Mains panel

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MIcAngelo

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Audio engineer
Hello Everyone I have a question. I am in a 6000 sq foot building for over 35 years. It used to be a factory. I have a 3 phase service coming into my building 120/120/208 + neutral . I think it's called a Delta Wye. As soon as the 4 wires enter the building, they go into an enclosed electrical box whereby they are each doubled so they can split off to 8 wires.

4 wires go straight up to a mains panel with 200 amp main breaker and the other 4 wires go to a large disconnect with fuses. IN this large disconnect the neutral meets the case of the disconnect metal shell and the water pipe ground. the output of that goes to a 100 amp sub panel ..

The main 200 amp breaker panel does not have the neutral bonded to its case , (just like my sub panel) is this ok? or should I connect the mains 200 amp breaker panel from the large disconnect where the other sub panel comes from?
 
I am closing this thread in accordance with forum rules. We are not allowed to assist a person who is not an electrician to perform their own electrical installation work.
 
Since this thread question is not a DIY installation (the poster confirmed this) and the OP is requesting information regarding their electrical contractor I'm reopening the thread.
 
infinity said:
Since this thread question is not a DIY installation (the poster confirmed this) and the OP is requesting information regarding their electrical contractor I'm reopening the thread.
Click to expand...
Thank You sir. Just seeking information ..not always easy to get a extremely well informed electrician. Actually I had my old electrician ( he died) do a deep earth ground in my building, whereby he drove 80 ground rods 100 feet into the earth in 8 locations around my building to achieve a resistance to earth of .5 ohm. Of course the water pipe ground is still connected. My building houses a world class recording studio and audiophile set-up. We know the electrical wiring configuration and power that feeds our high end electronics is critical for ultimate sound. Thank You for reopening this thread.Thank you.
 
I seriously doubt any of the efforts to reduce the earthing impedance made any real difference.

There needs to be a bond between neutral and earth at a single point. Often that bond is a screw that goes through the neutral bus in the main panel into the metal of the main panel enclosure. That is all that is required and all you need.
 
Low resistance connections to Planet Earth have nothing to do with day-to-day AC power quality.
Did the person that did the ground rods last name start with a 'K' ?
 
Well, to be honest, there was a huge Sonic improvement in our Mastering room when we added the deep earth grounding to the water pipe ground. But I have another question? my electrician measured current on the water pipe ground about 3.8 A. Using the AMEC 3731 tester . Why is there current on water pipe grounds usually ?
 
MIcAngelo said:
Well, to be honest, there was a huge Sonic improvement in our Mastering room when we added the deep earth grounding to the water pipe ground. But I have another question? my electrician measured current on the water pipe ground about 3.8 A. Using the AMEC 3731 tester . Why is there current on water pipe grounds usually ?
Click to expand...
And by the way, my water pipe ground has a very low impedance of 1.8 ohms and there is no plastic conduit between my building and the water mains in the street
 
MIcAngelo said:
my electrician measured current on the water pipe ground about 3.8 A. Using the AMEC 3731 tester . Why is there current on water pipe grounds usually ?
Click to expand...
The earth is a conductor and current divider.
Why not look into an article 647 system.
 
MIcAngelo said:
Why is there current on water pipe grounds usually ?
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Because Neutral currents will take all available paths to return to their source. Their source is the big power company transformer. An all metal water pipe system is often a low impedance path to that transformer.
 
MIcAngelo said:
Well, to be honest, there was a huge Sonic improvement in our Mastering room when we added the deep earth grounding to the water pipe ground. But I have another question? my electrician measured current on the water pipe ground about 3.8 A. Using the AMEC 3731 tester . Why is there current on water pipe grounds usually ?
Click to expand...
Usually because you are getting some current flow thru the earth between your neutral to earth ground and the neutral to earth ground at the utility transformer.

It could also be coming from a neighbor if you share utility transformer and water piping.
 
While a small amount of the Neutral current may pass thru Planet Earth on its way to the power company transformer, the metal water pipe system and the Neutral wire both will have much lower impedances.
 
