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 Post subject: Utility Issues
PostPosted: Thu Oct 18, 2012 11:51 am 

Joined: Thu Oct 18, 2012 11:44 am
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Hi ALL!! great site you have going here, glad I stumbled upon it. I am dealing with a utility company in the US that is giving me quite a hard time on locating information about on-site transformers like size,volatage,impedance. Pretty standard stuff here. He also told me they keep no record of any of that information in their database and they dont conform to the NEC. I am aware that utlity companies fall under the nesc and not the nec. Any ideas what kind of sections from the NESC or IEEE I can push back at him with to get this basic information?


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PostPosted: Fri Oct 19, 2012 3:13 am 
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Joined: Tue Oct 26, 2010 9:08 am
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Location: North Carolina
No, and it would not be wise to go in that direction because depending on the upstream side (frequently network distribution), the answer will be "it depends". Did you try asking for available short circuit current instead? I don't think I've ever asked a utility for their transformer sizes.

There is no labeling requirement for SCCR under NESC like there is in the NEC, either. Although some (many these days) utilities do indeed have a complete power system analysis software program with as complete of a system model as they can make it, many of the smaller ones even today do not have this. If you have the available fault current (the utility should have this), then there is a table in section 410 that can give an approximate incident energy value for overhead distribution lines. They are probably in violation of OSHA if they don't have this information, same as end users are if they don't maintain similar information for using 70E.

As for any rules and regulations, I would recommend forgetting about looking in NESC. It definitely has rules on how to do things but it is oriented towards the utility protecting it's own equipment and people. I would look towards OSHA Subchapter R for what you are looking for. Also, if the utility line crews are ever out doing work or working with you, make friends with them. They usually know a lot more about the system than the engineers. There is also usually a big divide between the operations, maintenance, and relaying departments. So you might just be talking to the wrong group.


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PostPosted: Mon Oct 22, 2012 5:03 am 

Joined: Mon May 21, 2012 5:00 pm
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I have some clients who get their low voltage from a utility owned transformer. In the past I have been able to get the transformer and primary fuse data from the utility so I can model and calculate incident energy at the secondary main breaker (customer owned) as well as provide coordination. Lately the utilities are no longer giving me this information. They will only provide short circuit data at the point of common coupling. My guess is that the utility does not want to be liable for their protective devices working to provide arc flash protection at the customer's equipment.


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PostPosted: Mon Oct 22, 2012 5:11 am 

Joined: Wed May 06, 2009 12:12 pm
Posts: 26
Location: Tennessee
If you have pad mounted transformers you can get a utility company electrician to come out and open the doors. Each pad mount should have a name plate on the low voltage side. You can use a digital camera with a zoom lens and take a picture of the label.


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PostPosted: Mon Oct 22, 2012 7:02 am 
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Joined: Fri Apr 15, 2011 7:43 am
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Location: Colorado
Getting utilty information can be difficult and varied. Our local utility will only give infinite bus fault data on thier distribution system. Others I have dealt with do not keep any information and have to physically go to the gear and look at it - sometimes for a cost. Your best bet is to send the utility a letter or email requesting the information with a disclaimer stating you only want the data as it is today and understand it may change at any time. A gentle approach is generally best because they are key to getting your information. You may only get the available fault current!

I am working a orver 500 arc flash studies and the utility data is the hardest data to collect.


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PostPosted: Tue Oct 23, 2012 8:53 am 
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Ed Pramik wrote:
I have some clients who get their low voltage from a utility owned transformer. In the past I have been able to get the transformer and primary fuse data from the utility so I can model and calculate incident energy at the secondary main breaker (customer owned) as well as provide coordination. Lately the utilities are no longer giving me this information. They will only provide short circuit data at the point of common coupling. My guess is that the utility does not want to be liable for their protective devices working to provide arc flash protection at the customer's equipment.


