of my dedicated listening room in the near future and I am currently working the preliminary steps in doing that now.  So, I will have a nice opportunity to change how some of my electrical is run.  Right now I have a dedicated circuit from my breaker box going to the receptacles that power my system.  My system is multi-amped and so I have system receptacles on the wall between my speakers and the ones on the side for the source components.  I have the source components connected to a Monarchy isolation transformer now.  What I was thinking about was running my entire circuit from the breaker through an oversized industrial isolation transformer, something around 4 to 5KVA.  I would probably go 220 in with 110 out.  These units are not that expensive considering what we normally pay for our gear.  Is this a good idea, or am I way off base here?

[Big Red Machine]

I would vote yes on that.  I have a BPT Ultra 3.5 unit at 20 amps now and the entire system is connected to it.  I am very happy with what it does for the sound and noise.

[Housteau]

I was thinking something industrial such as this https://www.platt.com/platt-electric-supply/Dry-Type-Transformers-240-X-480-120-240/Acme/T-2-53014-S/product.aspx?zpid=1355

[drummermitchell]

I run two isolation transformers(Torus)which are 60a and 20a,both are 240v.
The transformers are huge and no compression of dynamics.
The protection is superb as I had four JL F-113's where two were plugged into the Torus and two were not.
As for the other two that were plugged into the wall,lets just say they are boat anchors.
We had a thunder storm here a few years back and the two plugged to the wall were dead and the two into the Torus were just fine.
All components plus projector which were into the Torus are all good also.
I have had these for 5-6 years and wouldn't be without them.
If they squashed the dynamics in the music,I'd look for something else as that is very important to me as is the superb protection.
I also just recently installed an EP-2050(whole house)as a first line of defence on their own dedicated 30a breakers,

[Housteau]

If they squashed the dynamics in the music,I'd look for something else as that is very important to me as is the superb protection.

I have not considered the protection side of things just yet.  It would be nice to combine both into an inline unit on my main power feed to the system.

[Housteau]

Most of the power isolation for audiophile systems come as units designed to be placed in the room with the audio components plugged into them.  I would like to take care of this before the power reaches the wall receptacles.  That is why I was considering industrial grade isolation transformers for use inline.  I realize that certain protections will not be there, but they wouldn't have been there with the straight raw feed either.  For the price one can get quite a good sized transformer for a fraction of one smaller specifically marketed to us.  Does anyone have any experience with them as opposed to ones specifically marketed to audiophiles, or have any reasons why using one would not improve upon the raw power being supplied, or believe they may actually cause harm in some way? 

[Speedskater]

Middle Atlantic has a most excellent paper on AC power:

"Integrating Electronic Equipment and Power into Rack Enclosures"
'Optimized Power Distribution and Grounding for Audio, Video and Electronic Systems'

See the isolation transformer section starting at page 19 and "The System Approach to Power Quality" on page 39.

http://www.middleatlantic.com/pdf/PowerPaper.pdf

*********************************************
Also note that 110v is a thing of the distant past. The  nominal 120/240V has been around for some time but now the nominal voltage is drifting towards 125/250V.

This can be problematic for some legacy or boutique equipment designed for lower line voltages.

[One and a half]

The installation of the transformer at the power box is a great idea. For reasons stated, you have the freedom to specify which transformer you can buy and it will reliably work as well as the ones designed in room. If you can, order a transformer with a shield between the primary and secondary windings (standard spec with mining equipment), even better if all windings have a shield, but you have to be careful, since this restricts cooling and can lead to an oversize transformer.
A nice touch is a temperature sensor in the windings to keep an eye on heating and incorporate suitable protection.

A few tips for the installer:

- Use a GFCI on the output as well as a fuse/breaker
- Since the transformer is located where the other circuits are close by, you can get RF breakthrough when say a switch turns on a light or the oven switches on/off. To avoid this, run a screened cable from the power feed to the isolation transformer. Alternatively use an EMC filter mounted close to the input side of the transformer. Keep the shield pigtails short, there are many guidelines on how to do this effectively.
- Size the upstream breaker for the transformer to allow for inrush (10x FLC for 10ms should work).

[Housteau]

That is an excellent paper on AC.  Thank you.

And very good tips for the installation.

I will have to look and see exactly how I will do this.  I was planning to source the isolation transformer from a 220 breaker in my remote box to directly feed my system receptacles.

[Cheeseboy]

I would vote yes on that.  I have a BPT Ultra 3.5 unit at 20 amps now and the entire system is connected to it.  I am very happy with what it does for the sound and noise.

Hey Red after our discussion that is the way I was headed as well.   I have been very impressed with everyone I talk to about the BPT units.  The reveiws I read by Sarjan were enlightening.  I was a heartbeat away from buying one.  My plan now is to install the Isolation Transformer at the electrical box and enjoy the Uber Buss from PI Audio in the audio room.   I think that will give me the best foot forward in Isolation and Filtration.   I don't think I could have found a better one box solution than the BPT 3.5.   Dave at PI is advocating whole house surge protection as an add on.   

