Code Violation?

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spotted123

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Pad mounted transformers- 12.4kv primary-480vac secondary. Co-worker believes grounding and bonding is in violation. While I agree its sloppy work but not a violation. What do you think?
 

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I don't see anything with the grounding/bonding or maybe I am not looking at it with an experienced eye.

However, on the right side, the smaller conductors are sharing a home with the larger conductors. The lugs probably are not designed for two conductors.
 
Is this transformer subject to NEC or is it POCO transformer?

Is the secondary 480 volt delta? If so is it an ungrounded system? If it were a 480/277 I would expect to see a terminal labeled X0 instead of just an unmarked lug on the tank. If it is corner grounded then depending if this is utility controlled or NEC application we may see the bond in the transformer housing, but either way one of the phases should be using white or gray as color of the grounded conductor.

What is with the white mark on one of the brown leads and one of the orange leads?
 
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kwired said:
Is this transformer subject to NEC or is it POCO transformer?

Is the secondary 480 volt delta? If so is it an ungrounded system? If it were a 480/277 I would expect to see a terminal labeled X0 instead of just an unmarked lug on the tank. If it is corner grounded then depending if this is utility controlled or NEC application we may see the bond in the transformer housing, but either way one of the phases should be using white or gray as color of the grounded conductor.

What is with the white mark on one of the brown leads and one of the orange leads?
Click to expand...

These are not POCO owned. The secondary is a 480 volt delta ungrounded system supplying an outdoor switchboard. I have no idea what the white tape on the brown & orange wire means.
 
spotted123 said:
These are not POCO owned. The secondary is a 480 volt delta ungrounded system supplying an outdoor switchboard. I have no idea what the white tape on the brown & orange wire means.
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I suspected it was ungrounded. Biggest thing I can see is the two conductors in one lug that I'm fairly certain is not designed for two conductors.

If the conductors on the secondary are in parallel - you may want to double check the size of the EGC's - they could be a little small. Each one needs sized per the overcurrent device, not the conductors in the individual raceway.
 
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If it's a grounded Wye primary, why are the concentric neutrals grounded and bonded to the enclosure? What's up with the little green wires in with the primary conductors? You wouldn't see that in a POCO transformer. What is it hooked to on the other end? Seems like a parallel path for neutral current with the concentric neutrals. Shouldn't it be treated like a feeder? Guess I'm just used to services.
 
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Oh....I just looked at a picture of bonding for a SDS. Seems weird to have a ground wire in with primary medium voltage cable, but if I'm looking at it right, I guess it's required. I'll stick to services.
 
meternerd said:
Oh....I just looked at a picture of bonding for a SDS. Seems weird to have a ground wire in with primary medium voltage cable, but if I'm looking at it right, I guess it's required. I'll stick to services.
Click to expand...
I was thinking about that some but did not comment, no real experience with medium voltages.

But I think the concentric neutral is also bonded to this additional EGC, can't quite tell for certain. If so there really isn't any purpose of running the separate EGC - it has become parallel to the concentric neutral. Another thing to consider is whether or not the transformer has Wye primary that actually needs a neutral connected to it or if it only needs the three phase conductors. If it needs a neutral then in NEC applications you need a neutral that is isolated from the EGC. In that case I would think (again not having any real experience with medium voltage) that it may be wiser to run an additional neutral conductor (may even need to be MV conductor) and use the concentric conductor(s) as the EGC.
 
Since you are not a POCO, I don't believe you can use the white potential tap wire on the yellow LV leg as a hot wire. Even if you are using it for a metering/relaying source. If you wrapped a piece of yellow tape around it on each end, it might be ok. Is the voltage rating of the cable / cord high enough for an UNGROUNDED 480 delta? Probably if it is 600V. Not if it is 300V.

