POCO Transformer primary

[meternerd]

Is transformer tank also isolated from grounded secondary conductor?

How far apart are ungrounded conductors, if they don't want a lineman to be able to contact an ungrounded and a grounded conductor that is kind of understandable, but based on same theory they should have all ungrounded conductors at least 7 - 8 feet apart just to prevent a lineman with a long arm span from being able to contact both at same time - and that is not counting any tools or other equipment he may have in his hands.

I am not a lineman but have seen many times where they put insulating devices on exposed conductors, both grounded and ungrounded when necessary. I have also seen many times where the lines are de energized and ground jumpers are installed between all conductors, on both sides of the work if it is capable of being fed from either direction.

Yes, the secondary neutral bushing is isolated from the tank and bonded to the common primary grounded neutral with a bare copper jumper. So, the question is, why isn't a bare ground jumper just as dangerous as a grounded tank? Still a chance of incedental contact. Go figure! Yes, we do cover hot phases when working energized primary. De-energizing a line is not always practical. That's why linemen have rubber cover, rubber gloves and sleeves, hot sticks, etc. When I worked in Alaska, tanks were grounded and bonded to neutral with no more danger than how they do it here. I think it's just so California can be different. Bureaucrats making rules. With all of the new arc flash rules, PPE rules and Cal OSHA rules, I'm glad I'm almost ready to retire. It's a wonder I'm still alive.

Oh, by the way...ground jumpers on either side of the work area seems like a good idea, but EPG grounding is still the best way to go. If the lines were to come hot with phases grounded, the voltage across the grounds and anything else (lineman) in parallel would be 7200 until the protective device clears the fault. Kirchoff's Voltage Law. As the saying goes...Identify, Isolate, Test and Ground. It's the Ground part that has changed from parallel grounds to Equi-Potential Grounding.

 

[kwired]

Yes, the secondary neutral bushing is isolated from the tank and bonded to the common primary grounded neutral with a bare copper jumper. So, the question is, why isn't a bare ground jumper just as dangerous as a grounded tank? Still a chance of incedental contact. Go figure! Yes, we do cover hot phases when working energized primary. De-energizing a line is not always practical. That's why linemen have rubber cover, rubber gloves and sleeves, hot sticks, etc. When I worked in Alaska, tanks were grounded and bonded to neutral with no more danger than how they do it here. I think it's just so California can be different. Bureaucrats making rules. With all of the new arc flash rules, PPE rules and Cal OSHA rules, I'm glad I'm almost ready to retire. It's a wonder I'm still alive.

Oh, by the way...ground jumpers on either side of the work area seems like a good idea, but EPG grounding is still the best way to go. If the lines were to come hot with phases grounded, the voltage across the grounds and anything else (lineman) in parallel would be 7200 until the protective device clears the fault. Kirchoff's Voltage Law. As the saying goes...Identify, Isolate, Test and Ground. It's the Ground part that has changed from parallel grounds to Equi-Potential Grounding.

There may be more to it than just ground jumpers on either side of the work, I mostly just observe the ground jumpers when driving down the road and don't know everything that has been done.