service equipment

jap

Senior Member
Sometimes it is nearly impossible to run a new cable for a range or dryer. The inspectors here look at situations like this and will allow taping of a bare neutral to prevent accidental contact with anything non-current carrying.
And that's just silly.

JAP>
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
That's an interesting point.

Seeing as how there is no branch distribution in a Meter/Main setup (unless you purchase it with it) , isn't the existing Service Panel (although now actually a subpanel) still the first "Service Panel" where a branch circuit can be taken from ?


JAP>
No, service equipment is still where the Main Disconnect is located, we can't change the article 100 definition because it doesn't fit our needs. There is nothing requiring branch circuits to be fed from the service Main, think about a NEMA 3 disconnect outside the dwelling unit being the Main, after you leave the disconnect the lighting and appliance branch-circuit panelboard(s) is/are a subpanel(s).


Roger
 

jap

Senior Member
No, service equipment is still where the Main Disconnect is located, we can't change the article 100 definition because it doesn't fit our needs. There is nothing requiring branch circuits to be fed from the service Main, think about a NEMA 3 disconnect outside the dwelling unit being the Main, after you leave the disconnect the lighting and appliance branch-circuit panelboard(s) is/are a subpanel(s).


Roger
I thought I saw a post where the exception indicated Service "Panel".

I may be mistaken.

I agree it needs to be re-worded somewhat.

JAP>
 

jap

Senior Member
Here it is,

the requirement that a three wire branch circuit as covered in 250.140 must originate at the "Service Equipment"


To me the only way you could use this exception would be if the Service Panel had the first OCPD incorporated into it, or, additional service disconnects were installed strictly to reefed the existing 3 wire circuits with no more than a total of 6.


JAP>
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Dennis, I would like to hear what Joe has to say about it not being fed from the service equipment. Regardless, NC's amendments do not change the NEC which does not have any exception to the requirement that a three wire branch circuit as covered in 250.140 must originate at the "Service Equipment"

Roger
I've had this discussion many times. It does not say that you can't feed a range or dryer from a subpanel with a 3-wire cable. It's saying that if the grounded conductor is uninsultated and part of an SE cable then it has to originate from the service equipment. A 3-wire cable with an insulated grounded conductor can be ran from a subpanel.
Notice the comma highlighted in red below. That is the first part of the sentence and everything past that is the rest of the sentence. Then notice the two "and"s, highlighted in red. The "ands" go with only the second part of the sentence. There would be no need to include "insulated" if all 3-wire cables had to originate from the service.

So insulated grounded conductor that is part of a 3-wire cable, good to go from sub
Uninsulated grounded conductor from an SE 3-wire has to come from service panel



The grounded conductor is insulated, or the grounded conductor
is uninsulated and part of a Type SE service-entrance cable and
the branch circuit originates at the service equipment.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I've had this discussion many times. It does not say that you can't feed a range or dryer from a subpanel with a 3-wire cable. It's saying that if the grounded conductor is uninsultated and part of an SE cable then it has to originate from the service equipment. A 3-wire cable with an insulated grounded conductor can be ran from a subpanel.
Notice the comma highlighted in red below. That is the first part of the sentence and everything past that is the rest of the sentence. Then notice the two "and"s, highlighted in red. The "ands" go with only the second part of the sentence. There would be no need to include "insulated" if all 3-wire cables had to originate from the service.

So insulated grounded conductor that is part of a 3-wire cable, good to go from sub
Uninsulated grounded conductor from an SE 3-wire has to come from service panel

I don't think Roger was arguing that. It was when a seu not ser cable was used from a main panel and then one converted the main panel into a sub. The nec does not allow that since the concept of existing is not the same with the transformation made.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
I don't think Roger was arguing that. It was when a seu not ser cable was used from a main panel and then one converted the main panel into a sub. The nec does not allow that since the concept of existing is not the same with the transformation made.
Bill, Dennis is correct and is the reason I wanted to clarify it in post 13.

Roger
 

kwired

Electron manager
Location
NE Nebraska
'Subpanel' is not a code term but the way myself and everyone else I know uses the term it is by definition not service equipment. In fact I would say it's primarily used to communicate that a panel is not service equipment.

I completely agree with Dennis regarding changing the role of a panel.
Subpanel is not a code term. There is services and everything ahead of the service disconnecting means following rules that require bonding non current carrying items to the "grounded conductor". At the service disconnecting means we install a main bonding jumper and beyond that we keep separate EGC's and grounded conductors beyond that point, with some exceptions for existing items that once were compliant that way. Beyond the service disconnecting means we have either feeders or branch circuits - those "sub panels" are supplied by feeders and no rules for services apply to them anymore. You move the service disconnect from the "panel" to out by/at the meter, you turned it into a feeder supplied panel when before it was a service supplied panel.

Sometimes it is nearly impossible to run a new cable for a range or dryer. The inspectors here look at situations like this and will allow taping of a bare neutral to prevent accidental contact with anything non-current carrying.
Yet the frame of the appliance is still at same potential as the "grounded conductor" whether you taped the bare conductor or not, presuming you installed the bonding jumper in the appliance.
 

mortimer

Member
Location
newengland
So......The HO will not pay for the EC to change the 3 wire in his new "sub panel" to a 4 wire for his range, that has a #6 seu after changing the old service to a meter main.
What is an inspector to do :?
 

roger

Moderator
Staff member
Location
Fl
Occupation
Electrician
Don't sign off on the permit, it will be between the EC and the HO. If they decide to sell the home it will come back to the surface.

IMO, the EC should have caught it and included the fix in his proposal.

