Electrical Engineering/Transformer sizing question

[mcsquared]

This is kind of a random problem I am having but I am at the end of my googling abilities. So any help would be appreciated.

My father and I own and Industrial "Condo" which is governed by a POA. We bought it as a father-son tinkering space. He did his retirement thing and I had my woodworking shop in there. We split the place with a metal artist for awhile to pay the bills. It has a 100 amp panel in the unit which isn't much, but suited our needs. It is a complex with 10 units each metered separately. There were a couple of auto repair businesses, auto body guys, a couple contractors and one rich doctor who stored his classic car collection in a unit. Each unit had a 100 amp panel except one unit has a 200 amp. So a total of 1100 amps sharing a single transformer originally.

Fast forward a couple years and 7 of the 10 units are now being used by MMJ growers, who use a shit load of electricity. Most of those guys upgraded their panels to 300-400 amps. So now the transformer on the pole is on its last legs, there is some type of oil dripping from it and everybody is afraid that it is going to blow. So the MMJ guys are trying to spearhead an effort through the POA to get a new upgraded transformer. The sticking point is that they want to spread the expense across all 10 units. They are talking a price range of $50-80k for the upgrade. So obviously, I don't want to pay anything and think they should pay because they are the ones who need the power.

Their claim, which I am hoping to disprove, is that the transformer was undersized to begin with. And therefore, an upgrade was necessary before they all upgraded their units. There is a 700 kVA transformer (I think that is the right terminology, does that make sense?) on the pole currently. And based on what I have found on the googles this is plenty big to feed the original configuration.

My second question is about the oil that is leaking from the transformer? I read somewhere that this stuff is pretty nasty stuff and will require some kind of environmental remediation to clean up. Is this true?

[coreshot-tourettes]

This is kind of a random problem I am having but I am at the end of my googling abilities. So any help would be appreciated.

My father and I own and Industrial "Condo" which is governed by a POA. We bought it as a father-son tinkering space. He did his retirement thing and I had my woodworking shop in there. We split the place with a metal artist for awhile to pay the bills. It has a 100 amp panel in the unit which isn't much, but suited our needs. It is a complex with 10 units each metered separately. There were a couple of auto repair businesses, auto body guys, a couple contractors and one rich doctor who stored his classic car collection in a unit. Each unit had a 100 amp panel except one unit has a 200 amp. So a total of 1100 amps sharing a single transformer originally.

Fast forward a couple years and 7 of the 10 units are now being used by MMJ growers, who use a shit load of electricity. Most of those guys upgraded their panels to 300-400 amps. So now the transformer on the pole is on its last legs, there is some type of oil dripping from it and everybody is afraid that it is going to blow. So the MMJ guys are trying to spearhead an effort through the POA to get a new upgraded transformer. The sticking point is that they want to spread the expense across all 10 units. They are talking a price range of $50-80k for the upgrade. So obviously, I don't want to pay anything and think they should pay because they are the ones who need the power.

Their claim, which I am hoping to disprove, is that the transformer was undersized to begin with. And therefore, an upgrade was necessary before they all upgraded their units. There is a 700 kVA transformer (I think that is the right terminology, does that make sense?) on the pole currently. And based on what I have found on the googles this is plenty big to feed the original configuration.

My second question is about the oil that is leaking from the transformer? I read somewhere that this stuff is pretty nasty stuff and will require some kind of environmental remediation to clean up. Is this true?

A picture would help. Would allow one to see pole config and xfrmr type.

If the transformer is leaking oil at the top you may be ok for awhile as it's boiling off (which is still bad but it's just vapor recondensing, there's not a lot of loss). If it is leaking from the bottom then you have a problem as the oil is necessary for cooling. No cooling = overheat = flashover = whumpf and big-ass fire.

700kVA is correct terminology, but that is a fuckton of power even with 1100A at the panels. The xfrmr is not undersized even with the new configuration, something else is wrong.

Normally I'd say that if they are running fluorescent bulbs as the majority of their load, that may be part of the problem. FL bulbs have a power factor of 0.5ish which means that there's twice as much current needed to dump the same power into the bulb. But even if they have a PF worse than the worst bulb on the market of 0.3, the xfrmr would still be adequate for that load.

