winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
I have a dear friend from college who is completely disabled by 'Electromagnetic Hyper Sensitivity'. Your writing strongly reminds me of him in a manic phase. That is to say: long winded, somewhat misdirected, with some important kernels of truth.
Your profile suggests that you are providing some sort of consulting service to help mitigate emfs, but it sure sounds like you are writing about your own home.
I accept the possibility that magnetic fields from unbalanced current flows may cause harm. I accept the reality that some people are deeply troubled by the presence of such magnetic fields. The reality of harm caused by electric _shock_ or fire is well known, and any changes to an electrical system to reduce unbalanced current flows must not increase the risk of shock or fire.
The suggestion for how to eliminate the current flow path has already been made. Eliminate the common metallic pipe system.
Code requires that interior metallic water piping be bonded to the system neutral. But an _isolated_ metallic water pipe system with a connection to a single point on the electrical system neutral will not have current flow and will not produce magnetic fields.
Code requires that _all_ available grounding electrodes be used to ground the system neutral. Included in the list of available grounding electrodes are underground water pipes. A very small amount of current will flow via these grounding electrodes through the soil. There is no practical way to eliminate this, unless you want to invest in transformer located in the home...and that transformer will produce significant magnetic fields.
The problem is _common_ underground metallic piping. These provide a continuous _metallic_ path between homes, and thus provide a continuous _metallic_ path parallel to the home neutral connections.
Lots of current can flow on this metallic parallel path, and this results in large magnetic fields surrounding the metallic pipes, the grounding electrode conductors to those pipes, and the service entrance conductors.
The best solution is to replace some portion of the underground pipe bringing water into the home. This eliminates the continuous metallic path joining one neutral to the others. You don't need to replace the entire underground run of pipe, you don't need to replace the water main. Simply a long enough section of the pipe between the home and the main to 'break' the continuous metallic path between houses.
The portion of pipe replaced need not be very large. Depending upon the location this may render the pipe 'no longer an acceptable grounding electrode', or it may permit the use of a portion of the pipe as a grounding electrode, but eliminate the continuous metallic path. Without the water pipe ground, additional grounding electrodes may need to be added.
Essentially: if you have that common underground metallic piping, code requires you to use it, but code does not require you to have the common underground metallic piping. So you eliminate the _metallic_ pipe and eliminate the code requirement to use it.
There would still be a 'parallel path' via the soil surrounding the grounding electrodes, but this is a high resistance path and thus there will be much lower current flow.
You are correct: that common underground water pipe provides protection from an 'open neutral' situation, because the water pipe can act as a backup neutral. However this backup neutral is _not_ something required by code. Code does not require the use of common underground water piping. It requires that a metal water pipe of certain length going into the home be used as a grounding electrode. _Grounding_ is not considered a suitable backup for the neutral.
Something that you mentioned is that your service conductors are underground. I think this changes the merit of your 'redirection' proposal. If you can route the grounding electrode conductor in close proximity to the service conductors, then any unbalanced current flowing on the GEC would balance and cancel out the unbalanced current on the service entrance conductors. This is something that would need to be evaluated by a careful site survey.
-Jon
Your profile suggests that you are providing some sort of consulting service to help mitigate emfs, but it sure sounds like you are writing about your own home.
I accept the possibility that magnetic fields from unbalanced current flows may cause harm. I accept the reality that some people are deeply troubled by the presence of such magnetic fields. The reality of harm caused by electric _shock_ or fire is well known, and any changes to an electrical system to reduce unbalanced current flows must not increase the risk of shock or fire.
The suggestion for how to eliminate the current flow path has already been made. Eliminate the common metallic pipe system.
Code requires that interior metallic water piping be bonded to the system neutral. But an _isolated_ metallic water pipe system with a connection to a single point on the electrical system neutral will not have current flow and will not produce magnetic fields.
Code requires that _all_ available grounding electrodes be used to ground the system neutral. Included in the list of available grounding electrodes are underground water pipes. A very small amount of current will flow via these grounding electrodes through the soil. There is no practical way to eliminate this, unless you want to invest in transformer located in the home...and that transformer will produce significant magnetic fields.
The problem is _common_ underground metallic piping. These provide a continuous _metallic_ path between homes, and thus provide a continuous _metallic_ path parallel to the home neutral connections.
Lots of current can flow on this metallic parallel path, and this results in large magnetic fields surrounding the metallic pipes, the grounding electrode conductors to those pipes, and the service entrance conductors.
The best solution is to replace some portion of the underground pipe bringing water into the home. This eliminates the continuous metallic path joining one neutral to the others. You don't need to replace the entire underground run of pipe, you don't need to replace the water main. Simply a long enough section of the pipe between the home and the main to 'break' the continuous metallic path between houses.
The portion of pipe replaced need not be very large. Depending upon the location this may render the pipe 'no longer an acceptable grounding electrode', or it may permit the use of a portion of the pipe as a grounding electrode, but eliminate the continuous metallic path. Without the water pipe ground, additional grounding electrodes may need to be added.
Essentially: if you have that common underground metallic piping, code requires you to use it, but code does not require you to have the common underground metallic piping. So you eliminate the _metallic_ pipe and eliminate the code requirement to use it.
There would still be a 'parallel path' via the soil surrounding the grounding electrodes, but this is a high resistance path and thus there will be much lower current flow.
You are correct: that common underground water pipe provides protection from an 'open neutral' situation, because the water pipe can act as a backup neutral. However this backup neutral is _not_ something required by code. Code does not require the use of common underground water piping. It requires that a metal water pipe of certain length going into the home be used as a grounding electrode. _Grounding_ is not considered a suitable backup for the neutral.
Something that you mentioned is that your service conductors are underground. I think this changes the merit of your 'redirection' proposal. If you can route the grounding electrode conductor in close proximity to the service conductors, then any unbalanced current flowing on the GEC would balance and cancel out the unbalanced current on the service entrance conductors. This is something that would need to be evaluated by a careful site survey.
-Jon
