Would you Run a 230V Air Conditioner @ 208?

ndzied1

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Aug 2002
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Chicago, Illinois
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I have a customer w/ 208VAC service that wants to add an air conditioner to an enclosure.

I can supply a 230VAC unit with a +/-10% rating on the input voltage for a minimum rated allowable input of 207V.

This is actually for the customer of my customer. We have run the thermals on the enclosure and it will not need any cooling but the end customer has specified that they want an A/C unit anyway. Bottom line is this thing will probably not run a lot.

What are your thoughts.
 
It will most likely run okay. The current will be higher than the nameplate rating on the unit. Specify that they must use one size larger wire (if the circuit is longer than 50 feet). Also, ask for an actual voltage reading. Often in these cases I bump the transformer up to a higher voltage tap, so that the voltage is actually 218/126 volts. Sometimes the voltage runs high anyway. Get a reading (and a feel for the situation) before you make any committments.
 
I personally would use a buck-boost transformer. That is what these were made for. Google it and you should have all the information you need.
 
Hi Norm,

I would consult the nameplate-rating of the equipment. It should specify 208/230, if it is newer equipment, which means it is designed for either voltage. Some of the older stuff is strictly one or the other.

Say! Do you have any relatives in the Detroit area? I have worked with more than one Dziedzic throughout the years.

Good Luck,

NJG
 
The +/- 10% should be the same as 208/230. Since there have been numerous commercial facilities in the US that have 208vac most things are designed to use it but if you want to be "safe" then use the transformer bruce mentioned.
 
NJG, Norm already said HE is supplying the air conditioner and it is rated for 230 volts only.

Bruce, if Norm adds a transformer to his price, it will most likely mean he will not get the order.

Norm, some customers cause more problems than others. Some of them are independent and serve-yourself types that can handle small problems with their own solutions. Others expect the supplier to jump at their every whim. Which type is this?

I have installed a lot of 230 volt equipment on 208 volt circuits, things like vent fans, heaters, louvers, door openers. But I avoid doing this on equipment that requires high starting current, such as air compressors, and HVAC compressor units.

Can you get a current curve for this enclosure cooling unit? Is the starting current at 208 volts high enough to cause an overload trip?

Probably if 208 volts is available, then 480 and 120 volts are available at this customer site also. Those are the ones I normally use in a new US plant.
 
Last edited:
Thanks for all the replies.

The unit is only rated for 230, not 208/230.

As I said, my customer is the OEM. The customer actually buying the machine has only 208 service into the building.

The machine is somewhat of a standard so the end customer is installing a 208 to 460 Transformer to power the entire machine. Remember, the standard machine does not require cooling. The end customer has asked for this specifically even though the OEM who designs these all day long says it's not required.

Anyway, I said they could try to hook it up on the 208 but that I wouldn't guarantee it would work and they would have to add their own disconnect to it.

I recommended they get a 430 to 230 transformer wired after the main disconnect.

And, as always, since I'm at a distributor, I work with the products we have from our suppliers. Rittal does not make a small 460 wall mount air conditioner. The smallest 460 air conditioner is 3 times larger and since we don't feel we need any cooling, the smallest and least expensive is where we're going.

Just for those wondering, at 230, single phase, the A/C unit is speced for 1.3A running current and 4.4A inrush current.
 
ndzied1 said:
Thanks for all the replies.

The unit is only rated for 230, not 208/230.

As I said, my customer is the OEM. The customer actually buying the machine has only 208 service into the building.

The machine is somewhat of a standard so the end customer is installing a 208 to 460 Transformer to power the entire machine. Remember, the standard machine does not require cooling. The end customer has asked for this specifically even though the OEM who designs these all day long says it's not required.

Anyway, I said they could try to hook it up on the 208 but that I wouldn't guarantee it would work and they would have to add their own disconnect to it.

I recommended they get a 430 to 230 transformer wired after the main disconnect.

And, as always, since I'm at a distributor, I work with the products we have from our suppliers. Rittal does not make a small 460 wall mount air conditioner. The smallest 460 air conditioner is 3 times larger and since we don't feel we need any cooling, the smallest and least expensive is where we're going.

Just for those wondering, at 230, single phase, the A/C unit is speced for 1.3A running current and 4.4A inrush current.

Norm
based on run current the unit sounds like a 1/2 ton unit at most probably 1/4 ton. You should be able to get one that will run on 120 VAC line. Any other comments I would make have already been stated.

Dan Bentler
 
If a boost transformer is needed, a 50-100VA control transformer set up as an autoformer would be enough. 208v or 120/240v primary, 24V secondary. Remember, with an autoformer, you rate it based on the secondary current.
Should be a cheap and easy solution.
 
leitmotif said:
Norm
based on run current the unit sounds like a 1/2 ton unit at most probably 1/4 ton. You should be able to get one that will run on 120 VAC line. Any other comments I would make have already been stated.

Dan Bentler

GEEZ, did not think about this, Norm said it was for an enclosure (I assume panel by that). A 5000 BTU unit (which is 120 normally) would be OVERKILL.

208vac 3 phase definetly has 120vac 1 phase, you telling me you have nothing along those lines for an enclosure?
 
Guys,

All good points. Welcome to my world. I get asked questions but am usually given little information. So, do I assume what the customer has or just go with what I have been asked?

I was asked if the 230 A/C unit could run on 208. Checked the specs, found the +/- 10%. Then they ask what the transformer would be to run the same 230 A/C unit from the 460 they are making on the large transformer.

The 120V option sounds good so I'll propose that as well...
 
Norm check to see if they brought the neut into the cabinet -- if so you should be OK to run 120V AC unit. If they did not (very common on our machines) then you have a snag.

Why oh why are they so cheap to save on cost of one conductor when it would make life oh so easy I will never know or understand.

Guess I should be grateful they spent all them big bucks to pull in a ground conductor.

Dan Bentler
 

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