Ground-neutral bonding issue

[Richardtheelectrician]

I know the code requires that the ground and neutral wire of an electrical service be separate conductors except at the main service disconnect. I also know that the majority of houses out there were wired under a different code rule. So when I do service calls, i see this violation constantly.
I am not a theoretician, I am a nuts and bolts guy. What is the danger exactly to this old wiring method, and how do I honestly upsell a customer on installing a dedicated ground bar in their branch circuit panel?
Thanks kindly.
RM.

 

[jaylectricity]

Just to clear a few things up, the neutral and ground are required to be bonded at the first overcurrent device, then separated from that point on.

I think your best bet for this particular upsell is being able to point out that it will make things easier for all future installations. If you can get all the grounds on their own ground bar and rearrange all the neutrals so they correlate to their breakers it make things much easier to land new circuits in the panel.

As you say, you're a nuts and bolts guy, so make the sell about making future installations easier.

Now if you're talking about a sub-panel that has it's grounds and neutrals bonded I think the nuts and bolts of it is, if the metal cabinet is bonded to the neutral at that spot, there's a potential for electricity to find a path through somebody touching the cabinet and ground, if there's a ground nearby. That would include water pipes, or a sink, or cement floors and walls.

 

[Richardtheelectrician]

Thanks, Jay.

Thanks, Jay.

But at this point I see no real world necessity to trying to sell the change. I would be happy to be proven wrong.

 

[hurk27]

A sub panel close to the main service panel/disconnect yes it would be hard to define a safety problem other then the fact that loosing the neutral ahead of this sub panel will put 120 volts to all that is grounded to this panel but the same could be said of every main service panel except that in many cases there would be a water bond that would limit the voltage if the water pipe is also connected to the neighbors house neutral, a sub panel would not have this back up, but a sub panel located 20 feet or more from the main would also have a voltage drop issue because the voltage drop of the neutral will be on everything grounded to this sub panel, now we might not think having 2 or 3 volts voltage drop to be dangerous but lets say that there is a hot tub or swimming pool fed off this sub panel, well it only takes 1 volt to prevent your mussels from being able to get yourself out of a body of water when you are submerged, and very little more to prevent you from being able to maintain flotation or keeping your head above water, and the fact that using the neutral as a ground after the main service bond will also allow much higher voltages if you happen to be standing upon earth or touching something that is at earth potential while touching a grounded electrical appliance at the time of a fault to ground or neutral happens, the fault current can be in the hundreds of amps and the voltage drop then produced on the neutral will be much higher and would also be on everything grounded to this sub panel, so this is not just because some thought it was allowed way back when, because it was never a accepted code practice, it has always been against code to use the neutral for grounding after the MBJ except in a couple areas (ranges and dryers) and remote garages to which both have been removed from being allowed.

but if you want a simple way to explain to a home owner that this should be address is many insurance company's who have their own inspection can refuse to insure property if it doesn't meet code and considered unsafe, and also if they plan to sell the property in the near future let them know this will be flagged by a HI and can possibly stop a sale or at least cause the buyer to ask for a lower price.

 

[ActionDave]

I know the code requires that the ground and neutral wire of an electrical service be separate conductors except at the main service disconnect. I also know that the majority of houses out there were wired under a different code rule. So when I do service calls, i see this violation constantly.
I am not a theoretician, I am a nuts and bolts guy. What is the danger exactly to this old wiring method, and how do I honestly upsell a customer on installing a dedicated ground bar in their branch circuit panel?
Thanks kindly.
RM.

Are you talking about wiring to a sub-panel to a separate building or to a sup-panel in the same building. What is this different code rule?

With multiple neutral to ground connections you could be using uninsulated parts of the electrical system to carry current.

 

[Richardtheelectrician]

Talking about a house (eighty million of them) that have ground and neutral bonded together. In their garage. Below the main at the meter.

 

[ActionDave]

That's not the worst thing, but it must have been allowed by local custom.

 

[hurk27]

Talking about a house (eighty million of them) that have ground and neutral bonded together. In their garage. Below the main at the meter.

If we are talking about a detached garage then this was allowed by code until 2008, not sure what you mean "below the main at the meter? if the garage has a service with meter then you are required to have a main bonding jumper because it is a service??? even the 2008 allows it still for existing, see in the 2008 NEC 250.32(B) exception the 2005 NEC 250.32(B)(2) allowed it if no other paths existed between the buildings

If we are talking about an attached garage then that is a different story, but remember many garages that are attached today were not attached and they built in between the house and garage.

Heres one for you, many times when I know I will have an out building such as a garage and know they will want at least a 100 amp panel in it, I will install a double lug meter base that has double lugs on the load side of the meter, I will run from these extra lugs back down into the ground over to the garage up into an LB into a main breaker panel with just 2 hots and a neutral, the code will treat these conductors as service entrance conductors so the neutral is bonded to the grounding at the garage and is code compliant even today you save on conductors and having to have a feeder breaker at the house panel, very code compliant.

 

[hurk27]

Talking about a house (eighty million of them) that have ground and neutral bonded together. In their garage. Below the main at the meter.

If we are talking about a detached garage then this was allowed by code until 2008, not sure what you mean "below the main at the meter? if the garage has a service with meter then you are required to have a main bonding jumper because it is a service??? even the 2008 allows it still for existing, see in the 2008 NEC 250.32(B) exception the 2005 NEC 250.32(B)(2) allowed it if there were no other continuous metallic paths between the building


If we are talking about an attached garage then that is a different story, but remember many garages that are attached today were not attached and they built in between the house and garage.

Heres one for you, many times when I know I will have an out building such as a garage and know they will want at least a 100 amp panel in it, I will install a double lug meter base that has double lugs on the load side of the meter, I will run from these extra lugs back down into the ground over to the garage up into an LB into a main breaker panel with just 2 hots and a neutral, the code will treat these conductors as service entrance conductors so the neutral is bonded to the grounding at the garage and is code compliant even today you save on conductors and having to have a feeder breaker at the house panel, very code compliant.

 

[Twoskinsoneman]

If we are talking about a detached garage then this was allowed by code until 2008, not sure what you mean "below the main at the meter? if the garage has a service with meter then you are required to have a main bonding jumper because it is a service??? even the 2008 allows it still for existing, see in the 2008 NEC 250.32(B) exception the 2005 NEC 250.32(B)(2) allowed it if there were no other continuous metallic paths between the building


If we are talking about an attached garage then that is a different story, but remember many garages that are attached today were not attached and they built in between the house and garage.

Heres one for you, many times when I know I will have an out building such as a garage and know they will want at least a 100 amp panel in it, I will install a double lug meter base that has double lugs on the load side of the meter, I will run from these extra lugs back down into the ground over to the garage up into an LB into a main breaker panel with just 2 hots and a neutral, the code will treat these conductors as service entrance conductors so the neutral is bonded to the grounding at the garage and is code compliant even today you save on conductors and having to have a feeder breaker at the house panel, very code compliant.

A fine idea.

230.40 Exception No. 3: A single-family dwelling unit and itsaccessory structures shall be permitted to have one set of
service-entrance conductors run to each from a single service
drop, set of overhead service conductors, set of underground
service conductors, or service lateral.