I don't see anything exciting on the HV side. The grounds connected to the HV cables are just the shields. No neutral to be seen. The HV Red/White/Blue is standard POCO phase marking. [Go look at a phase rotation meter]
 
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I am certainly not positive on this as there have been changes in '08-'11'-14, but it appears to me that the common supply size bonding jumper to the transformer case is undersizd based on '11 250.30(B) referencing 250.30(A) referencing 250.102(C),
IMO, it should be sized based on the sum of your phase conductors.
 
fmtjfw said:
I don't see anything exciting on the HV side. The grounds connected to the HV cables are just the shields. No neutral to be seen. The HV Red/White/Blue is standard POCO phase marking. [Go look at a phase rotation meter]
Click to expand...

If you're not familiar with underground primary cable, here's a bit of info....the "shield" as you call it, is the neutral on a grounded Wye primary. That's why a single phase transformer only has one cable going to it. Called a concentric neutral. The cable is built like a giant coax cable, but it has two conductors. The center conductor is the phase and the outer "shield" is the neutral. Separated by insulation and semi-conducting sheathing that reduces losses. Some Wye Delta transformers have a separate H0 neutral bushing that is insulated and externally bonded to the enclosure, and others are internally bonded. I like externally bonded, because you can lift the bond and megger the transformer windings while they're not grounded. Also, primary phase marking is not necessarily RWB on the primary. White is usually reserved for neutral to eliminate confusion. We use Red/Yellow/Blue. You don't use rotation meters on medium voltage cables. Why they colored them RWB is anyone's guess. Probably because it's easy to remember (if you're an American). Not trying to be picky...just that some folks might not know. Gotta go try to get some sleep...forest fire smoke is killing me!
 
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kwired said:
I was thinking about that some but did not comment, no real experience with medium voltages.

But I think the concentric neutral is also bonded to this additional EGC, can't quite tell for certain. If so there really isn't any purpose of running the separate EGC - it has become parallel to the concentric neutral. Another thing to consider is whether or not the transformer has Wye primary that actually needs a neutral connected to it or if it only needs the three phase conductors. If it needs a neutral then in NEC applications you need a neutral that is isolated from the EGC. In that case I would think (again not having any real experience with medium voltage) that it may be wiser to run an additional neutral conductor (may even need to be MV conductor) and use the concentric conductor(s) as the EGC.
Click to expand...

Well, here again, I guess I'm looking at it from a POCO perspective. If it's 12.4KV phase to phase, it must be a grounded 12,470/7200 Wye source. Seems weird to have a Delta/Delta, but maybe so.
 
meternerd said:
If you're not familiar with underground primary cable, here's a bit of info....the "shield" as you call it, is the neutral on a grounded Wye primary. That's why a single phase transformer only has one cable going to it. Called a concentric neutral. The cable is built like a giant coax cable, but it has two conductors. The center conductor is the phase and the outer "shield" is the neutral. Separated by insulation and semi-conducting sheathing that reduces losses. Some Wye Delta transformers have a separate H0 neutral bushing that is insulated and externally bonded to the enclosure, and others are internally bonded. I like externally bonded, because you can lift the bond and megger the transformer windings while they're not grounded. Also, primary phase marking is not necessarily RWB on the primary. White is usually reserved for neutral to eliminate confusion. We use Red/Yellow/Blue. You don't use rotation meters on medium voltage cables. Why they colored them RWB is anyone's guess. Probably because it's easy to remember (if you're an American). Not trying to be picky...just that some folks might not know. Gotta go try to get some sleep...forest fire smoke is killing me!
Click to expand...

After looking at it again, maybe it IS a Delta primary. The wire bonding the concentric to the ground is pretty small for it to be a neutral. Nice if we could see the nameplate. Oh well....if it is, forget everything I said (if you haven't already).:D
 
fmtjfw said:
Since you are not a POCO, I don't believe you can use the white potential tap wire on the yellow LV leg as a hot wire. Even if you are using it for a metering/relaying source. If you wrapped a piece of yellow tape around it on each end, it might be ok. Is the voltage rating of the cable / cord high enough for an UNGROUNDED 480 delta? Probably if it is 600V. Not if it is 300V.

