Tap off 277V site lights to 120V receptacle

[FlyWhale]

Hey guys, hope everyone is well. I'm scratching my head over this...

Let's say I have 277v site lights with 30 amp overcurrent protection and I want to install a 120v receptacle off of the 277v circuit. The receptacle is for cameras on the light poles. There will be one camera per light pole.

How would one go about achieving that?

I figure a disco with fuses going to a 25VA step down transformer.... then to a 15A GFCI receptacle... but this does not sound right.

Any advice is greatly appreciated.

 

[LarryFine]

Secondary requires a GES.

Wild: Auto-transformer?

Extra-wild: 120v tap on ballast?

 

[FlyWhale]

Yes an auto transformer.

I don't follow when you say 120v on ballast...

 

[LarryFine]

I don't follow when you say 120v on ballast...

Many large-format light ballasts have multi-voltage primaries. If you supply the 277v tap with 277v, the other taps will output their respective voltages (behaving as an auto-transformer) (along with the neutral, of course).

Granted, they're not designed to be used that way, but . . .

 

[Another C10]

I want to install a 120v receptacle off of the 277v circuit. The receptacle is for cameras on the light poles. There will be one camera per light pole.

As others mentioned a transformer, the tough part is do you add a small transformer on every pole with a small disconnect or maybe just pull in a separate 120v circuit throughout the pole system.

 

[hbiss]

Many large-format light ballasts have multi-voltage primaries. If you supply the 277v tap with 277v, the other taps will output their respective voltages (behaving as an auto-transformer) (along with the neutral, of course).

Only problem there is that the fixture has to be on for there to be 120V.

I'm wondering if the camera can be had with a power supply that will operate on 277. With everything using switching power supplies today and being made for the world market that may be already a possibility.

-Hal

 

[hillbilly1]

One of the few times Solar would actually be more cost effective. Most cameras are dc.

 

[Joethemechanic]

One of the few times Solar would actually be more cost effective. Most cameras are dc.

Put the panel under the light and get free energy

 

[winnie]

Solar might be cheaper if the necessary receptacle, transformer, protection, to provide the 120V receptacles is high enough.

Not a question of free energy, just a question of total installation cost.

However I think post 6 is the key. Don't complicate the system by adding an extra conversion step. Find the voltage used by the camera and get a power supply that operates from the 277V input.

277V and 480V input DC supplies are commercially available.

Jon

 

[Joethemechanic]

Not a question of free energy, just a question of total installation cost.

He could put a motor coupled to a generator up there, if you hook the wires up right and use the right pulleys it'll run forever by it's self and power the camera too. It works kind of like this.

Shame big oil got to these guys and silenced them

 

[winnie]

We are not discussing perpetual motion scams, nor is anyone proposing one.

The OP has a question about supplying a very low power load at a location where the voltage is wrong.

The OP's proposal is reasonable, but has some issues.
1) A 120V receptacle fed by a 25VA transformer could only provide some 200mA at 120V. This might be sufficient for the camera but introduces the risk of someone plugging something else in.
2) Given the minimum size of available components, you are probably looking at a large box for the disconnect, combined with some pretty small fuses for the small transformer, then a box for the transformer, and then the receptacle.
3) Even if the continuous load for the camera is small, most power supplies have inrush current and the transformer selection needs to consider this.

@hbiss and I suggest sourcing camera power supplies designed to operate directly from 277V.

@hillbilly1 suggests that a solar powered camera might be cost effective. Not in some sort of perpetual motion sense; but simply the fact that a low power solar supply (including all of the necessary batteries and maintenance) might be cheaper than building the infrastructure to connect to the available 277V supply.

My hunch is that the long term reliability of a solar powered camera will be poor, but mostly because of battery issues. I'm assuming that the OP is powering wireless cameras, because if there are wires being pulled than POE or pulling 120V probably makes sense. Wireless is probably also going to be a reliability issue.

-Jon

 

[hillbilly1]

Solar might be cheaper if the necessary receptacle, transformer, protection, to provide the 120V receptacles is high enough.

Not a question of free energy, just a question of total installation cost.

However I think post 6 is the key. Don't complicate the system by adding an extra conversion step. Find the voltage used by the camera and get a power supply that operates from the 277V input.

277V and 480V input DC supplies are commercially available.

Jon

If 12 volt, all that would be needed is a small battery, along with a solar panel made for gate openers. Probably could do it for under $100 each. It would give 24 hr power instead of only at night.

 

[petersonra]

Hey guys, hope everyone is well. I'm scratching my head over this...

Let's say I have 277v site lights with 30 amp overcurrent protection and I want to install a 120v receptacle off of the 277v circuit. The receptacle is for cameras on the light poles. There will be one camera per light pole.

How would one go about achieving that?

I figure a disco with fuses going to a 25VA step down transformer.... then to a 15A GFCI receptacle... but this does not sound right.

Any advice is greatly appreciated.

You could do this.

I would see if I could find an assembly that was premade rather than making something myself though.

or maybe you could get a DC powered camera and put a DC power supply in a box and just skip the nuisance tripping of a GFCI. You can probably find a small power supply that can run off of 277 VAC.

 

[hillbilly1]

You could do this.

I would see if I could find an assembly that was premade rather than making something myself though.

or maybe you could get a DC powered camera and put a DC power supply in a box and just skip the nuisance tripping of a GFCI. You can probably find a small power supply that can run off of 277 VAC.

This is a pretty common problem, there is no doubt some manufacturer has produced a solution. $$$

 

[Todd0x1]

Are these cameras wireless or do they have a CAT6 cable going to them? What is the camera's power input? There are some power supplies out there which are fully encapsulated and take up to 300 something volts in and output 12vdc or whatever. Many are recognized component and not listed so make sure you check that. These are not expensive, <$100.

 

[Todd0x1]

Secondary requires a GES.

Wild: Auto-transformer?

Extra-wild: 120v tap on ballast?

He's talking about 25va, can't he use 250.30(A)(6) Exception 2?

 

[augie47]

Many large-format light ballasts have multi-voltage primaries. If you supply the 277v tap with 277v, the other taps will output their respective voltages (behaving as an auto-transformer) (along with the neutral, of course).

Granted, they're not designed to be used that way, but . . .

Been there.. done that... as you say, not design and perhaps Code questionable, but works

 

[hillbilly1]

Been there.. done that... as you say, not design and perhaps Code questionable, but works

Been done quite often, but now with auto-volt LED’s doesn’t work so well. LOL!

 

[augie47]

Been done quite often, but now with auto-volt LED’s doesn’t work so well. LOL!

Shows how long it's been since I did that