PSE

Open Neutral

Senior Member
Another one of my off-base requests.

I'm been tasked to reach someone clueful on expansion issues at a residential Puget Sound Energy customer's site. (Albeit a bigger user than most one: the bill I'm looking at is for 7800 KWH.)

The folks on-site there have not been able to get past the customer service firewall to someone with actual clue. (This sounds a lot like PEPCO here...) I looked for something like PG&E's Greenbook but have not found anything.

I need the person I'd get if I could say "shibboleet" (re: XKCD])

A PM is fine if you want.
 

junkhound

Senior Member
Folks who are personal friends are all retired from PSE so have no inside source, but,

Surprised you cannot find what you need on PSE website, but they have revised part of the site recently.

Had no problem 6 years ago adding another 200A service to a customer's house (much easier than upgrade and long feeders) PSE pulled the 175 ft of 4/0 service (my trench) low flat fee, forget what it was then.

If your 7000 kW-hr resisdence is multi-family, lots of grnts for energy efficient goodies (gets tacked onto everybody else's bill here). I got a new HPWH for own house for just the sales tax.

What is involved in 'expansion'? A new wing on apt building? 7000+ kw-hr implies a 5 unit apt building.. PSE installed just a single 37 kW distribution transformer for the last HFH 5 unit building (electric kitchen but gas heat) I helped .
 

Open Neutral

Senior Member
Thanks for the response.

You could say multifamily:

4 humans
3 dogs
2 cats
12+ koi in 20,000 gal pond
2 plug in electric cars
2 GSHP's
1 Endless pool.

Expansions include those last three line items, but also gridtie solar. Did I mention the machine shop?

We can trench the 300 ft route [1] but the last 15 ft go under the house somehow. Guess 811 will know where.

Don't want to jinx myself, but gave up on main part of web page and found a map listing various PSE projects. Chose the one closest and bingo - name and phone of project boss. Called him, he answered, we talked, I sent him all the data. Have not heard back yet but it's hopeful.

I'm in the DC area trying to avoid getting run over by an Abrams, but will be on-site there on Friday. I found imagery of the new meter expansion:
https://photos.app.goo.gl/UsznernB1wwDhZkU7
with CT's but can't tell enough from it.


1] I worked on his last house build; 1400 ft of 4" for PG&E, some of it getting winched up a slope too steep for the Ditch Witch.
 

StarCat

Senior Member
Another one of my off-base requests.

I'm been tasked to reach someone clueful on expansion issues at a residential Puget Sound Energy customer's site. (Albeit a bigger user than most one: the bill I'm looking at is for 7800 KWH.)

The folks on-site there have not been able to get past the customer service firewall to someone with actual clue. (This sounds a lot like PEPCO here...) I looked for something like PG&E's Greenbook but have not found anything.

I need the person I'd get if I could say "shibboleet" (re: XKCD])

A PM is fine if you want.
I like your use of the word Firewall but I would go more extreme if not for want to remain moderate in a public venue....

Is it not interesting and also very telling that so many persons sit behind telephones, and computer consoles in large office buildings, AND
Draw a paycheck
Do not get anything useful done
Obstruct things
Do not have the slighest idea whats really going on in the real world
And so forth.
The exact same kind of compartmentalization mentality seemingly raining down from above is what creates all the useless technology that " does not perform " and that so many have taken as normal somhow. I am speaking about the devices and gadgets that waste tons of your time every day, that did not formerly exist and that we could for sure do without.
Its a sign of the times. If Tradesmen got on the same page, and were truthful about things and started saying no En Masse, things could start to change.

Star
 

Open Neutral

Senior Member
Update:
Like most firewalls, it's soft on the inside.

Found a name, who referred us to the Tacoma construction office, and after the GC visited there yesterday, today a lineman stopped by.

We have 360+ ft of 350MCM from a 37.5KVA oil cooled pad xfmr feeding into the CT box.
It runs under the garage, it appears, TBD.
I would have assumed something bigger than that but...

If necessary, we discussed paralleling with another run, or extending the HV and putting a transformer at the house.
 

Open Neutral

Senior Member
Here's the update on my PSE saga.

After the lineman visit, 10 days later got Metering to come look in the CT compartment. We have 200A CT's.
Then I got a Project Coordinator assigned. He visited the site and we soon locked on the big issue.

The house is {roughly} Z shaped. The * is the CT-fed meter; inside that wall is the CT case.

811 confirms the route from the case, from under the house's inside corner and then SE as shown by the diagonal marks. The PC said current PSE standards would not allow that. Plus, that inside corner is now covered by a deck.

The line to the transformer may be direct burial past the elbow, or in DB120 conduit; we donno yet.

We clearly need to replace the existing 350MCM with 700+MCM cable. How is the issue.

If the 3" sweep elbow continues from the CT case in conduit to the porch edge, we could trench from the transformer to the porch edge, and PSE could pull in 700+MCM. But that's a big IF.

The upper leg of the Z has crawl space beneath it but PSE won't allow a route right under it.

