Long residential home runs

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nizak

Senior Member
Got a job where the utility service ended up entering the house at the opposite end of where originally planned.Kitchen, laundry, garage, a/c etc are now at the furthest point away from panel. I am ending up with many circuits reaching 90/120 ft.total length. Voltage drop is maxed on just about every circuit figured. How many here pay attention to V/D when it comes to resi branch circuits? No monies were figured in the job to set a disconnect and run 80' further to the other end of the house. The AHJ has never questioned VD, am I making more out of it than I should? Thanks.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
90 - 120 feet and not much of a run. you will get that in no time.

Did you use the full circuit capacity for your VD calculations? Or the actual load current. Most of the time the load current is much less.

Also what is the source voltage in the morning, afternoon and in the evening? Do you know that info?
 

Carultch

Senior Member
Location
Massachusetts
Got a job where the utility service ended up entering the house at the opposite end of where originally planned.Kitchen, laundry, garage, a/c etc are now at the furthest point away from panel. I am ending up with many circuits reaching 90/120 ft.total length. Voltage drop is maxed on just about every circuit figured. How many here pay attention to V/D when it comes to resi branch circuits? No monies were figured in the job to set a disconnect and run 80' further to the other end of the house. The AHJ has never questioned VD, am I making more out of it than I should? Thanks.
'
Voltage drop isn't as rigid of a rule as anything else. The NEC doesn't actually require you curtail voltage drop to any particular value, although it does contain the recommendations (3% feeder, 3% branch, not more than 5% grand total from point of common coupling to load). "Sensitive equipment" might require a tighter range.

Voltage drop is more fluid of a rule. What do you want it to be? What is your customer willing to pay for? What is most valuable to your customer? It depends a lot on the nature of the loads. Incandescent lighting/heating...who cares? Motors...now we need to be careful.

It also depends on what voltage you start from. Sure you've got a nominal 240 V, but you might start higher than that at your service point. Or lower. It's a moving target. The utilities have a percentage range from nominal in which they must maintain voltage, and you might start low, until they make upgrades to transformers upstream of your place...and then your voltage is high.
 

electricalist

Senior Member
Location
dallas tx
We ran about 200ft from panel to master bedroom only and thought it would be ok
for the general outlets in the room and when the maid plugged in a vacuum cleaner in it tripped.
 
Since you have such a long run...why don't you just run a feeder for a sub panel. That's a lot better than running all those home runs. :happyyes:


Got a job where the utility service ended up entering the house at the opposite end of where originally planned.Kitchen, laundry, garage, a/c etc are now at the furthest point away from panel. I am ending up with many circuits reaching 90/120 ft.total length. Voltage drop is maxed on just about every circuit figured. How many here pay attention to V/D when it comes to resi branch circuits? No monies were figured in the job to set a disconnect and run 80' further to the other end of the house. The AHJ has never questioned VD, am I making more out of it than I should? Thanks.
 

kwired

Electron manager
Location
NE Nebraska
Since you have such a long run...why don't you just run a feeder for a sub panel. That's a lot better than running all those home runs. :happyyes:
Might cost less then all the home runs, especially if you add cost to them because you decided to up size them for voltage drop. Maybe use aluminum feeder instead of a copper feeder.
 

iwire

Moderator
Staff member
Location
Massachusetts
I would not worry about this in the least and unless it saved costs I would not install a subpanel.

These home runs are not long, think about the length of runs in an office building or large store.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I would not worry about this in the least and unless it saved costs I would not install a subpanel.

These home runs are not long, think about the length of runs in an office building or large store.

Yeah but you are not dealing with afci in an office.

IMO, I would , without a doubt, set a sub panel for more reasons than the VD. Afci's do not like the long distances has been my experience. Also the cost of a sub panel would equal the cost of all those runs across the house.
 

kwired

Electron manager
Location
NE Nebraska
I would not worry about this in the least and unless it saved costs I would not install a subpanel.

These home runs are not long, think about the length of runs in an office building or large store.

They are not long runs for an office or large store. They may not be long or a McMansion. 100 foot home runs are long in a typical dwelling and you will use a lot more copper if most of the circuits are feeding loads far from the panel then if you were able to locate the loadcenter closer to where the majority of loads are. And will use even more copper if you decide to upsize for voltage drop. One aluminum feeder across that house to a 100 amp subpanel closer to the kitchen very well may save a lot of $$$ in both material and labor cost. Or it may come out just about even. Something tells me AFCI's will have less problems on shorter branch circuit runs as well, which may save a lot in call backs.
 

