Service drop amps

[paulmars]

I need to know how many amps my service can supply. Im not confident that my main breakers reflect that.

Ive asked the power company several times. They wont tell me.

Id rather not hire another electrician (yet).

Tks,
Paul

 

[Snoonyb]

Are you asking the capability of your service entrance panel, because that is on a label, there-in, and is stated as a limit for the buss bars installed.

If you are asking the capability of the provider, to supply you, walk in and tell them that you a planning a service upgrade and can they service you?

You'll likely be referred to your local building authority, who will likely refer you to the yellow pages, and suggest you ask a local electrician, who may take the time to enlighten you about the power providers general standards, in your area.

 

[bud16415]

I once had an old house that had a 60a fuse panel. I had the power company out for something and I asked the guy doing the work what they would do with the feed to the house if I upgraded to a 100a breaker panel and he said nothing it was large enough. I asked how about 200a and got the same answer. So as far as I know the line from the pole to the house is or could be well overrated.

 

[Snoonyb]

I once had an old house that had a 60a fuse panel. I had the power company out for something and I asked the guy doing the work what they would do with the feed to the house if I upgraded to a 100a breaker panel and he said nothing it was large enough. I asked how about 200a and got the same answer. So as far as I know the line from the pole to the house is or could be well overrated.

Interestingly, a lot of the high voltage lines are #10 copper, while the 100A service drops are #4, 19 strand copper.

 

[JoeD]

Your sevice can supply up the value of your main breaker.

 

[paulmars]

"Your sevice can supply up the value of your main breaker."

even if the service drop is rated for less. that's good to know.

 

[ajaynejr]

Assume that your service will supply amperage or watts up to the rating of your main (first whole house) breaker set. No need to ask.

If you are increasing your houehold amperage, when you pull the permit for the new panel with the greater amperage main breaker, include the power company among the entities to notify so they can put this on file and/or inspect it. This is a declaration, not a request (or imperative or exclamation).

Appliances, electronics, tools, etc. do not (and cannot) limit the amount of current (amps) they draw for the benefit of a generator or power supplier, unless they have built in electronic circuitry expressly to limit the current draw. All that can be done is have overcurrent protection (breakers, etc.) to shut off the power when excessive amounts are drawn. Some EV car chargers contain such circuitry with a user setting for the desired maximum amperage.

 

[PJB12]

Be sure to tell the electric utility's planning department, in writing if possible, when you do a service upgrade. Have a permit and the work inspected by the AHJ.

In any state or province where I'm licensed and have worked, the drop from the pole to the attachment point is the utility company's property & responsibility. Some go farther to even include all the way to the load center's main disconnecting means.
If your load is larger than the drop can handle and the drop burns, the electric utility will fix it.
(And you are inconvenienced and have a pair of live conductors laying on the ground.)



My house has 150 amp single phase disconnecting means. The service drop conductors are little #10 copper conductors. The utility was made aware before I upgraded. The service planner brat said: "Call when it burns."

They have not burned for a few reasons:
Even though the service's overcurrent protection is 150 amps, it wold be quite rare if someone actually had a 150 amp load on a phase.
Wires in free air can take a whole lot more current than those in a conduit or with an outer covering, as evidenced by our
#10's surviving.
Harmonics are low in our house, thus there's less heat on the messenger wire.

The advantage if it fails is that we will get larger conductors (probably #4 triplex) and some milisecond lamp dimming when the air conditoner starts might stop. Might.

The power company follows a different set of rules than electricians follow. An example is Detroit Edison DTE Energy). They follow the Green Book and electricians follow NFPA 70, or the local code. Electric utilities can do some crazy stuff that electricians are not allowed. (I've worked for both sides of that coin.)

Paul

 

[ajaynejr]

I find it hard to believe that the power company could use ten gauge overhead power lines. There is wind and snow load that puts physical stress on the wires.

 

[PJB12]

From Ahaynejr "I find it hard to believe that the power company could use ten gauge..."

Yup, it's ten gauge. I can't imagine the harmonic unbalance stress it puts on their transformer when I have a heavy, non-linear 120 volt load running. Not my circus, Not my monkey.

The messenger is type CCSR, so it's got some strength. CCSR is like modern type ACSR, but copper instead of aluminum.

The messenger works quite hard due to branches in Detroit Edison's easement smashing into it They don't care and I can't reach. In an ice storm, it can droop mid-span several feet.

Hopefully when it does fall, it will "break" mid span so they have to run new cable.
"Golly, Mister Lineman, I didn't see the cable laying on the ground when I ran my lawn mower over it ten times." (After de-hotting it at the pole, of course)

Paul
PS: If the #10 drop seems crazy...
When I bought the house, the un-fused service went through the wall, into the kitchen. Then it went into an open bus meter socket, then to an open double pole knife switch on the wall. The load side of the switch had bus strips with screw terminals for the branch circuits (still not fused, still open bus).

The switch had an official looking sign next to it: "Danger Do Not Touch". Guess that sign made it all safe.