I'm not anxious to go digging for the 240v feeder not knowing if it's in conduit or directly buried. Our current {err} plan is to have PSE pull power at transformer, open their meter cabinet and we'll slide a fiberglass snake down the conduit to see how far it goes. If there's an hope of reaching the end, we'll dig/drill each side of the marked route then carefully join the holes to expose the line.

Plan B is a bore from the meter, under the crawl space and deck into the yard.

Plan C is to abandon the existing route, go straight north from the meter location, bore under a driveway, & have PSE place a new pad-mount xfmr there. Dig a 18" by 48" trench 300 ft from it west to that road's primary run.

Did I mention the septic field we're avoiding?
 

Attachments

Open Neutral

Senior Member
So I've been through many hoops.

Looks like it's Plan C for this. It will involve a 550 ft long 2" boring job, if PSE will extend from the last existing transformer. They're not yet sure.

I'm calling around seeking boring companies interested. (Found one NOT, they are busy with a 3000' long, 19' diameter one. Gulp.)

One question for the brain trust here. The PSE handbook shows terminals as seen below. I've searched under many nouns to no avail; where might I find them?



 

PaulMmn

Senior Member
I always enjoy driving past a place on the highway where they're drilling under the road.
Signs warn you about the upcoming activity, and when you're past it, the sign reads

. LEAVING BORING AREA
 

gar

Senior Member
190822-2235 EDT

Interesting transformer size.

By comparision I have a 50 kVA pole transformer. This supplies two street lights, my next door neighbor, and me. My average consumption is about 1.5 kW, seldom do I hit a peak of 6 kW. My neighbor is probably about the same.

Low source impedance at the transformer, but wimpy wires from it.

.
 

Open Neutral

Senior Member
So we {finally} got the plan back from PSE for a dedicated transformer installation. What surprises me is they have spec'd a 100KVA transformer when the house is presently fed by a 37.5 KVA shared with another house.

I'd asked a PE there and based on a peak month of 8900 KWH, & was told 29KW estimated demand.

They do show a LRC of 134A but would that be THAT large a factor?
 

Open Neutral

Senior Member
Well, the new EC [the third, alas....] has raised a major alarm. Given the dedicated 100KVA transformer PSE has spec'ed, the AIC is so large the existing four panel boards would have to be ripped out and replaced.

This is an area I know almost nil about. Would all breakers in the house have to meet a higher AIC rating, or if there is a new Main that does, is that sufficient protection?

(The EC has a on-site meeting scheduled to ask the PoCo why they spec'ed that transformer so it may be moot.)
 

GoldDigger

Moderator
Staff member
Well, the new EC [the third, alas....] has raised a major alarm. Given the dedicated 100KVA transformer PSE has spec'ed, the AIC is so large the existing four panel boards would have to be ripped out and replaced.

This is an area I know almost nil about. Would all breakers in the house have to meet a higher AIC rating, or if there is a new Main that does, is that sufficient protection?

(The EC has a on-site meeting scheduled to ask the PoCo why they spec'ed that transformer so it may be moot.)
If the main and all of the feeder and branch breakers are from the same manufacturer it is possible to get a "series rating" document from them that certain combinations of high AIC main and lower AIC downstream breakers have been tested in specific combinations to survive a downstream bolted fault. When you have to series rate 3 levels instead of two it gets more complicated
 

charlie b

Moderator
Staff member
Given the dedicated 100KVA transformer PSE has spec'ed, the AIC is so large the existing four panel boards would have to be ripped out and replaced.
What has led you to believe that that AIC is large? Perhaps I missed it, but I didn't see what the facility has for a voltage and phase configuration. If, for example, it is 120/240V single phase, then the fault current at the transformer secondary terminals would be around 7000 amps. That is not a "large" number, and it would be smaller after passing through the secondary conductors. If you have 120/208V three phase, the AIC will be lower still.
 

charlie b

Moderator
Staff member
A good rule of thumb is that the available fault current at the secondary terminals of a transformer can be estimated by taking the full load current of the secondary side and dividing by the "per unit" impedance of the secondary windings. That later value is often on the order of 5.75%, so the value you divide by is 0.0575. Different transformers will have different values. In the example I gave earlier, the full load current for a 120/240V single phase 100 KVA transformer is 100,000/240, or 417 amps. Dividing that by 0.0575 give an AIC of 7,246 amps.

Most panels have a minimum AIC of 10,000 amps. To get that from the transformer, it would need to have an impedance of 4.17% or lower. It is possible that the utility transformer's impedance could be lower than that. Even still, the impedance of the secondary conductors will significantly reduce the available fault current at the building's main breaker.

So don't take the EC's statement at face value. Ask for the exact number that PSE provided to him (or her). Then you can do a calculation of the impact of the secondary conductor's impedance on the value PSE gives you. I am willing to predict that the final result is below 10,000 amps, and that you therefore do not have a problem in need of a solution.
 

Open Neutral

Senior Member
Thank you.
We do have a substantial secondary connection - dual 350MCM of about 80 ft in length.
But I will find out the exact details.

And a side question: Does Washington State L&I require a PE signoff on utility designs?
After the Merrimack Valley Gas disaster, the NTSB came out swinging against utility exemptions to the PE requirement.
 
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