You might just have had some corrosion that is causing the xfrmr to leak, or maybe a lightning strike fried a winding and is causing the other 2 to take more power...

Actually, that might be it.

In fact, you could have had a winding or two open for years and never seen it until these guys moved in due to how oversized the xfrmr is.

Transformer oil is not terrible environmentally. Here's a typical MSDS. Check local laws.

So, basically, I can theorize a possible scenario that would lead to a leaking xfrmr even with it being oversized.

(Your power company may tell you your power factor. They usually get cranky if your PF drops below 0.9 as you are making them take additional losses, check your bill)

Standard disclaimer: This is a theory based on limited information and may be wrong. Transformer fires are no fucking joke and you may be really really close to one. Call a licensed electrician.

[mcsquared]

That's a bunch of good information. I knew it wasn't all dentists here.

I believe coolant is boiling over the top like you describe. It isn't enough to see, but enough that you wouldn't want to stand underneath it.

Now you got me thinking that I might be confusing the 700kVA with what they want to put in, not what it currently is. I'll try to see if i can get a picture.

So from your response it is my understanding that any transformer above 460kVA would have been adequate for the 1100amps unless there is something else funky going on?

[DJSapp]

From my experience setting up new offices and getting power drops is that everything on the utilities side of the meter is their issue and you shouldn't be paying very much for it (closer to 10k than 80k). You'll pay the rest over the long haul with the power bill. Typically trading a pole mounted can out for a larger one is a really easy thing for a major utility provider to do. Just call up your local utility and ask for their engineering division and you'll get the scoop. They'll provide estimates and everything, just explain what you need.

The other issue may be further down the line that the utility may not have the capacity on the O/H line for the additional load. Running a whole new service out there or upgrading multiple cans is a bigger issue. And if the MMJ guys have already upgraded and are working just fine, why do they want a bigger xfmr? More expansion?

And everything coreshot said about the leaky oil. If it is coming from the top, and if it has been a dry, dusty summer, be careful when the first rain comes. If there is a leak at the top, a small rain can cause enough of the dust to get into the xfmr and cause it to blow. This happened in my hometown every fall after 6 months of no rain.

[coreshot-tourettes]

So from your response it is my understanding that any transformer above 460kVA would have been adequate for the 1100amps unless there is something else funky going on?

Yes, but leave out the 460kVA for now, I deleted it as I was assuming all 120VAC service which may not be true for all your units.

Also deleted that part as I was not clear whether the load was 1100A or the panel breakers total to 1100A but the load was less. If the load is 1100A then power factor applies. If the panels themselves are 1100A then it does not.

I'm a little confused why they would want to put in a 700kVA xfrmr if that's the case, that seems really really big for your application.

Again, talk to licensed electrician kaboom electrocution death blah blah blah.

[mcsquared]

XCEL, licensed electricians, engineers (all hired by the growers, yet they seem to think I should pay them back for our share) have all been on scene. I understand that I am giving you half-assed information and don't intend to go sticking my finger in a light socket based on your recommendations. I am just trying to understand what is going on and mainly how hard I should fight paying for any of this.

In the original configuration the panel breakers totalled to 1100 amps. Not sure what the actual load is as the MMJ guys are using as much as they can and the other guys are using minimal amounts.

Apparently, XCEL will provide the transformer, we are responsible for the pad, running the underground wires to the building, all the code requirements that go along with doing that. There is a cinderblock wall to build, bollards to install, etc.

Oh yea, and thanks for the information. It helped me at least figure out intelligent questions to ask. I appreciate it.

[DJSapp]

Yes, but leave out the 460kVA for now, I deleted it as I was assuming all 120VAC service which may not be true for all your units.

Also deleted that part as I was not clear whether the load was 1100A or the panel breakers total to 1100A but the load was less. If the load is 1100A then power factor applies. If the panels themselves are 1100A then it does not.

I'm a little confused why they would want to put in a 700kVA xfrmr if that's the case, that seems really really big for your application.

Again, talk to licensed electrician kaboom electrocution death blah blah blah.

