Straight 480 service

Does anyone know of a foolproof way of testing the metering on a 480 straight service before it is re-nergized? I closed an underground one in after finding 2 of the 3 bayonets blown a month or so ago and just about the time the door hit the padmount when I was shutting it the meter socket exploded (probably a 5 sec time frame)! A meter service tech said I could have them test the socket 1st next time but another tech said he only knew of testing continuity on the vts and it wasn't a grantee?

I looked the socket over before closing and didn't see anything but never again? The dam socket was just above the top of the transformer facing me about 5 - 10' away. I got lucky that the meter didn't shoot out (it wasn't a bolt on meter either!) at my face and the socket cover actually got hung up on the locking tab and meter socket seal so most of the crap went over my big @ss head!

Thanks

was it a 277/480 service MI ? was there a fault on the customer side? and were the customer mains open?

admin wrote:was it a 277/480 service MI ? was there a fault on the customer side? and were the customer mains open?

No it wasn't a 277/480 but they had a crew add a neutral to the srvc so it is now 277/480. The cust mains were not off and apparently there was no fault on their side? We've had issues with the straight 480 srvcs after lightening strikes before and the co. is currently changing them over to 277/480 but this one fed a meter that went out as quadraplex to an overhead line built like our 46k lines at a pump house for a fire suppression system at a big local chemical co. The pump house had it's own meter that didn't blow up. Quickly we pointed our fingers to their 480 built like 46k line and thought they had a tree on 2 phases but it was clear?

by straight 480, you mean delta correct? none of the tranformers had the x2 used? thats what i am thinking of when i hear straight 480. 277/480 is of course a wye, when you said they are changing them to 277/480 they must be changinging out the trans bank? if all they did was add a neutral and tap an x2, or corner ground, then you now have a 240/480 bank with a wild leg of 415. remember a delta can be grounded only one time and if one leg was infact grounded inside because of a lightning strike or a bad wire and someone added a ground at the transformers, then you could of had 2 grounds and boom. another thing is with straight 480, your voltage can only be read phase to phase.

kooman wrote:by straight 480, you mean delta correct? none of the tranformers had the x2 used? thats what i am thinking of when i hear straight 480. 277/480 is of course a wye, when you said they are changing them to 277/480 they must be changinging out the trans bank? if all they did was add a neutral and tap an x2, or corner ground, then you now have a 240/480 bank with a wild leg of 415. remember a delta can be grounded only one time and if one leg was infact grounded inside because of a lightning strike or a bad wire and someone added a ground at the transformers, then you could of had 2 grounds and boom. another thing is with straight 480, your voltage can only be read phase to phase.

You can use 277/480 or 240/480 in a corner grounded bank. Think he's calling straight 480 a corner grounded.

Mike-I showed this to a couple of meter tech trainers earlier and what one guy said that is a 1 in a million deal that happened to him was the customer side had a different leg grounded from the incoming service. Because of the poor soil conditions (caliche) it stayed and worked like this for awhile...then one day after some rain that is when it smoked.

I guess the only fool proof way is to see what's going on within the customer side of things...keep that main open when closing. Something to always be aware of, glad you brought this up.

You can use 277/480 or 240/480 in a corner grounded bank. Think he's calling straight 480 a corner grounded

Please explain a corner grounded wye, thats something new for me.

Basically put all your X2 together and leave it floated then each x1 to a hot leg...ground one of them. 480 is just 480.

Now I will say I've never built one; for some reason all I ever see are 240/480's used but it is in our standard book. There are a couple of straight 240 banks out here lingering in the oil patch.

Lewy needs to chime in here; last I knew in Canada they'll only build wye banks.

very interesting, thank you.

rcdallas™ wrote:Basically put all your X2 together and leave it floated then each x1 to a hot leg...ground one of them. 480 is just 480.

Now I will say I've never built one; for some reason all I ever see are 240/480's used but it is in our standard book. There are a couple of straight 240 banks out here lingering in the oil patch.

Lewy needs to chime in here; last I knew in Canada they'll only build wye banks.

We only supply new Y 3 phase power either 120/208 or 347/600, but 277/480 is a Y voltage. We have some old 600 delta services that we will feed with 347/600, the customer just doesn't use the neutral, but we only do this when a 600 delta trans blows up as we do not carry any 600 delta transformers.