Don't make the assumption that what one person at a utility says has any relation to what another will in terms of policy. I usually deal with one, very large utility in california. Depending on who I talk to, I have been told that
1:They really are not sure what equipment they have in that area
2:THey pull a number off of a table they have that is based on service entrance rating
( which frequently has no relationship to the serving transformer size)
3: That I will have to fill out an application and pay $500 to get that information.
(That turned around ABRUPTLY when I asked for the exact tarrif that allowed for that charge.
But I have been hit with that from one particular district several times.)
4: Exact transformer size, impedance, complete upstream fault information for either of the two alternate sources, transformer fuse information and upstream relay information for the two possible sources.

In the case of 1: above, I think the guy was being honest. THat was a part of their system that has elements dating back to the thirties, if not the twenties, and they still prvide DC and Steam to some clients, in a congested urban area.

2: is a problem. In one project I am working on now (OK waiting for submittials on) the utility has given me a fault number that is larger than the new transformer they are putting in will allow, even if they have an infinite bus, and ANY reasonable impedance.


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PostPosted: Wed Oct 24, 2012 7:16 am 

Joined: Thu Oct 18, 2012 11:44 am
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engrick wrote:
Getting utilty information can be difficult and varied. Our local utility will only give infinite bus fault data on thier distribution system. Others I have dealt with do not keep any information and have to physically go to the gear and look at it - sometimes for a cost. Your best bet is to send the utility a letter or email requesting the information with a disclaimer stating you only want the data as it is today and understand it may change at any time. A gentle approach is generally best because they are key to getting your information. You may only get the available fault current!

I am working a orver 500 arc flash studies and the utility data is the hardest data to collect.


This is something I know now ( I also am working on approx 500 studies). I have called utilities from all over the country and it seems just this one state and their two major utilities are a pain to deal with. After going back anbd forth for a while, he finally agreed to help me get the data from the nameplates. I assure you I was being very gentle but this gentleman was just , what I would called disgusted and appaled in general that I was trying to get this information. He had a hard time believing that I am able to get any utility at all to get me this info. In general I posted this to see if anyone knew any info on sections of NESC OSHA IEEE that could help but the feedback has been perfect.


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PostPosted: Mon Oct 29, 2012 1:02 pm 

Joined: Thu Feb 04, 2010 5:00 pm
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Location: Camp hill Pa
Generally the Utility does not give Fuse data. This is due that in an emergency situation (As I sit in Mid-Pa, wanting for Sandy) a lineman may install a different fuse to get a line back in service and sometimes someone will go back and reinstall the correct fuse, and sometimes not. However they will provide short circuit data if requested by letter. I have never had one flat out refuse to do so in writing from jobs in alaska to Texas to Pennsylvania. It is amazing to find the actual short circuit current available at some of the service drops. In Maryland, I observed a 350 kva 120/240 volt transformer feeding a block of small duplexes and townhouses.


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PostPosted: Fri Nov 02, 2012 12:13 pm 
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Joined: Tue Jan 13, 2009 5:00 pm
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PaulEngr wrote:
Did you try asking for available short circuit current instead?


You'll likely get worst case for equipment sizing, not what you need for arc flash.

BISAM wrote:
If you have pad mounted transformers you can get a utility company electrician to come out and open the doors. Each pad mount should have a name plate on the low voltage side. You can use a digital camera with a zoom lens and take a picture of the label.


Just be aware that when it needs to be replaced, the new service transformer may have different specs.


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PostPosted: Tue Nov 06, 2012 9:29 am 
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beng wrote:
This is something I know now ( I also am working on approx 500 studies). I have called utilities from all over the country and it seems just this one state and their two major utilities are a pain to deal with. After going back anbd forth for a while, he finally agreed to help me get the data from the nameplates. .


Sounds rather a lot like you are talking California & SCE and PG&E.
If so, typically there is no problem getting information, once you actually get to talk to some one.
OTOH it sounds like you got him to answerthe phone, so it probably isn't PG&E at least.


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PostPosted: Tue Nov 06, 2012 1:11 pm 

Joined: Thu Oct 18, 2012 11:44 am
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JKlessig wrote:
Sounds rather a lot like you are talking California & SCE and PG&E.
If so, typically there is no problem getting information, once you actually get to talk to some one.
OTOH it sounds like you got him to answerthe phone, so it probably isn't PG&E at least.

No, its a different state totally. I havent had any issues in California


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