Voltage drop for service conductors?
- Thread starter cppoly
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Carultch
Senior Member
- Location
- Massachusetts
NEC recommends no more than 3% on either feeder or branch, and not more than 5% total. Service conductors are not covered in this recommendation. If it were my design to defend, I would blend it in with the constraint on voltage drop for the feeders, such that feeders + service conductors do not exceed 3%.
Voltage drop is not a hard rule. It is a "soft rule" that it is not enforceable under the scope of the NEC, for general applications. Energy efficiency codes might enforce it, and it may be a safety issue if you have voltage sensitive equipment.
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- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
The OP mentions service conductors.
I think we can assume that this is a reference to the conductors which are not yet OCPD protected but are downstream of the service point. Those are indeed under the control of the customer. That makes it logical to include with the feeder drop.
Conductors upstream of the service point are under the exclusive control of POCO, and might have a 5% drop all on their own and still allow POCO to meet their voltage delivery commitments.
The NEC language referring to feeders and branch circuits avoids the chance of being misinterpreted to include POCO conductors.
I see a lot of 4/0 URD aluminum used for 240v 200 amp 1ph services coming from the utility pole to the line side of the meter on the house, mostly out of habit.
I would think when the utility pole is located 100 ft or so from the house, then another 35 or 40' up the pole to reach the Transformer one should probably start considering upsizing the wire for voltage drop although I hardly ever see that happen.
JAP>
I would think when the utility pole is located 100 ft or so from the house, then another 35 or 40' up the pole to reach the Transformer one should probably start considering upsizing the wire for voltage drop although I hardly ever see that happen.
JAP>
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
I believe most POCO adhere to the ANSI C84.1 standard at the point of use (i.e. the service disconnecting means?; example).
No.
The customer provides the wire from the pot on the pole to the line side of the meter base.
JAP>
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
That varies from POCO to POCO.
In many cases the customer provided wiring extends only as far back as the weatherhead for an overhead drop.
Underground also varies, with the customer sometimes providing only the raceway to the base of the pole and POCO pulling their choice of conductors.
In the case I'm in any way.
The customer wanted to build a shed in his back yard but the overhead service was too close to where the roof would be so when he had to move it he was left with the option for a pedestal by the existing utility pole for $500.00 and he come from that or leave the meter on the house and install a new underground and provide the wire
to the utility pole to take the place of the overhead that would be taken down.
JAP>
The customer wanted to build a shed in his back yard but the overhead service was too close to where the roof would be so when he had to move it he was left with the option for a pedestal by the existing utility pole for $500.00 and he come from that or leave the meter on the house and install a new underground and provide the wire
to the utility pole to take the place of the overhead that would be taken down.
JAP>
- Location
- Massachusetts
- Occupation
- Licensed Electrician
- Location
- Massachusetts
I agree, do the NEC service calculations and you are already oversized but beyond that when the calculations come out to say 150 amps or 125 amps or even as little as 90 amps guys will roll up to 200 amp service 'just in case'.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
That's the way it is here: 10 feet of conduit on the pole and enough wire to get to the pot. Utility puts u-guard the rest of the way. So in your area for underground, utility aways provides wire to meter? I assume you have to provide conduit then per their specs?
- Location
- Massachusetts
When I see 'from pot to the line side of the meter base' I assume overhead lines.
Apparently jap was specifically talking underground while the OP did not specify.
peter d
Senior Member
- Location
- New England
National Grid requires the customer to supply and install the wire and conduit for an underground service.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Sounds like some different Jargon going on. Here in central NY, everyone uses "underground" to refer to a service that is overhead lines, down a pole, underground to meter and service equipment. I have heard some people in other places call that "overhead to underground". People in more populated areas probably think of "underground" as being a situation where the utility conductors are also underground and the connection is in a vault. I would call that a URD setup. I have also worked in the city of Seattle for years, and now that I think about it, "overhead to underground" is pretty rare there, cant say I have ever done one there. Mostly overhead or URD.
- Location
- Massachusetts
For sure local differences
I call them what the NEC calls them even though the NEC does not apply to them in many instances
In that case though you are not doing the overhead at all are you? The overhead would be the utility and 98% of your work is the underground portion save for a riser at the pole and meter right?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
You bring up an interesting question. So what are the conductors on the pole? They dont seem to fit either of those definitions. I admit I dont actually know where the service point is on these setups, but I think it is further back than the line side of the meter. The reason I assume that is the utilities dont have any specific requirements for the conduit/wire/trench from the meter to the pole, I provide and install it, and they never inspect it. Maybe the service point is the top of that 10 foot stick of schedule 80 I install on the pole, at which point it changes to U-guard? Or we could just say there are neither overhead nor underground service conductors?
Let's just say they are both. :happyyes:
Really, though. There is nothing in the NEC which says they must be one or the other for the entire run. You have one portion which are overhead and one portion which are underground. According to recent editions of Code, where the Service Point is located only changes what each portion is called, Service Drop vs. Overhead Service Conductors or Service Lateral vs. Underground Service Conductors.
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