My question to the team here would be does the Isolation transformer go before the whole house surge protection or after it?

[Russtafarian]

Don't forget Equitech.  FYI, Plitron provides the transformers for both Torus and Equitech.

[One and a half]

Hey Red after our discussion that is the way I was headed as well.   I have been very impressed with everyone I talk to about the BPT units.  The reveiws I read by Sarjan were enlightening.  I was a heartbeat away from buying one.  My plan now is to install the Isolation Transformer at the electrical box and enjoy the Uber Buss from PI Audio in the audio room.   I think that will give me the best foot forward in Isolation and Filtration.   I don't think I could have found a better one box solution than the BPT 3.5.   Dave at PI is advocating whole house surge protection as an add on.   

My question to the team here would be does the Isolation transformer go before the whole house surge protection or after it?

Recommend to still use the isolation transformer, as it provides some necessary inductance for the BPT and Equitech product.  Here's why.

The crud created by the line side of audio components is "cancelled" out quite a lot already by the symmetrical design of the secondary 60-0-60, however a small amount of imbalance still remains and this is reflected into the primary. This can manifest itself as a buzz in the BPT or Equitech. The isolation transformer provides dampening of these effects without any fancy electronics and is not caused by DC. For my application, I used a 2kVA isolation transformer with a 1kVA Equitech, and it removed the buzz instantly from the Equitech.

What a symmetrical power supply can do for your audio listening pleasure is something else again. Should have bought it years ago. It does it all, lower noise floor, especially for digital, better bass, and you get to hear those fine details that you thought were buried. They are all there. The other week, I moved the Mac Mini on to a standard outlet, cause I was in a hurry in an install. The music sounded awful, really rough and very digital and wondered why, thought back, oh it wasn't on the Equitech. Put it back and all is good!

[One and a half]

 

My question to the team here would be does the Isolation transformer go before the whole house surge protection or after it?

Very much after it. The transformer is not rated to supply full fault current to the whole house.

[Housteau]

This one looks interesting:  https://www.platt.com/platt-electric-supply/Dry-Type-Transformers-240-X-480-120-240/Sola-Hevi-Duty/HS5F5AS/product.aspx?zpid=272366

[jea48]

I will be expanding the size of my dedicated listening room in the near future and I am currently working the preliminary steps in doing that now.  So, I will have a nice opportunity to change how some of my electrical is run.  Right now I have a dedicated circuit from my breaker box going to the receptacles that power my system.  My system is multi-amped and so I have system receptacles on the wall between my speakers and the ones on the side for the source components.  I have the source components connected to a Monarchy isolation transformer now.  What I was thinking about was running my entire circuit from the breaker through an oversized industrial isolation transformer, something around 4 to 5KVA.  I would probably go 220 in with 110 out.  These units are not that expensive considering what we normally pay for our gear.  Is this a good idea, or am I way off base here?

Housteau,

I assume you live in the USA.

If you purchase a 5kva transformer and have a licensed electrician in your area install and wire the transformer he will be required to follow the AHJ, (Authority Having Jurisdiction), Code  in your area. In most cases AHJ meets and or exceeds NEC Code minimum standard requirements.

Yes the primary should be wired for 240V in and the secondary for straight 120V out.
Also it is a good idea to install the transformer in a room other than where your audio equipment resides.

How much power will a 5Kva transformer deliver at 120V under full load if the primary feeder is sized and fused properly?

5000Va / 120V = 41.67 amps.

You cannot connect your audio system's dedicated branch circuit wiring directly to the secondary of the transformer. That would not meet NEC Code. For one thing the branch circuit wiring would not be big enough.  Second, the maximum overcurrent device, breaker, that two NEMA 5-15R 120V 15 amp receptacles, (a Duplex is two), or a NEMA 5-20R   120V 20 amp receptacle is 20 amps.....

The electrician will be required to install a small electrical panel with a main single pole 40 or 50 amp breaker.
A single pole 20 amp breaker will be installed in the panel to feed your existing dedicated circuit providing the branch circuit wire is at least #12 awg.

As for the proper sizing of the wire feeding the primary winding of the transformer the data plate FLA  should be used.

5000Va / 240V = 20.8 amps.
20.8 x 125% = 26 amps. Minimum wire size is #10awg copper.

Breaker size?
A couple of options.
1) 125% of data plate primary winding FLA.  If FLA is 20.8 amps at 240V,  20.8 x 125% =26. NEC code roll up to a 30 amp 2 pole beaker.