MIcAngelo said:
my electrician measured current on the water pipe ground about 3.8 A. Using the AMEC 3731 tester . Why is there current on water pipe grounds usually ?
Click to expand...
Sounds normal. Some of the neutral current is returning on the water pipe to the neighbors service which is also bonded to the same piping system.
 
MIcAngelo said:
Hello Everyone I have a question. I am in a 6000 sq foot building for over 35 years. It used to be a factory. I have a 3 phase service coming into my building 120/120/208 + neutral . I think it's called a Delta Wye. As soon as the 4 wires enter the building, they go into an enclosed electrical box whereby they are each doubled so they can split off to 8 wires.

4 wires go straight up to a mains panel with 200 amp main breaker and the other 4 wires go to a large disconnect with fuses. IN this large disconnect the neutral meets the case of the disconnect metal shell and the water pipe ground. the output of that goes to a 100 amp sub panel ..

The main 200 amp breaker panel does not have the neutral bonded to its case , (just like my sub panel) is this ok? or should I connect the mains 200 amp breaker panel from the large disconnect where the other sub panel comes from?
Click to expand...

If I understand correctly, you're describing a service with two disconnects. Both service disconnects require neutral to be bonded to the case and equipment grounds, i.e. a Main Bonding Jumper. You've described the 200A panel not having this. You should have an electrician verify if this is true and fix it if it's true.


MIcAngelo said:
Well, to be honest, there was a huge Sonic improvement in our Mastering room when we added the deep earth grounding to the water pipe ground. But I have another question? my electrician measured current on the water pipe ground about 3.8 A. Using the AMEC 3731 tester . Why is there current on water pipe grounds usually ?
Click to expand...
MIcAngelo said:
And by the way, my water pipe ground has a very low impedance of 1.8 ohms and there is no plastic conduit between my building and the water mains in the street
Click to expand...
The lower the electrode impedance, the more current will flow on it. As others have said this is normal.
 
His recording studio looks like an 80 by 80 foot stand-alone building with four air conditioner units out back.
I wonder if it has 3 phase power?
 
Retired Audio Engineering Society noise and interference expert Jim Brown wrote:

HIGH LEG DELTA
Figure A-6 shows a variation of the delta configuration that is widely used in North
America, especially in older mixed residential and industrial areas, and in rural areas.
One leg of the delta has a grounded center-tap that serves as the neutral for a single-
phase 120/240VAC system, and 208 volts is available for certain industrial applications.
Also known as a Red Leg Delta, or Wild Leg, High Leg Delta systems must have that
phase conductor marked with orange tape, orange finish or similar. This marking is only
required where a connection is made and the neutral conductor is present.
The configuration can work for audio and video systems if there are no other loads on
the transformer. But EMC consultant Neil Muncy has taught us that when High Leg
Delta is used to feed multiple customers from the same transformer, the neutral cur-
rents from one customer can circulate through another customer’s ground system.
When this happens, the neutral feed from the pole-mounted transformer may carry
relatively large neutral currents from those neighboring buildings.
The neutral current will find its way to earth through the system earth at the service en-
trance, and in general, the better the earth electrode system, the greater the circulating
current will be! If the path to earth runs near audio equipment or wiring, the magnetic
fields produced by these currents can couple into system wiring, guitar pickups and
dynamic microphones without hum-bucking coils, and even the electronics of audio
gear. The result is hum and buzz that can be eliminated only by eliminating the field.
The hum component is 60 Hz, while the “buzz” consists of harmonics. When called in
to diagnose problems in a small recording studio complex in a renovated industrial
building, Muncy found a High Leg Delta power feed with 7A of neutral current finding
its return path via a water main running under the guitar isolation booth!
The solution is to use a transformer with a single-phase center-tapped secondary (Fig-
ure 1), to feed 120/240 v systems in the building, powering it from one of the un-
grounded 240 volt phases. What matters is that the shared neutral feed to the building,
with the offending currents, must be eliminated.
 
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