This was a 277/480 3 phase "pad mount" or underground transformer. It has an x2 that wasn't used. The co. was supplying "straight" or "delta" 480 secondary voltage. We've done the same with overhead tubs. After some time our co. realized the delta 480 sec didn't receive lightening real well (like anything else!) and if the meter looked good yet ya had usually 2 fuses blown a worker would try the fuses and the socket would blow up! I guess at times the vts for our metering take a hit but show no signs of damage until ya try it again (not all the time but a good majority)? The co. has now for the last little while hired electrical contractors to rewire the customers sockets for 277/480 and a crew of ours will add the neutral to the service. Somehow this reduces the likely hood of lightening damage (well actually a meter tech told me the other day with the 277/480 change overs they use a meter that's 120v and only has 3-5 amps on it so it's safer for them but not me I guess? )? I believe all of our 480 tubs are 3 bushing 277/480 tubs? We might have 240/480 tubs but I haven't seen one in a long time if we do?

I must admit "corner grounding" isn't a term used here so I'm not familiar with it and I asked someone here once about it and I forget who it was or what they said? Anyway, I'm getting the feeling closing it in is the only real test and I don't like it? The local I had was fed from a riser in the deep right of way and was one of two risers on the same pole that were NOT NUMBERED and dispatch had no idea either? Not to mention the pole they were on was one of the 2 support poles for an isolator bank AND there was a third riser not too far away that we weren't 100% sure didn't feed it?

I wish "climbsome" was here cuz he could describe it better and probably answer the question (cuz he worked here!) but he disappeared when that other site went to hell and he's not one of the "many previous members" byron mentioned in his rag that have returned!

MI-Lineman wrote:I must admit "corner grounding" isn't a term used here so I'm not familiar with it and I asked someone here once about it and I forget who it was or what they said?

Just a fancy word. Think of drawing out your vectors/phasers. You have the delta triangle...3 corners and one of them has a ground on it.

Is there a 4th cutout for grounding the y high side neutral? If not then this could well be your problem sympathetic tripping due to phase bucking, oh tanks going bad due to circulating current, UG tubs jumping of the pad and landing in a parking lot due to ferroresonace are only a few of the many problems.

All of which can be addressed buy tieing the y for your switching then opening when complete.

Hope this helps and as always:

Work safely,

L.A. Martin
Journeyman Div III
CVEC

No Martin this was a padmount and there's no way I know of with our padmounts to tie it in but I think I'm not clear on my question......can or is there a "guaranteed" way in the field to test or check out the meter for a delta 480 socket before I through it in and it goes BANG in my face again? The meter blew up and I'm told it's usually because of the vts used to calculate the...well you know how a meter works, take a shot of lightening? Sometimes the damage is done with the lightening and the socket and meter upon arrival is smoked and others we've had instances where it must be only weakened and it blows when you close in the transformer or bank?

MI-Lineman wrote:No Martin this was a padmount and there's no way I know of with our padmounts to tie it in but I think I'm not clear on my question......can or is there a "guaranteed" way in the field to test or check out the meter for a delta 480 socket before I through it in and it goes BANG in my face again? The meter blew up and I'm told it's usually because of the vts used to calculate the...well you know how a meter works, take a shot of lightening? Sometimes the damage is done with the lightening and the socket and meter upon arrival is smoked and others we've had instances where it must be only weakened and it blows when you close in the transformer or bank?

I'm about to veer in a different direction...this might be healthy.

I'm thinking about this. The best answer I can come up with relates to closing in on anything in general...take every precaution and expect the unexpected. What I mean is always put the most distance you can--like closing a cutout out of the bucket, can you do it on the ground with a long stick?

3 weeks ago I go repair a broke jumper on the high side of a cutout. I cradle and another guy closes the cutout with a long stick on the ground and when he does the cutout splits in half perfectly and goes phase to ground then phase to phase and primary went down. It was a huge ass fire. Tell me you wouldn't of pee'd on your leg if you closed that in out of a bucket with a short stick.

Speaking of meter; forget all the PT/CT meter tech crap. Let's talk house meter 120/240 form whatever it is. You go do a meter set, customer main turned off you check and find 120/120/240 on the line side and line to load 0/0 ( 4-6 volt ghost voltage on digital fluke whatever ) you check and see the load side isn't energized. You determined everything is okay to set and when you go to stab the meter the thing fires up and starts spitting on you because there is something internally wrong with the meter.

I had a new meter start hissing at me maybe less then 2 months ago. I mean I checked everything? I guess the next step I could of done was open the transformer, set the meter and then close the transformer in and if it would of fired up I would of had a great deal of distance between myself and the meter.

Short answer I don't think there is a fool proof way that is 100%.

On padmount xfmr with a switch inside of it I will utilize the door itself as a shield between me and the inside when I go to flip the switch--using what is available right there free of charge.

