Meter Enclosure Grounding

[Pierre C Belarge]

Well the utility commissions should do something about this. Let the utility lock the service disconnects if they want to. But if they're gonna do that then they might as well provide the disconnect as well as the meter. TOUGH BANANA!!! People's safety is at stake.

Eric
Your tagline states: "if it's not broken don't fix it"


I am not aware of anyone injuries or deaths to the customer from the current location of the meter equipment being located ahead of the disconnect.

 

[erickench]

Nevertheless the chance of somebody being killed or injured is still there. If only they came up with a way to remote control the OCPD. The utility can turn it on or off at will.

 

[iwire]

Nevertheless the chance of somebody being killed or injured is still there.

Yes there is a chance.


Check out 230.90(A) Exception 3 and consider what that allows. It is not directly related to the meter subject but it is another area where service conductors and equipment can be overloaded to the point of fire.

 

[Pierre C Belarge]

Nevertheless the chance of somebody being killed or injured is still there.

Is that not generally true with any electrical installation?

 

[erickench]

Our job as professionals is to reduce the chance of injury whenever possible. I've seen too many bad drawings over the years that were in direct violation of the NEC. I'm not gonna be quiet about it.

 

[erickench]

NEC 230.90(A) Exception No. 3 looks like a real problem. The service conductors have no overload protection.

 

[Pierre C Belarge]

NEC 230.90(A) Exception No. 3 looks like a real problem. The service conductors have no overload protection.

Eric
I am not knocking you here, but how long have you been in the industry?

These types of installations have been standard practice for a very long time. Again, I will state that I am not aware of any issues these types of installations have caused for the customer.

I understand your concern for safety, and I am glad to see it. Electricity has an inherent danger to it, even for consumers.
I do believe many more people are killed each year driving cars, and less people drive cars, then use electricity.

 

[iwire]

NEC 230.90(A) Exception No. 3 looks like a real problem. The service conductors have no overload protection.

Exactly my point it looks like a problem but in fact is a very frequently used exception in multifamily dwellings and commercial services.

It counts on future installers to do load calculations and not exceed the rating of the service entrance conductors.


Here is an example of that exception in action

Each of those meters supplies a 100 amp breaker but the riser is only in the 200 to 250 amp range.

 

[erickench]

I've been in the industry for 25 years. I've made a career out of finding mistakes on drawings and specs. Working down in the subways as a construction inspector I've come across drawings that either look ridiculous or actually changed a pre-existing condition and made it worse than what it was before. But this is a case where there is a chance of danger and should not be ignored. That 'YouTube' that Bob(iwire) posted convinced me that this is a serious problem.

 

[erickench]

Exactly my point it looks like a problem but in fact is a very frequently used exception in multifamily dwellings and commercial services.

It counts on future installers to do load calculations and not exceed the rating of the service entrance conductors.


Here is an example of that exception in action

Each of those meters supplies a 100 amp breaker but the riser is only in the 200 to 250 amp range.

Bob, let me relate to you an experience I had back in 1998 while inspecting a contractor doing work inside TA substations. I saw a sketch made by a designer that had a single unprotected 500MCM cable running from the service conductor and then branching into two 500 MCM cables with a 400A circuit breaker on each. Now if the current and been at full load for each of these taps there would have been 800A flowing through a single 500MCM cable. This cable was in a metal conduit installed on a high ceiling inside the substation and ran from one end of the station to the other.

 

[iwire]

Bob, let me relate to you an experience I had back in 1998 while inspecting a contractor doing work inside TA substations. I saw a sketch made by a designer that had a single unprotected 500MCM cable running from the service conductor and then branching into two 500 MCM cables with a 400A circuit breaker on each. Now if the current and been at full load for each of these taps there would have been 800A flowing through a single 500MCM cable. This cable was in a metal conduit installed on a high ceiling inside the substation and ran from one end of the station to the other.

If the NEC applied to that installation it would only be in violation for the distance it ran inside the building.

If the installation was outside or made to comply with the rules found in 230.6 and the total calculated load was less than the capacity of the conductors it would be NEC compliant.

Many times in commercial work you will find that the service conductors supply a main lug only panel with up to six breakers used as the service disconnecting means. The total combined rating of all the switches will normally far exceed the service conductor and bus ratings.

One of the places I used to work at had about 1600 amps of service conductors 'protected' by 3000 amps of breakers ......... however that service also complied with 230.6 and the calculated load was lower than the conductor rating.

It is a very common installation and one I have no first hand knowledge of failure with even though I do agree it appears to be a dangerous situation.

 

[erickench]

Here's another TA disaster that I worked on in the 1990's. Somebody paid dearly when I blew the whistle on this one. I came across a drawing with a fudged note on it. The note called for two parallel 500 MCM cables to be spliced with a single 250 MCM that was connected to a motor in a subway tunnel. I tried to correct the problem by giving direction to the foreman but some idiot overruled me. The job was ruined as a result. Now I don't know if there is such a thing as a motor tap. But this configuration only had one tap and that's what made it look so strange.