2) Where secondary protection is provided.
Up to 250% of data plate FLA is allowed. You will not need to use this calculation.  125% should be more than enough to handle cold start up inrush current of the transformer with no more connected load that you will have.

The electrician will bond one lead of the secondary winding intentionally to the existing grounding electrode system of your home. This lead will become the Grounded Conductor, the neutral conductor.... The electrician will also bond the transformer enclosure as well as the electrical panel depending on where he decides to bond the neutral conductor and grounding electrode conductor together. He can do it at the transformer or he can do it at the new  electrical panel. But not at both. I would prefer at the new electrical panel. (I assume the transformer and new electrical panel will be next to each other.)

>>>>>>>>>
Now a few facts about a common dual winding transformer.
Take for example a single phase 5Kva transformer that is designed and wound to be connected to 240V or 480V and the secondary is designed for 240/120V or straight 120V out.

In your case you will be feeding the transformer with 240V. The 2 primary windings will be connected in parallel.

Secondary? This is where some guys, electricians, mess up. They will wire the transformer for 240/120V volt to feed the new electrical panel. The customer tells the electrician to install the breakers that will be feeding the audio equipment, that will be connected together by ICs, on only one Line, leg, of the panel.  In your case, at the present time, you only have one branch circuit.
What is wrong with this picture? Only one winding of the secondary is being used.
Only 2.5Kva, half, of the available power will be in play. Each winding is rated for 2.5Kva. 2500Va / 120V = 20.8 amps.
So in your case you want both windings, observing polarity, wired in parallel. The new panel will be single phase 120V only. Max available amps  41.67.

The above is only intended as a general outline of the wiring method used for a 5Kva power transformer. It is not meant as a complete wiring installation guide.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Now let’s talk about  a so called balanced power system using the same dual primary and dual secondary 5Kva transformer. Can it be wired for balance power? Yes. Did the manufacture design the transformer to be fed by half the data plate voltage rating? No…. But it will work but not as efficient as it would powered within the voltage tolerances of its design.

The 2 primary windings will be connected in series and connect to a 240V source. (Feeding the transformer with half its rated voltage.)
The 2 secondary windings will also be wired in series. The center point of the two windings will be intentionally connected to earth and becomes the neutral, The Grounded Conductor. (Per NEC Code earth will be the grounding electrode system of the main electrical service of your home.)  This connection is not used for power. We now have a 120/60V grounded AC power system.
Or more commonly called on audio sites a 60V 0V 60V grounded AC balanced power system.
120V Output per NEC CODE shall be GFCI protected. All 120V branch circuit breakers shall be  2 pole.  Also I have to mention it is a violation of NEC Code to install a 120/60V grounded power system in a residential dwelling unit in the USA.
NEC Article 647.3 General

The two secondary windings are in series with one another. Voltage out Line to Line will be 120V nominal. From either hot ungrounded conductor to the neutral conductor will be 60V nominal.


Want to guess what will be the total available output FLA of the name plate 5Kva rated transformer?

20.8 amps max…..
Half the power than if the transformer was wired with the two secondary windings in parallel for 120V out and the primary wired for the data plate rated voltage.

Remember the manufacture designed the transformer to deliver a max of 20.8 amps per secondary winding FLA at the rated data plate connected primary  voltage.
Putting the two 60V windings in series will yield a 120V output. But the available max FLA will be the same as if the transformer was 240V out.
5000Va / 240V = 20.8 amps…… 


http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
Scroll down to page 200. Worth while reading……
Jim

[Housteau]

Thank you for the time in putting all this together.  It is full of very important and useful information for me moving forward.

[coxhaus]

I have a 5Kva power isolation transformer used for separating my analog from my digital components.  It is fed with a 220 volt 20 amp breaker out of the main breaker box using 10 gage wire.  The isolation transformer feeds two 10 gage circuits straight to the wall plugs. Each 4 plex is isolated from each other so I only plug analog into one and digital into the other.  If you use a Fluke and test the positives from each side they net to zero not 220. I have an EE friend which designed this system and it seems to work well.  I think this is simpler than trying to use balanced power or creating circuit breakers for each of the legs after power isolation.

[Housteau]

My new room is nearly complete and I have my new isolation transformer.  I have a choice of primary taps.  My home is supplied with approximately 246 V.  If I use the 240 primary tap my secondary is around 123 V.  The tap for 252 V has an output of 117 V.  Which one is best to supply my audio circuit with?

[Speedskater]

Do you have modern equipment or legacy/boutique equipment? Over the decades, nominal US line voltage has been drifting upwards. 110V then 115V or 117V then 120V but now all new UL listed equipment is 125V.
But power transformers don't like overvoltage, so if you have old equipment use the lower voltage setting.

[Housteau]

Thank you.  I will set it for 117.  There are threads on different specialty forums here on the Circle about building my new room.  I will be posting photos when it is finished on one of them with links for the others.