Transformer Question

[Myhvacguy1]

I currently have 480VAC running on a 30amp 3 pole breaker. I need to use a transformer to bring it down to 240VAC to run a Warren Heaters heat strip. The specs call for 240VAC and 40 amps. I found one at Carrier but it was only rated to 250VA. Is that large enough to handle the needed amps? Is there a formula I should use to figure this out?


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[BALloyd]

VA ÷ V = A

250 ÷ 240 = 1.042 Amps.

Not even close.



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[VTP99]

Better look closer at the existing line size.

[2sac]

Seems contactor(s) should come into play somewhere in the mix

[Myhvacguy1]

Is it possible to have a qualified electrician take the power at the panel down to 240? In looking at the panel it just said 480 main breaker panel. Had numerous 3 pole breakers, a few 2 pole breakers and 10 single pole breakers.


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[Myhvacguy1]

Seems contactor(s) should come into play somewhere in the mix

Can you please give me a little more detail on what you mean by this?


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[ammoniadog]

Is it possible to have a qualified electrician take the power at the panel down to 240? In looking at the panel it just said 480 main breaker panel. Had numerous 3 pole breakers, a few 2 pole breakers and 10 single pole breakers.


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You can not get 240V from a 480V breaker box. Even if you could, your wires might be too small if they're sized for 30 amps, any you need them to be sized for 40 amps.

You most likely have a 208V or 230V panel near by that can be used. Your wires (if they are the correct size) could probably be run to that panel instead. An electrician would have to look at it to see if that would be possible.

Using BALloyd's formula (ohm's law), you would need at least a 9600VA transformer to do what you wanted to do.

[buford]

Why not just use a heat strip rated for the correct voltage you have?

[2sac]

Can you please give me a little more detail on what you mean by this?


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I was drinking and misread the original post

[Myhvacguy1]

Why not just use a heat strip rated for the correct voltage you have?

On this particular project, the engineer drew in the plans an external duct heater running on 480VAC. The client isn’t happy with the look of this as the ductwork is visible in the space. They are wanting to have us place the heat strip inside the AHU for appearances. The AHU is currently powered by 208vac @ 20Amp and I can’t find a heat strip large enough to heat the space that won’t trip that circuit. I was looking for a way to run the current AHU off of the 480VAC that is powering the duct heater without having to have an electrician run larger wire. No one wants to cover that cost.


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[Snapperhead]

Who the hell does he think will be staring up at the ceilings ? Just put the duct heater in

People are crazy ...

[Poodle Head Mikey]

Is there more than one element in the "strip" ?

And hopefully an even number. <g>

If so; the 240V unit could be re-wired to operate on 480V

PHM
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I currently have 480VAC running on a 30amp 3 pole breaker. I need to use a transformer to bring it down to 240VAC to run a Warren Heaters heat strip. The specs call for 240VAC and 40 amps. I found one at Carrier but it was only rated to 250VA. Is that large enough to handle the needed amps? Is there a formula I should use to figure this out?


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[VTP99]

You're going to be pulling new wire no matter what you do.

[Snapperhead]

Is there more than one element in the "strip" ?

And hopefully an even number. <g>

If so; the 240V unit could be re-wired to operate on 480V

--------

Ewe that's right … that things probly wired up like a xmas tree

[Myhvacguy1]

Who the hell does he think will be staring up at the ceilings ? Just put the duct heater in

People are crazy ...

Snapperhead,
You are correct that people are crazy. However, With that being said, these crazy people are paying the company I work for a lot of money for the finished product and potential future projects are what we’re looking for.
I also agree that most people don’t look at the ceiling but ever since I got into the trade, when I see exposed ductwork, I critique it.


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[Myhvacguy1]

Is there more than one element in the "strip" ?

And hopefully an even number. <g>

If so; the 240V unit could be re-wired to operate on 480V

PHM
--------

This unit has 4 strips in it. Are you serious when you say that? It would have to run the heating elements and the blower motor.


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[Snapperhead]

Oh trust me I've seen my share of people being overly fussy with how it looks , making my job a complete pain in the ass , but the bill also reflects it

"that relay costs 800 dollars ?? "

Yup for You it does …. I mean , Yes , yes it does

[2sac]

On this particular project, the engineer drew in the plans an external duct heater running on 480VAC. The client isn’t happy with the look of this as the ductwork is visible in the space. They are wanting to have us place the heat strip inside the AHU for appearances. The AHU is currently powered by 208vac @ 20Amp and I can’t find a heat strip large enough to heat the space that won’t trip that circuit. I was looking for a way to run the current AHU off of the 480VAC that is powering the duct heater without having to have an electrician run larger wire. No one wants to cover that cost.


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Someone's going to have to. You've already got 208 in the building. If the panel can handle it, add another breaker and pull wire.

[Snapperhead]

This unit has 4 strips in it. Are you serious when you say that? It would have to run the heating elements and the blower motor.


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yes , If you run 2 of the strips in series like a xmas tree it becomes 480 , you know , like batteries in a flashlight , so essentially it makes 1 long strip , but you can only hook up 2 , leave other 2 strips unhooked , then test how many amps shes pulling

We cant draw a diagram in the open forum , or give you wire colors , but hopefully you can read in-between the lines