SINGLE POINT GROUNDING - Starts at the Sub Stations

[mtnelect]

The utilities would not like this ... It would cost them more MONEY to install a dedicated neutral from the local neighborhood substation to the end of each local circuit. And it would reduce the amount of current that is presently being pumped into the ground.

Presently, it's the homeowner who has to deal with all of this "Stray Current" floating around everywhere, which is dangerous to animals and humans. Not to mention the requirement of ponding ground rods everywhere !

Also, it would do away the ridiculous grounded connection between the primary and secondary at every pole transformer.

 

[mtnelect]

Also, the service drop neutral would now be insulated.

 

[LarryFine]

The utilities would not like this ... It would cost them more MONEY to install a dedicated neutral from the local neighborhood substation to the end of each local circuit. And it would reduce the amount of current that is presently being pumped into the ground.

Presently, it's the homeowner who has to deal with all of this "Stray Current" floating around everywhere, which is dangerous to animals and humans. Not to mention the requirement of ponding ground rods everywhere !

Also, it would do away the ridiculous grounded connection between the primary and secondary at every pole transformer.

I really don't understand what you think could or should be done, or done differently.

Not only are the primary and secondary neutrals connected, they're often the same conductor.

 

[mtnelect]

I really don't understand what you think could or should be done, or done differently.

Not only are the primary and secondary neutrals connected, they're often the same conductor.

I will count you satisfied with the present MNG systems ?

 

[LarryFine]

I will count you satisfied with the present MNG systems ?

Yeah. I grew up on it, and I'm kinda used to it. Plus, I have never encountered a problem with it.

Seriously, what do you propose would be a better system? How would it be wired differently?

 

[kwired]

The utilities would not like this ... It would cost them more MONEY to install a dedicated neutral from the local neighborhood substation to the end of each local circuit. And it would reduce the amount of current that is presently being pumped into the ground.

Presently, it's the homeowner who has to deal with all of this "Stray Current" floating around everywhere, which is dangerous to animals and humans. Not to mention the requirement of ponding ground rods everywhere !

Also, it would do away the ridiculous grounded connection between the primary and secondary at every pole transformer.

I really don't understand what you think could or should be done, or done differently.

Not only are the primary and secondary neutrals connected, they're often the same conductor.

unless everyone used ground fault protective devices on pretty much everything you would still have current on the grounding conductors any time someone didn't "follow the rules" or had unintended current on the grounding conductor.

You would still have bonding at every separately derived system and chances of stray currents should something go wrong.

I still think things like swimming pools should require equipotential bonding even if such distribution were utilized, problems won't be as bad but still is possible to have voltage gradients within the pool.

 

[mtnelect]

Another problem with the "MNG" system is that the utilities "Lightning Arresters" when activated have a great low impedance path to everyone's service !

 

[LarryFine]

Another problem with the "MNG" system is that the utilities "Lightning Arresters" when activated have a great low impedance path to everyone's service !

Could you say that home SPDs can do the same thing?

 

[mtnelect]

Could you say that home SPDs can do the same thing?

My understanding is that SPD are not fast acting enough to protect the service anyway ... They just self-destruct and leave a big burn mark on your service.

 

[kwired]

Another problem with the "MNG" system is that the utilities "Lightning Arresters" when activated have a great low impedance path to everyone's service !

Further away you are the more impedance and more current flows to local grounding electrodes than to remote ones. If your transformer pole is what took the strike, you are likely to have some damage either way. If pole a mile down the road is what gets hit, you may see some surge on the line, your whole house protector or even most your individual equipment surge protectors likely safely dissipate that surge.

Here on rural distribution you see lighting arrestors on maybe every 3rd to 5th pole if there is no other equipment in that distance. Otherwise pretty much every pole with a transformer/transformer bank or even with a tap to under ground primary lines likely is going to have lightning arrestors on it. Single phase pole mounted transformers with 120/240 secondary usually have lightning arrestor as a part of the transformer or at least an add on item that is attached to the transformer.

 

[zbang]

What problem are you trying to solve and is there a rational solution? Please state them clearly.

Anyway, lots of people, maybe even the vast majority, never have problems with/from the utility MGN system and don't have to deal with "all of this 'Stray Current' floating around everywhere"...

Right here...lessee- water line has dielectric union at the meter, gas line has dielectric union, most of the waste line is plastic. Where's the problem?

 

[mtnelect]

You brought up another good point about why the utilities like the "MNG" system ... All the equipment that is used on an "MNG" system is cheaper because they are rated at a lower working potential.

 

[mtnelect]

What problem are you trying to solve and is there a rational solution? Please state them clearly.