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
Maybe I am not understanding this or can not picture it in my mind, but why would an AFCI or other breakers have any issues on VD that is 200 feet away?
 

kwired

Electron manager
Location
NE Nebraska
Maybe I am not understanding this or can not picture it in my mind, but why would an AFCI or other breakers have any issues on VD that is 200 feet away?
VD is only an issue for the load, but excessive conductor length does give you more places to have problems with an AFCI or even "capacitive leakage" on long circuits is sometimes a problem with GFCI protection. I don't know if such capacitive effects would be a problem for AFCI's, but guessing it may be hit and miss just like many other AFCI triggers seem to be.
 

electricalist

Senior Member
Location
dallas tx
After we fixed the tripping problem. The load caused, the boss decided to make it standard practice to set a sub panel at 150' and the builder agreed and framed accordingly on every house after.
Its only my opinion but if you can set the panel allow for adding circuits and sleep well.
 

growler

Senior Member
Location
Atlanta,GA
Got a job where the utility service ended up entering the house at the opposite end of where originally planned.Kitchen, laundry, garage, a/c etc are now at the furthest point away from panel. I am ending up with many circuits reaching 90/120 ft.total length. Voltage drop is maxed on just about every circuit figured. How many here pay attention to V/D when it comes to resi branch circuits? No monies were figured in the job to set a disconnect and run 80' further to the other end of the house. The AHJ has never questioned VD, am I making more out of it than I should? Thanks.

Maybe I am not understanding this or can not picture it in my mind, but why would an AFCI or other breakers have any issues on VD that is 200 feet away?


First off I don't think the OP is taking about 200 ft runs. We are getting carried away here.

The question is about cost and voltage drop. With the kitchen and laundry at the other end of the house and assuming they have a range circuit I can run a 100 amp sub panel to the other end of the basement cheaper than I can run all those long home runs to start with ( add the cost of all that romex for home runs and the range and dryer circuit and it will more than pay for the sub panel and feeder so materials will be cheaper)

Even if we forget about voltage drop and there is a place to add the sub panel it just makes sense to do so.

If the AC is also closer to the other end of the house I would just get a disconnect and run the main panel to the other end of the house. If I can I'm going to set some type of panel near the major loads and in a house that means the kitchen. They should look at the cost of all materials and not just what it will cost to build the service ( and maybe the labor cost also).
 

iwire

Moderator
Staff member
Location
Massachusetts
Yeah but you are not dealing with afci in an office.

IMO, I would , without a doubt, set a sub panel for more reasons than the VD. Afci's do not like the long distances has been my experience. Also the cost of a sub panel would equal the cost of all those runs across the house.

I have not seen one post about long runs tripping GFCIs. As far as costs the runs would have to long to cost more than a sub panel. The larger the wire the more copper per amps carried.
 

ron

Senior Member
'
Voltage drop isn't as rigid of a rule as anything else. The NEC doesn't actually require you curtail voltage drop to any particular value, although it does contain the recommendations (3% feeder, 3% branch, not more than 5% grand total from point of common coupling to load). "Sensitive equipment" might require a tighter range.

Voltage drop is more fluid of a rule. What do you want it to be? What is your customer willing to pay for? What is most valuable to your customer? It depends a lot on the nature of the loads. Incandescent lighting/heating...who cares? Motors...now we need to be careful.

It also depends on what voltage you start from. Sure you've got a nominal 240 V, but you might start higher than that at your service point. Or lower. It's a moving target. The utilities have a percentage range from nominal in which they must maintain voltage, and you might start low, until they make upgrades to transformers upstream of your place...and then your voltage is high.

If your jurisdiction adopted ASHRAE 90.1 as the energy conservation code, or adopted certain ASHRAE 90.1 sections into their version of an energy code, then the voltage drop limitations found in there are a code, and not a recommendation.
 

ron

Senior Member
As far as costs the runs would have to long to cost more than a sub panel. The larger the wire the more copper per amps carried.

I agree voltage drop isnt much of an issue, but I think labor and material could depend a lot on the layout. 90 amp Aluminum SER is a dime a dozen, where many of the branch circuits would be copper. If one is in the habit of running NM for a range, thats big chunk of change to get to the other end of the house. As others have said, is there an AC? Where is the water heater (if electric)? Then there is the luxury of the main panel having less stuff in it, easier to make up and neater, maybe now a 30 space instead of a 40 space....? Another consideration may be number of holes to drill. There is the bundling/insulation thing depending on the situation and interpretation, so maybe you need a bunch of 1 1/4 holes for all the branch circuits vs less if many go to a sub......
 
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