Roger
 

hornetd

Senior Member
Location
Maryland
Feeder Supplied Panels

Feeder Supplied Panels

'Subpanel' is not a code term but the way myself and everyone else I know uses the term it is by definition not service equipment. In fact I would say it's primarily used to communicate that a panel is not service equipment.

I completely agree with Dennis regarding changing the role of a panel.
Any panelboard that is supplied via conductors which originate in another panel and are not tapped off of the Service Entry Conductors is a feeder supplied panel. Once the current passes through a Service Disconnecting means any circuit it supplies is either a Branch Circuit or a Feeder. Any panelboard supplied by a feeder circuit cannot by definition be Service Equipment. All Service Equipment is supplied by Service Entry Conductors or by a power utility underground service lateral which is terminated directly on the supply terminals of the Service Disconnecting Means. That last is essentially a semantic difference that comes about because of the difference in Service Standards between different power utilities. Those standards; once they are accepted by the utility regulatory agency of a state government; define were the demarcation point is between the Utility's conductors and the premises Service Entry Conductors. When a service lateral terminates at the supply terminals of a Meter Mains assembly that is the demarcation point and there are no Service Entry Conductors.
 
Last edited:

jap

Senior Member
Any panelboard that is supplied via conductors which originate in another panel and are not tapped off of the Service Entry Conductors is a feeder supplied panel. Once the current passes through a Service Disconnecting means any circuit it supplies is either a Branch Circuit or a Feeder. Any panelboard supplied by a feeder circuit cannot by definition be Service Equipment. All Service Equipment is supplied by Service Entry Conductors or by a power utility underground service lateral which is terminated directly on the supply terminals of the Service Disconnecting Means. That last is essentially a semantic difference that comes about because of the difference in Service Standards between different power utilities. Those standards; once they are accepted by the utility regulatory agency of a state government; define were the demarcation point is between the Utility's conductors and the premises Service Entry Conductors. When a service lateral terminates at the supply terminals of a Meter Mains assembly that is the demarcation point and there are no Service Entry Conductors.
Let's not forget.

It can only be considered a branch circuit or feeder after it passes through some type of OCPD.

JAP>
 

hornetd

Senior Member
Location
Maryland
Sometimes it is nearly impossible to run a new cable for a range or dryer. The inspectors here look at situations like this and will allow taping of a bare neutral to prevent accidental contact with anything non-current carrying.
Taping a neutral on a 3 wire range or dryer circuit is only of use in the panel from which the 3 wire branch circuit originates. That still does not address the underlying problems arissing out of such installations remaining in service once the panel it originates in is no longer the Service Equipment. The frame of the appliance will be bonded to the Grounded Current Carrying Conductor (Neutral) if that appliance was properly installed in the first place. Metal reinforced water supply hoses, contact with an adjacent appliance, or being on a conductive floor, such as concrete, if the legs are conductive will all provide a sneak current pathway for neutral current to flow over exposed conductive surfaces. The controls of a range and the motor and controls of a clothes dryer all require a 120 volt supply. In both cases that guarantees that there will be current flowing on the Grounded Current Carrying Conductor (Neutral). As long as the connections of the Grounded Current Carrying Conductor (Neutral) remain in good condition most of the current from the 120 volt portion of the load will return on the Grounded Current Carrying Conductor (Neutral). If any connection of the Grounded Current Carrying Conductor (Neutral) becomes high resistance for any reason that current will be looking for a way back to the windings of the secondary of the transformer from whence it came that was never intended to carry electrical current. It is nearly inevitable that the leakage pathway will have considerable voltage drop and that the touch potential of some conductive surfaces will become dangerous.
 

jap

Senior Member
Taping a neutral on a 3 wire range or dryer circuit is only of use in the panel from which the 3 wire branch circuit originates. That still does not address the underlying problems arissing out of such installations remaining in service once the panel it originates in is no longer the Service Equipment. The frame of the appliance will be bonded to the Grounded Current Carrying Conductor (Neutral) if that appliance was properly installed in the first place. Metal reinforced water supply hoses, contact with an adjacent appliance, or being on a conductive floor, such as concrete, if the legs are conductive will all provide a sneak current pathway for neutral current to flow over exposed conductive surfaces. The controls of a range and the motor and controls of a clothes dryer all require a 120 volt supply. In both cases that guarantees that there will be current flowing on the Grounded Current Carrying Conductor (Neutral). As long as the connections of the Grounded Current Carrying Conductor (Neutral) remain in good condition most of the current from the 120 volt portion of the load will return on the Grounded Current Carrying Conductor (Neutral). If any connection of the Grounded Current Carrying Conductor (Neutral) becomes high resistance for any reason that current will be looking for a way back to the windings of the secondary of the transformer from whence it came that was never intended to carry electrical current. It is nearly inevitable that the leakage pathway will have considerable voltage drop and that the touch potential of some conductive surfaces will become dangerous.
And that's a very detailed explanation of my simple comment in post #21. :D

JAP>
 

kwired

Electron manager
Location
NE Nebraska
So......The HO will not pay for the EC to change the 3 wire in his new "sub panel" to a 4 wire for his range, that has a #6 seu after changing the old service to a meter main.
What is an inspector to do :?
Fail the inspection, it is not compliant with the code the inspection is based on.

What happens next varies from place to place. Some may be like was mentioned and is possibly left as an issue when it comes time to sell the place, others may be required to fix the deficiency within a certain time or other actions will be taken. Some cases it is on the owner, others it is on the contractor to ensure it is fixed.
 
Last edited:
Top