# Very basic question about Phase Loss - internal problem or source problem with Utility Co?

#### Sz NCRC

Joined Mar 2, 2018
1
I just joined AAC in the hopes of benefiting from your collective expertise, given that I have exactly none.
Like many on the east coast, the preschool where I work has been battered by high winds and lost power this morning. Partially. (We closed for the day).
With so many affected by these storms, my outage call is probably low on Pepco's priority list. But I'm trying to figure out how to determine whether my issue is likely to be the result of phase loss from the street, or whether I've got an internal problem. Can anyone advise or offer an opinion?
My water booster pumps and fire suppression system were both single phasing and tripped from overload protections. HVAC systems indicate they are running on "auxiliary power," but are not really heating. Security system is operating, but door automation is down because entire areas (including Von Duprins that control certain doors) are down. Lights and outlets are randomly working or not. Obviously, without sprinkler system, plumbing (toilets!), heat and lots of our lights, we can't have our 160 little ones show up Monday morning. The question is, if it's an external issue with phase loss from the source ... then I will continue to pursue Pepco. But if there's a possibility that the problem is in our Electrical Room at the Main Switchboard or the Pepco Termination Cabinet, or somewhere else in our internal system ... then I need to get busy finding an electrician who can maybe get us sorted over the weekend. I've been assuming it's a Pepco issue with the exterior lines, but if you wise ones suggest otherwise ... I'll head in that direction.
Thanks for tolerating my ignorance and offering any guidance you think might be relevant.
Cheers! Sz

#### ebeowulf17

Joined Aug 12, 2014
3,282
I just joined AAC in the hopes of benefiting from your collective expertise, given that I have exactly none.
Like many on the east coast, the preschool where I work has been battered by high winds and lost power this morning. Partially. (We closed for the day).
With so many affected by these storms, my outage call is probably low on Pepco's priority list. But I'm trying to figure out how to determine whether my issue is likely to be the result of phase loss from the street, or whether I've got an internal problem. Can anyone advise or offer an opinion?
My water booster pumps and fire suppression system were both single phasing and tripped from overload protections. HVAC systems indicate they are running on "auxiliary power," but are not really heating. Security system is operating, but door automation is down because entire areas (including Von Duprins that control certain doors) are down. Lights and outlets are randomly working or not. Obviously, without sprinkler system, plumbing (toilets!), heat and lots of our lights, we can't have our 160 little ones show up Monday morning. The question is, if it's an external issue with phase loss from the source ... then I will continue to pursue Pepco. But if there's a possibility that the problem is in our Electrical Room at the Main Switchboard or the Pepco Termination Cabinet, or somewhere else in our internal system ... then I need to get busy finding an electrician who can maybe get us sorted over the weekend. I've been assuming it's a Pepco issue with the exterior lines, but if you wise ones suggest otherwise ... I'll head in that direction.
Thanks for tolerating my ignorance and offering any guidance you think might be relevant.
Cheers! Sz
I wish I had the knowledge and skills to give you a confident, definitive answer, but I don't.

Having said that, in my experiences in light (ok, very light) industrial settings, I've seen plenty of power outages on numerous kinds of power systems (split phase, 3 phase wye, and high leg delta systems, never anything over 240V though) and never experienced a power loss where one or more phases cut out while others remained. We always lost it all or didn't (in buildings with multiple transformers, I've seen one transformer get knocked out while others had power, but I've never lost individual phases of a single transformer.)

So my gut feeling is that you should get an electrician out there if you can, and start looking for blown fuses, breakers, etc. Just a gut feeling though - hopefully someone more experienced with power transmission will have some insights for you. Whichever way you go, good luck!

#### Ylli

Joined Nov 13, 2015
1,053
It happens. We had half a power outage a few years back, only one side of the 240 vac line was working.

I guess that means that the failure/downed wire is on the consumer side of the distribution transformer. You could cycle your local main breaker, but unless there is evidence of damage inside, I would expect it to be a problem on the outside.

Joined Jan 15, 2015
6,203
Bringing in a competent electrician should tell you, literally within a few minuets if your feeders from Pepco are correct. Should your building not have a phase detector circuit at the point of entry it would be a good and relatively inexpensive investment. This all depends on exactly what the mains are entering the building. Without knowing that it is difficult to suggest any actions you could easily take. The best course of action is notify Pepco and bring in a competent electrician.

Ron

#### joewales44

Joined Oct 8, 2017
150
i had the same symptoms before.
it was broken wire on 1 side of 220 on my side of meter.
i had 110v lights but no 220v heat.
might check with voltmeter at the breaker box.
sometimes it has to have a load for a good test.

Joined Jan 15, 2015
6,203
The question is, if it's an external issue with phase loss from the source ... then I will continue to pursue Pepco. But if there's a possibility that the problem is in our Electrical Room at the Main Switchboard or the Pepco Termination Cabinet, or somewhere else in our internal system ... then I need to get busy finding an electrician who can maybe get us sorted over the weekend. I've been assuming it's a Pepco issue with the exterior lines, but if you wise ones suggest otherwise ... I'll head in that direction.
Let me add a little to my previous post. I have no idea what is coming from PEPCO into your building. I have no idea if your Electrical Room has any transformers or how the incoming power is distributed. With a US Residential system it is easy if one has a voltmeter to check the mains power in from the power company. When we move to industrial buildings or large buildings it becomes another matter.My facility had mains power at entry of three phase 5 KV and the higher 13.3 KV and I would not suggest to someone to grab their handy dandy voltmeter and check for either. Really bad things can happen.

Since the system was working and in lieu of the weather you guys are getting I would guess the problem is with PEPCO but that being just a pure guess.

Ron

#### KeepItSimpleStupid

Joined Mar 4, 2014
5,090
With electronic metering, PEPCO might be able to tell you lost a phase.

It's not a good idea for devices to operate missing a phase and it's wise to shut them down.

In the end, you may find that it's necessary to add 3 phase protection to certain pieces of equipment. That's what we had to do. The building had an ~10 kV feed, 3 phase; broken down to 460 V 3 phase; 208 single and 3 phase, 277 single phase and 120 single phase.

The 460 ran the chillers, heat pumps or basically the building infrastructure. 277 lighting. 208 for smaller stuff like the machine shop motors and pumps for experiments.

You will need to assess what you have to protect in the future. We had compressors and pumps that would cost $5,000 or$10,000 USD to fix, so they were candidates and they were hit. Blowers were hit, but replacing them were comparatively cheap. You also have to look at loss of "production". Your case, the ability to teach and keep the building secure.

I ended up using the Symcom 102A http://www.clrwtr.com/PDF/SymCom/SymCom-Voltage-Monitors-Model-102A.pdf with the adjustable trip and re-start delays. I think we put them on 4 or 5 things.

What can happen (rare) is that the utility can reverse a phase. This can be really bad for pumps.

We were not going to put them on 36 Air to water heat pumps and it wasn't our call for those.
But a $40,000 cryogenic chiller with a$6,000 USD pump, down time and \$1000.00 USD of a rare Freon which knocks out three research systems - yes.