I don't see anything exciting on the HV side. The grounds connected to the HV cables are just the shields. No neutral to be seen. The HV Red/White/Blue is standard POCO phase marking. [Go look at a phase rotation meter]
Click to expand...
The white wire for the potential tap appears to be part of a flexible cord. The use of white color would be permitted but needs to be reidentified, but the use of flexible cord is probably not permitted here, unless there is something we can't see that would justify it's use, seems pretty unlikely though.

meternerd said:
If you're not familiar with underground primary cable, here's a bit of info....the "shield" as you call it, is the neutral on a grounded Wye primary. That's why a single phase transformer only has one cable going to it. Called a concentric neutral. The cable is built like a giant coax cable, but it has two conductors. The center conductor is the phase and the outer "shield" is the neutral. Separated by insulation and semi-conducting sheathing that reduces losses. Some Wye Delta transformers have a separate H0 neutral bushing that is insulated and externally bonded to the enclosure, and others are internally bonded. I like externally bonded, because you can lift the bond and megger the transformer windings while they're not grounded. Also, primary phase marking is not necessarily RWB on the primary. White is usually reserved for neutral to eliminate confusion. We use Red/Yellow/Blue. You don't use rotation meters on medium voltage cables. Why they colored them RWB is anyone's guess. Probably because it's easy to remember (if you're an American). Not trying to be picky...just that some folks might not know. Gotta go try to get some sleep...forest fire smoke is killing me!
Click to expand...
Marking primary phases will correspond to specific secondary phases which they will connect to a rotation meter that most likely has RWB leads.

meternerd said:
After looking at it again, maybe it IS a Delta primary. The wire bonding the concentric to the ground is pretty small for it to be a neutral. Nice if we could see the nameplate. Oh well....if it is, forget everything I said (if you haven't already).:D
Click to expand...
If the install is covered by NEC and the primary utilizes the neutral, we must have separate grounded and grounding conductors, there should be a service disconnecting means somewhere upstream, and the primary neutral can not be bonded to the enclosure, the short version of what I was trying to point out earlier. This all started with the questioning of the green wire pulled with the primary cables.
 
[Marking primary phases will correspond to specific secondary phases which they will connect to a rotation meter that most likely has RWB leads.]

In my world, we always mark primary with the same colors regardless of voltage and set rotation CW ABC at loads. I don't tkink there's an industry standard color code. I have never seen Wh used as a phase, though. If it's an existing service that requires reverse rotation, we put a big sticker saying so on the meter panel. In the field, primary phasing can be a real headache if a standard is not used everywhere because switching of primary between subs must phase when being paralleled. We just went through our entire system identifying phases from each substation to every switch where paralleling can happen and put new colored phasing tape on every connection. Took months. Rotation is only half of the issue. A must be A, etc. Otherwise, the protective relaying can give bogus information on which phase is faulted. That can send the line crews on a wild goose chase. There are a few spots where phasing is incorrect and can't be rewired due to customer loads, so we put BIG "Does Not Phase" signs on the poles or padmount switches to help prevent smoke and flames.


[If the install is covered by NEC and the primary utilizes the neutral, we must have separate grounded and grounding conductors, there should be a service disconnecting means somewhere upstream, and the primary neutral can not be bonded to the enclosure, the short version of what I was trying to point out earlier. This all started with the questioning of the green wire pulled with the primary cables.[/QUOTE]

I kinda think it is grounded Wye because 12.4 primary voltage means it's fed from a 12,470/7200 Wye transformer. You would expect the neutral to be grounded. If there is a disconnect ahead of the MV and you don't need a neutral at the load, can you not use the neutral? In that case, the "shield" seems to be being used as an EGC. Weird.
 
meternerd said:
[Marking primary phases will correspond to specific secondary phases which they will connect to a rotation meter that most likely has RWB leads.]

