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Re: [TCML] Pole pigs


That’s funny. I am a middle aged IBEW apprentice electrician (apprentisaurus, if you will😉). I was a municipal firefighter for nearly 29 years until retiring last year. As I have enjoyed tinkering around with high voltage and Tesla coils for over 30 years now and I was not physically (nor economically) ready to completely retire, I couldn’t think of a better career choice than being a commercial electrician! I’m in my second year of apprenticeship of the five year journey toward journeyman!

On to your questions. You seem to have the right idea on how to hook up your pole mount transformer ‘backwards’ to power a large SG Tesla coil system. I would say that most coilers prefer the double-eared (a separate high voltage bushing for each of the H leads) transformers for this purpose, due to the fact that the RF ground (which is tied to the base of the primary coil) is supposed to be dedicated and kept separate and isolated from the mains 60 hz ground. With H2 bonded to the exterior tank, the exterior tank assumes RF ground potential, which can sometimes be at several kV of RF potential in relation to mains ground, depending on such things as ground impedance. However, this is not an insurmountable problem for you. You may just want to keep the body of your transformer insulated/isolated from the earth ground. The RF potential isn’t really as much of an electric shock hazard as it is a startling hazard, as you can get nasty little stings and burns from the small arcs that may be drawn from your fingers if you happen to touch any exposed metal surface that’s in electrical contact with the tank’s outer surface while your coil is running! With each of the H terminals having their own standoff bushing, as opposed to one being bonded to the tank, the tank can be bonded to the mains 60 hz ground while H(2) can be bonded to dedicated RF ground. 

And yes, you will need to remove the tank grounding strap from the center low voltage bushing and simply use the two outer low voltage bushings for your 240 volt input while leaving your center bushing floating. Btw, what is the kVA and voltage rating of your transformer? 

And finally, you also have the right idea about external ballasting, as without external ballasting, the pole transformer would impart a near dead short to the 240 volt input when the spark gap fires!

David Rieben 

Sent from my iPhone

> On Dec 9, 2018, at 4:46 PM, Tyler LaVite <tlavite@xxxxxxxxx> wrote:
> Ahh makes sense it’s hard to tell on people’s videos on YouTube no one ever really goes over the exact wiring of them. I’m just use to hooking them up the correct way at work never back feeding them ya know lol just trying to cover everything before I power up for the first time.
> Sent from my iPhone
>> On Dec 9, 2018, at 1:49 PM, Brandon Bebault via Tesla <tesla@xxxxxxxxxx> wrote:
>> My experience with case grounded equipment was that I needed to lift the grounding for my coil to work. I had these 25kvdc GE capacitors that were case ground or (h2) and when they were on the grass I couldn’t get the coil to work when I built this rack system with the Capacitors lifted on rubber wheels the coil worked. Not absolutely sure if this played a part but I did see small arcs come from the case to the rack on my last performance. 
>> -Brandon Bebault
>> Santa Rosa, California. 
>> Sent from my iPhone
>>> On Dec 9, 2018, at 9:36 AM, Tyler LaVite <tlavite@xxxxxxxxx> wrote:
>>> Hello I’d like to start out by saying I am a journeyman IBEW electrician and work closely everyday with a crew of linemen. So I am well aware of safety issues and the dangers of distribution transformers. I have a distribution transformer I’m wanting to wire up and eventually use on my Tesla coil once the weather outside gets better. My question is exactly how to wire it up. It is a single bushing transformer so it has one high leg bushing H1 and the other end of the high side is bonded to the tank so the tank is H2. My plan is to feed it with 240v to both the low side inputs and just leave the neutral leg alone... one question though since the tank is H2 do I need to remove the bonding strap that bonds the tank case to the neutral? Also I plan on ballasting the transformer with a couple large choke transformers I got out of a 30kva battery backup system. 
>>> Does it sound like I’m on the right track here or am I completely  wrong? I deal with this stuff everyday just not use to running something like this in reverse ya know just want to cover everything before I throw the switch.
>>> Thank you!
>>> Sent from my iPhone
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