Original load = 9 units @ 100 amps + 1 @ 200 = 1100 amps

New load
7 units @ 300-400 amps and 3 units @ 100-200 amps = 2400-3400 amps.

700 kVA may not be enough if they're running 240 or 460 on the 300-400 panels.

[NmbrdDays]

In no way do I work for a power co. I'm just a union electrician. There are some simple formulas you can use to get yourself into the ball park of what you need. P=IV. You may want to talk to an elec engineer to give you the actual numbers. As for installing them and taking them down. That's a diff story. The oil is some nasty shit. Def don't get it on you. It's worse than hydraulic oil. Be spilt some before when one fell off the pole. We didn't worry about it but I don't think it's good for mother earth.

[coreshot-tourettes]

700 kVA may not be enough if they're running 240 or 460 on the 300-400 panels.

Yes, this. It wasn't clear what the voltage was on the upgraded panels so I removed my calculations.

[DJSapp]

Apparently, XCEL will provide the transformer, we are responsible for the pad, running the underground wires to the building, all the code requirements that go along with doing that. There is a cinderblock wall to build, bollards to install, etc.

Oh yea, and thanks for the information. It helped me at least figure out intelligent questions to ask. I appreciate it.

Now we're getting to it. Pad + new conduits & cable + cmu wall & bollards + new skid mounted xfmr... I can see 30-40k easily from here. Those boys did their homework. Better read up on your POA agreement. I would think that you'd have an argument that the TI's for the panel upgrades were their own doing, and the original condition that they moved into was sufficient for the space leased/purchased. Hell, if XCEL upgraded the drops to each panel, they (should have) did their homework and determined that the existing transformer would handle it. Therefore any further expansion is at their sole request and is their issue to handle.

Are you the owner of the entire complex, or just your unit? If you own the whole thing you could just evict them instead. The feds are cracking down on the owners of MMJ storefronts, the grow ops aren't too far behind. Just sayin...

[mcsquared]

Now we're getting to it. Pad + new conduits & cable + cmu wall & bollards + new skid mounted xfmr... I can see 30-40k easily from here. Those boys did their homework. Better read up on your POA agreement. I would think that you'd have an argument that the TI's for the panel upgrades were their own doing, and the original condition that they moved into was sufficient for the space leased/purchased. Hell, if XCEL upgraded the drops to each panel, they (should have) did their homework and determined that the existing transformer would handle it. Therefore any further expansion is at their sole request and is their issue to handle.

Are you the owner of the entire complex, or just your unit? If you own the whole thing you could just evict them instead. The feds are cracking down on the owners of MMJ storefronts, the grow ops aren't too far behind. Just sayin...

We only one one unit, all the other units are Owner Occupied as well. The argument that I am trying to make is that they bought the units with a certain capacity, and the transformer was sufficient for that use. If they require more power, the onus is on them to upgrade the entire system, not just their units and then get us to pony up for the transformer. And furthermore(!!!!!) by upgrading their units without consulting the POA as a whole, they put the entire system under stress and are putting the rest of the units at risk.

Unfortunately, the POA agreement is pretty vague in this regard. And with various MMJ growers owning 7/10 units they basically have the majority they need to get the POA as a whole on the hook. Their main argument is that the transformer was undersized all along and that for every unit to be able to use their allotted amount of power we would be doing this anyways, and since Xcel is supplying the transformer, we might as well go hudge.

[Stowelen]

Talk to an EE because services are not sized by adding up all the panels main breakers. The national Electric Code has a formula for services. No way in the original service you would have to be at 1100 amps. I do apartment buildings and commercial condos all the time and use the code to size services. I think these guys are trying to get you to pay for their needed upgrade. They are tripling the size of their services, no way original xfmr was sized to carry that load. Just my opinion, good luck.

[slim]

Call the Feds.

[DJSapp]

Their main argument is that the transformer was undersized all along and that for every unit to be able to use their allotted amount of power we would be doing this anyways, and since Xcel is supplying the transformer, we might as well go hudge.