In my world, we always mark primary with the same colors regardless of voltage and set rotation CW ABC at loads. I don't tkink there's an industry standard color code. I have never seen Wh used as a phase, though. If it's an existing service that requires reverse rotation, we put a big sticker saying so on the meter panel. In the field, primary phasing can be a real headache if a standard is not used everywhere because switching of primary between subs must phase when being paralleled. We just went through our entire system identifying phases from each substation to every switch where paralleling can happen and put new colored phasing tape on every connection. Took months. Rotation is only half of the issue. A must be A, etc. Otherwise, the protective relaying can give bogus information on which phase is faulted. That can send the line crews on a wild goose chase. There are a few spots where phasing is incorrect and can't be rewired due to customer loads, so we put BIG "Does Not Phase" signs on the poles or padmount switches to help prevent smoke and flames.


[If the install is covered by NEC and the primary utilizes the neutral, we must have separate grounded and grounding conductors, there should be a service disconnecting means somewhere upstream, and the primary neutral can not be bonded to the enclosure, the short version of what I was trying to point out earlier. This all started with the questioning of the green wire pulled with the primary cables.
Click to expand...

I kinda think it is grounded Wye because 12.4 primary voltage means it's fed from a 12,470/7200 Wye transformer. You would expect the neutral to be grounded. If there is a disconnect ahead of the MV and you don't need a neutral at the load, can you not use the neutral? In that case, the "shield" seems to be being used as an EGC. Weird.[/QUOTE]

POCO's around here use RWB because the rotation meter has those colors for leads - and though they don't connect that meter to the primary voltage, they still use same colors - just because - I guess. What I don't like about that is they sometimes mark leads in equipment that I provide and have inspected , just in case they ever need to replace something on their end they will check rotation at this equipment and the reason they mark it, problem is my inspector sees their white tape on one of my ungrounded conductors and asks me what that is all about:(

Neutrals and equipment grounds - unfortunately when meduim voltage is involved the NEC still has same basic rules as for below 600 volts. There will be a service disconnecting means ahead of such a transformer if it is something NEC applies to. May or may not be immediately before the transformer but will be one someplace. If the load supplied requires a neutral to operate, it will not be the bare conductor of a cable assembly beyond the service equipment - it will be an insulated conductor. The grounded conductor can not be used for equipment grounding beyond the system bonding jumper.

I don't know what is common practice for over 600 volts because I don't do that work, but those are the rules. I guess it is now over 1000 volts in 2014 NEC.

230.200 General.
Service conductors and equipment used on circuits exceeding 1000 volts, nominal, shall comply with all the applicable provisions of the preceding sections of this article and with the following sections that supplement or modify the preceding sections. In no case shall the provisions of Part VIII apply to equipment on the supply side of the service point.
Click to expand...

That section there tells us the rules in previous sections for less then 1000 volts are still the general rule unless something in part VIII says otherwise. I didn't see anything in part VIII that allows for use of the grounded conductor for equipment grounding purposes. If is intended to carry current during normal operation it is a grounded conductor and a separate EGC is needed.
 
spotted123 said:
These are not POCO owned. The secondary is a 480 volt delta ungrounded system supplying an outdoor switchboard. I have no idea what the white tape on the brown & orange wire means.
Click to expand...



Ok, this is delta. Sorry about the scattered reply, just opened the thread haven't read it all.


Its not a violation, however on most delta services bond wires aren't run from the switchgear to the transformer... at least this is how utilities do it. Most utility owned delta secondary PAD and pole pig banks only have 3 wires coming from the customer and nothing else. In fact some POCOs even discourage it, I will give an example.


However, as far as I know tying the secondary EGC to the HV EGC is not a violation. Whether its desirable or not is based on engineering requirements.
 
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