Closing in stuff with any stick I wont look up incase the joker decides to throw something back at me. When in rubber gloves picking up wire, energized or de energized I wont put myself in series stabbing that automatic.

Wrap a blanket around the meter before energizing if that is your only option ? (hmm I like that idea)

I don't know; not trying to hi-jack the original question--I just don't think there is a fool proof way.

With what LA is saying ferro could be, delta-wye padmount. Does the footage of cable exceed the KVA of the transformer? Was the customer main open or closed ?

What is expect the unexpected? Hell I don't know; just act like a cock roach and feed off of others knowledge and experiences. Them guys who been around the block wtdoor and batts have 6 gears where I have 2. Another subject of itself.

Where is our resident Meter Specialist that carries manual's in her purse on this subject ?

rcdallas wrote:

MI-Lineman wrote:No Martin this was a padmount and there's no way I know of with our padmounts to tie it in but I think I'm not clear on my question......can or is there a "guaranteed" way in the field to test or check out the meter for a delta 480 socket before I through it in and it goes BANG in my face again? The meter blew up and I'm told it's usually because of the vts used to calculate the...well you know how a meter works, take a shot of lightening? Sometimes the damage is done with the lightening and the socket and meter upon arrival is smoked and others we've had instances where it must be only weakened and it blows when you close in the transformer or bank?

I'm about to veer in a different direction.

I'm thinking about this. The best answer I can come up with relates to closing in on anything in general...take every precaution and expect the unexpected. What I mean is always put the most distance you can--like closing a cutout out of the bucket, can you do it on the ground with a long stick?

3 weeks ago I go repair a broke jumper on the high side of a cutout. I cradle and another guy closes the cutout with a long stick on the ground and when he does the cutout splits in half perfectly and goes phase to ground then phase to phase and primary went down. It was a huge ass fire. Tell me you wouldn't of pee'd on your leg if you closed that in out of a bucket with a short stick.

Speaking of meter; forget all the PT/CT meter tech crap. Let's talk house meter 120/240 form whatever it is. You go do a meter set, customer main turned off you check and find 120/120/240 on the line side and line to load 0/0 ( 4-6 volt ghost voltage on digital fluke whatever ) you check and see the load side isn't energized. You determined everything is okay to set and when you go to stab the meter the thing fires up and starts spitting on you because there is something internally wrong with the meter.

I had a new meter start hissing at me maybe less then 2 months ago. I mean I checked everything? I guess the next step I could of done was open the transformer, set the meter and then close the transformer in and if it would of fired up I would of had a great deal of distance between myself and the meter.

Short answer I don't think there is a fool proof way that is 100%.

On padmount xfmr with a switch inside of it I will utilize the door itself as a shield between me and the inside when I go to flip the switch--using what is available right there free of charge.

Closing in stuff with any stick I wont look up incase the joker decides to throw something back at me. When in rubber gloves picking up wire, energized or de energized I wont put myself in series stabbing that automatic.

Wrap a blanket around the meter before energizing if that is your only option ? (hmm I like that idea)

I don't know; not trying to hi-jack the original question--I just don't think there is a fool proof way.

With what LA is saying ferro could be, delta-wye padmount. Does the footage of cable exceed the KVA of the transformer? Was the customer main open or closed ?

Where is our resident Meter Specialist that carries manual's in her purse on this subject ?

Great? I don't like your answer but I like I got an answer just not the answer I would've liked? Uh anyway, I personally choose to close from the air cuz I'd rather feel the heat than have sh!t raining down on me! Earlier this sumer I had a 125a fuse blow and the tail shot out and hit my beautiful truck like someone throwing a 2x2 at it from the air! I had a co-worker get a piece of a 65a fuse through his forearm. He was off for 2 months! Guess it's my preference but if somethings gonna burn down I'd rather be off the "ground" when it comes at me?

So anyway I guess I'll just close in the 480's at the sub?

Thank You! I think?

Yeah...I don't know. Everything situation is different. Don't close in at the sub; the substation could melt down on you. Maybe have the operator do it remotely via SCADA. Then again your portable radio battery could melt down in your hand when you key the PTT button.

I'm just rambling on. I'll go back in my corner and shut up.

rcdallas wrote:Yeah...I don't know. Everything situation is different. Don't close in at the sub; the substation could melt down on you. Maybe have the operator do it remotely via SCADA. Then again your portable radio battery could melt down in your hand when you key the PTT button.

I'm just rambling on. I'll go back in my corner and shut up.

Nice post! U Texans shers fundy!!