That will never hold up in court. Unless the MMJ growers replaced the panels w/o the knowledge of XCEL (i.e. installed without permits which would be against the POA and a slam dunk), XCEL would have had to verify that the xfmr had the capacity to handle it. If all the MMJ people are concerned about is a transformer that looks like it needs replacement, that's XCEL's issue, not theirs.

[andynuts]

Sorry for the long time reader/lurker non poster response....


First basic math on this, using 1000A as a round number.

If you have a 208V/3 phase service. 1000A*208v*1.73 (square root of 3) = 360KVA.

If you have a 480V/3 phase service. 1000*208V*1.73 = 831KVA.

700KVA at 208V/3P = 1944A.

Do they want to increase the service to the building because it is really maxed out, or do they just think it is? If I were you this is what I would do first as an engineer.

1. How big is the building, total square feet give or take?

2. What voltage is the service? What does your main 100A panel say? Are there other transformers in the building?

3. Go look and find our what size the service is to the building. This would be the main panel or switchboard, if not maybe its a big gutter with meters above it, can you see how many and what size conduits come out of the ground into the building? Is it 1000A, 208V/3P? Maybe you can see the size an number of conduits going down the pole into the ground?

4. Get a hold of a utility contact to find out what the building is currently using. What is the peak load? You can usually just call them with your address and get a local rep to talk to. Sometimes they want you to fill out an application before they give you a name, but give it a shot and call them. The actual demand is usually a lot less than you think.

If an engineer sizes the service its based on a calculated load on the building (National Electrical Code), not adding up all the panels, usually with some growing room built in. When a developer or electrician does it it (they did't need a PE stamp for permit) they might just add up the panels to size it, or they might just wing it based on prior jobs. Either way when you build a building you tell the utility what size service you want or are going to install. The size of your service is really the size of the feeders from their transformer secondary to your building. If you have 11 sub panels in the building then there is a probably a main switchboard. Find our what size this is and what voltage it is. Its probably 208V/3 phase since it sounds like light industrial.

The Utility on the other hand usually does not have to abide by the electrical code, they install whatever size transformer they think you need based on real demand experience. So if you install a 1000A service (360KVA) they might only install a 150KVA transformer because they are the ones who buy and own the transformer, that's why it isn't yours to maintain. They make money off the power bills, the more you use the more they make so they give you a bigger transformer.

If some tenants changed from 100A to 300A and you all have separate meters then the utility would have know about it because those are different size meters sockets, unless they made those changes without getting a permit or telling the utility.

So its possible that your service is fine, but the utility needs to up-size their transformer because nobody ever told them that the load was going up in the building. Before you get roped into paying for their upgrades make sure that they are warranted. 700KVA is pretty big.

[bongora3]

<----EE with some NEC knowledge

This sounds very suspect.

A) If the transformer is leaking be careful. The toxicity depends on how old the transformer is. Older units (pre 80's) used PCB's (which form furan gas.....really bad stuff). Newer transformers use mineral or silicon based fluid.....(much safer). This is 100% the utilities responsibility to fix.

B) Don't let the MMG's sucker you into laying out any $$$. If the current utilities were not sufficient for there needs, then any upgrade cost should be covered w/o effecting your service.

And FYI:
The sizing of the service is determined by the utility, the rest is determine by a hired EE (who hopefully has a PE or access to someone with one). Most of the time the contractor just goes by previous projects...and just seeks approval later.

[Tye 1on]

Sorry for the long time reader/lurker non poster response....

perhaps the most informative/helpful first post ever.

[andynuts]

Ya weird first post since I've read a billion ski threads on here. But I'm a PE and do this for a living so figured might as well chime in.

Ya the Utility owns the transformer, its theirs to fix not yours.

The utility should have a service letter on file that says exactly what they agreed to provide the building. The original developer had it but probably lost it.

The MMJ guys are high if they think you should help pay so they can make more money. If they want more capacity they should pay for it, otherwise they have to live with what they have.

[auvgeek]

perhaps the most informative/helpful first post ever.

+1. Good on you for providing helpful info within your area of expertise. One of the main reasons I love TGR.

[mcsquared]

For real, thanks a lot for all the information. I got enough to ask some real pointed questions. I'll be sure to let you know how it turns out. And yes, they are totally high.