Need help sizing a transformer. No idea what I'm doing.

[VagPuncher]

Greetings,

Please be patient with me as I have no idea what I'm doing. I'll try my best to explain.

I am in a warehouse that has a 100A 600V primary panel. In the panel there is a 40A 600V breaker that is running the infloor heating.

I was to have a sparky disconnect the infloor heating and use that's 40A breaker to run to a transformer and then to a 108/120V secondary panel.

My question is: what is the appropriate sized transformer I will need? 35KWA?

 

[queequeg152]

absolutly not appropriate to do this yourself.

i had to size a 25kva dry transformer for instrumentation equipment + lighting for a water plant.

its not straight forward. its not trivial and its not something you should be doing.

absolutely hire an electrician for this.

 

[Floridian]

You know why transformers hum?Becuase they don't know the words.The wire size coming out of a step up transformer is considerably smaller than the wire size going into it.Just a tidbit of strange facts to support QQ's advice,if you don't understand them fully they are not to be fucked with by the average ham'n'egger, believe that

 

[YetiOG]

Greetings,

Please be patient with me as I have no idea what I'm doing. I'll try my best to explain.

I am in a warehouse that has a 100A 600V primary panel. In the panel there is a 40A 600V breaker that is running the infloor heating.

I was to have a sparky disconnect the infloor heating and use that's 40A breaker to run to a transformer and then to a 108/120V secondary panel.

My question is: what is the appropriate sized transformer I will need? 35KWA?

I could answer that but it would be totally in bad judgement. If you are asking that you have no buisness doing that.

Also, a wasehouse with 100a service... you have lots to do around there thats not much juice you couldnt run that many lights in there. Call a sparky and get them to sort you out. Theres a reason comercial electricians exsist

 

[OldPhart]

I could answer that but it would be totally in bad judgement. If you are asking that you have no buisness doing that.

Also, a wasehouse with 100a service... you have lots to do around there thats not much juice you couldnt run that many lights in there. Call a sparky and get them to sort you out. Theres a reason comercial electricians exsist

Not much juice??? Depending on what else you have to run, it could probably hold a 100kw grow. I can't comprehend these 50 or 100+ light grows, I still consider a 10 light grow to be a large grow. Whole new world out there now! I'm happy to play with my little 600w box.

 

[YetiOG]

Not much juice??? Depending on what else you have to run, it could probably hold a 100kw grow. I can't comprehend these 50 or 100+ light grows, I still consider a 10 light grow to be a large grow. Whole new world out there now! I'm happy to play with my little 600w box.

H said a warehouse with 100 amps thats like a garage not really a warehouse lol...

Whats not to comprehend about large grows some people have money to put them up and places to sell the dope. Dosent mean its good but they serve a purpose. 10 lights is large in a home but in a warehouse 10 lights is... well 10 lights doesnt fill a warehouse anyway

 

[OldPhart]

H said a warehouse with 100 amps thats like a garage not really a warehouse lol...

I think you missed the 600V part, that makes the 100A a VERY real amount of power. ***this is why everyone, myself included is suggesting professional help getting the power delivered to a distribution panel that would be usable.*** I actually broke out the calculator, and it wasn't as high as I estimated. @ 100A/3 phase/600v, you could deliver 104 KW. By the time you de-rate it to 80% and allow for equipment besides lights, I would bet you could get around 55-60 1k lights running. That is a bit more than a garage

 

[YetiOG]

I think you missed the 600V part, that makes the 100A a VERY real amount of power. ***this is why everyone, myself included is suggesting professional help getting the power delivered to a distribution panel that would be usable.*** I actually broke out the calculator, and it wasn't as high as I estimated. @ 100A/3 phase/600v, you could deliver 104 KW. By the time you de-rate it to 80% and allow for equipment besides lights, I would bet you could get around 55-60 1k lights running. That is a bit more than a garage

No i didnt miss the part about 600v but as you noticed you couldnt run 100 × 1000 hps

Also you are only factoring power for lights what about the AC and everything else you are only looking at how many lights you can hang you arent factoring that other things need electrical service.

Regardless im not giving the OP potentially dangerous info. I could tell him what hes looki g for but what hes trying to do, is best left to someone who has a clue. The thread name is "i have no idea what im doing"... so call a pro... we can quabble about what he can service with that much power but at the end of the day, he needs to just call a sparky

 

[VagPuncher]

Okay.

First of all. I would never do the install myself. My sparky is very hard to get in to the warehouse. He's never gonna come to size a transformer. If I have everything there for him to work on he will show up and since he's my friend and I trust him I HAVE to use him. Security issues.

Okay. This is the primary 100 A 600 V.

 

[VagPuncher]

You see the 50A 600V breaker on the left of the panel? That is going to this 45KWA transformer.

Then it comes back from the transformer to this secondary panel which is 208/120V 3 phase.

 

[VagPuncher]

I get 125 A 3 phase at 120V on that secondary panel.

Now look at the 600V panel again. This time the 40A breaker on the right. That is connected to a infloor heating boiler. I want to disconnect the infloor heating and use that 40A breaker to run a second transformer.

How big of a transformer do I need? I want to copy the work thats already been done but with a 40A breaker instead of 50A.

I will buy the transformer and another 208/120V panel and then call my sparky to do all the work.

 

[Jhhnn]

Okay.

First of all. I would never do the install myself. My sparky is very hard to get in to the warehouse. He's never gonna come to size a transformer. If I have everything there for him to work on he will show up and since he's my friend and I trust him I HAVE to use him. Security issues.

Okay. This is the primary 100 A 600 V.

I think you're getting it right. Amps x volts equal watts. Your primary panel will deliver 50x600, 30KWH. If your transformer is rated at 35KWH or greater you should be good to run 26.4KWH (80%) from your secondary 208/120 panel.

Edit- that 26.4 figure doesn't account for transformer inefficiency. Consult the label to figure that out. Chances are good that the main breakers will trip if you try to run more than 80% continuous.

 

[OldPhart]

I get 125 A 3 phase at 120V on that secondary panel.

Now look at the 600V panel again. This time the 40A breaker on the right. That is connected to a infloor heating boiler. I want to disconnect the infloor heating and use that 40A breaker to run a second transformer.

How big of a transformer do I need? I want to copy the work thats already been done but with a 40A breaker instead of 50A.

I will buy the transformer and another 208/120V panel and then call my sparky to do all the work.

Why not replace/add a new breaker to mirror everything that is already there? May as well max it out, no sense of leaving that last bit of capacity where you can't utilize it. I would leave the breaker for the heating circuit in the box, just disconnect the wires from the breaker to keep someone from being able to overload the panel. Other than the cost of the breaker, I don't see this adding that much cost to the project. If your like most people, you will find a use for the extra capacity.

 

[queequeg152]

go to the mike holt website and look into sizing service transformers. you will see why i reccomended professional help. its not just volt amps multiplied by some constant.

you need to take a bunch of shit into account. in my case it was such a small transformer... and a dry transformer 208 to 120v, it fell into reletivly simple code rule making. even so we had the specs and control schematic run through the electrical contractors master prior to issuing a bid.

if your guy is not willing to size it for you, then find someone who will. ive never had to do something like this personally, but perhaps you could start by calling the local electrical supply houses.

 

[hvac guy]

45KVA transformer, depending on degree rise and if you are running high harmonic loads.