Anyway, lots of people, maybe even the vast majority, never have problems with/from the utility MGN system and don't have to deal with "all of this 'Stray Current' floating around everywhere"...

Right here...lessee- water line has dielectric union at the meter, gas line has dielectric union, most of the waste line is plastic. Where's the problem?

The "MNG" system has a higher deployment of "Stray Current" being pumped into the ground than "Single Point Grounding" systems.

 

[kwired]

What problem are you trying to solve and is there a rational solution? Please state them clearly.

Anyway, lots of people, maybe even the vast majority, never have problems with/from the utility MGN system and don't have to deal with "all of this 'Stray Current' floating around everywhere"...

Right here...lessee- water line has dielectric union at the meter, gas line has dielectric union, most of the waste line is plastic. Where's the problem?

If that water line is metallic NEC would still require you place a jumper around the dielectric union and using that buried metallic line as a grounding electrode - sort of making said union pointless.

It causes problems most of them for livestock farming operations, dairy farms in particular. Yes there is rather limited number of such facilities. There also is equipotential bonding rules in art 547 that help lessen the problems. It also causes voltage gradient issues at marinas and other docks with anything connected to the electrical grounding network on the docks. GFCI does not protect against those issues as it doesn't protect grounding conductors in any way just the current carrying conductors. Would be a much bigger issue at swimming pools if we didn't have rules for equipotential bonding there as well. Bottom line is the stray currents are still there we are just building a Faraday cage out of the pool to make those currents go around the users. A hole in the cage does cause problems when it occurs though.

 

[mtnelect]

If that water line is metallic NEC would still require you place a jumper around the dielectric union and using that buried metallic line as a grounding electrode - sort of making said union pointless.

It causes problems most of them for livestock farming operations, dairy farms in particular. Yes there is rather limited number of such facilities. There also is equipotential bonding rules in art 547 that help lessen the problems. It also causes voltage gradient issues at marinas and other docks with anything connected to the electrical grounding network on the docks. GFCI does not protect against those issues as it doesn't protect grounding conductors in any way just the current carrying conductors. Would be a much bigger issue at swimming pools if we didn't have rules for equipotential bonding there as well. Bottom line is the stray currents are still there we are just building a Faraday cage out of the pool to make those currents go around the users. A hole in the cage does cause problems when it occurs though.

The utilities caused this problem of "Stray Current", and they should pay for it ... Not the homeowners !

 

[kwired]

The utilities caused this problem of "Stray Current", and they should pay for it ... Not the homeowners !

The consumers ultimately pay for it anyway. You do realize such an upgrade to the entire grid is very likely to make your utility bill go up. Minor maintenance and upgrades here and there are not something that would rais the consumers bills.

There may be some that don't use a wye secondary on their distribution but still have common grounding across the entire network and there can be grounded conductor currents on that grounding network though there won't be any primary neutral contributions to the net voltage on the grounded service conductor to earth at a customer's service.

 

[mtnelect]

The utilities are more concerned about delivering cheap power than "Stray Current" that is dangerous to animals and humans. There has been a lot of talk about our vulnerable "Electrical Infrastructure". If and when that should happen, that would be the appropriate time to implement a "Single Point Grounding" system.

 

[zbang]

I'll guarantee that most utilities are more concerned with MAKING MONEY and keeping just inside the reg's than anything else, including "stray currents". (Investor-owned will act differently than publicly or customer owned.)

Where's the business case for a massive renovation of the transmission and distribution systems? And I don't see this sort of change as a reliability enhancement, if it is, how?

Have we heard the engineers who design and maintain these systems chime in about what such a massive change would entail and improve (other than making a lot of work and enriching the copper companies)?

Heck, I'd just like to hear about where and how often the use of MGN causes actual, not perceived, problems. As mentioned above, dairy farms, around some bodies of water, inc pools, but how does that compare to the rest of the service area? Does it make sense to move away from MGN in specific areas or everywhere? (If a county has one lake with one dock and no livestock farms, how much sense does it make to re-engineer the entire distribution system for that county?)

 

[ActionDave]

I think we should transition to all loads being line to line. Over time the neutral load fades away.

 

[winnie]

It isn't only about being cheap by not having a separate insulated neutral.

There is also the benefit of 'effective grounding', tying phase voltages in closer reference to local earth voltage by having regular connection between phase and earth via transformer coils.

This could be done with greater attention to balance, which would reduce injection of current onto the common ground/neutral. And such attention to balance would cost more. So this isn't a strict binary.

But in this discussion do remember that there is value to the customer from the earth connection.

Jonathan