How to Monitor 120V/20A (NEMA 5-20P) Lab Equipment With 220V/20A Power Meters?

Hi! 


I'm not sure how to properly ask this question - here goes. I bought two devices to monitor power usage in our labs - one is rated for 220V/20AMP eqeuipment (and has NEMA 6-20P plugs) and the other is for 120V/15AMP, and has standard NEMA 5-15P. 
www.bosscontrols.com for more info


The issue is, a lot of our lab equipment is designed to run on 110 circuits but pull 20 amps, and they therefore have NEMA 5-20P plugs. The outlets in our labs are usually rated/designed to have 20AMPS, so this isn't an issue, but now I'm wondering what the best way would be to be able to use these plugs to monitor the 120v/20a stuff. Obviously placing the smaller 110/15 amp between the equipment and the outlet would fry it unless I can step down Amps, which would likely cause the equipment to malfunction.


Therefore it seems I could use some sort of transformer to step down the voltage of the 220V/20A measuring device, but I can't seem to find them that are affordable and easy. Any standard travel transformer, for example, is only rated to around 5 amps. 


Any thoughts? 


Thanks so much in advance! 


Jen

Jennifer - OK first question - do your individual equipments pull 20A (what ARE they??!!) , or do you just have a 20A circuit (ie the circuit can supply a total of 20A to multiple outlets before it trips)?If you have individual equipments pulling 20A on a 110V circuit then yes you appear to have a problem.
It's quite possible that the 220V device will actually function on 110V but the specifications don't include this info.As a first step I would contact Boss and talk to one of their tech staff and see what they say.  They seem keen to help - on one PDF I found thisLet’s get started today. Call us at 412.961.8500 or Toll Free at 855.708.4990
For more information: info(_at_)bosscontrols.com | www.bosscontrols.comSo give them a call and see what they can offer.  It sounds like you have quite a bit of equipment there, so if you will eventually buy a few of these then Boss may do a special order for you.The other thing you can do is have someone make up some adapters to use the sockets with your plugs.  Warning - this may not be legal though.So talk to Boss first, usually a vendor will be keen to help you.Lastly, you say you want to monitor power usage, the Boss devices do a lot more than that, have you looked at simpler alternatives? 

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Hi David! Thanks for the detailed reply.To be clear, I've definitely been talking with Boss a lot, but their somewhat political (and understandable) response is that I shouldn't be adapting or transforming these at all.In terms of the equipment types, obviously some 110V things that I'll be monitoring are only pulling 15amp even thought they're on standard 20A lab circuits, however, some equipment such as medium size ovens are designed to plug into the 110V outlets but are (ostensibly) pulling up to the full 20A. Therefore they have the NEMA 5-20p plugs and wont fit into the BOSS 110 devices.I do want all the functionality of the BOSS devices - we use something similar but "hacked" already in a lot of MIT labs, and I'm looking to roll out a more systematic program for monitoring - and turning off- certain lab plug loads.
So again really my question (as I am not an electronics expert) is whether it is possible, albeit maybe not recommended for long term, to use a transformer or something else in order to make use of the 220V/20A BOSS plugs for a 110V/20A device?

Jennifer I am always hesitant to offer advice when someone is working with voltages/currents that can kill you. Before you follow anyone's suggestion I insist that you get someone who can advise you as to safety and the law.You can do what you want with an isolated or auto-transformer, but you probably will not get any outlet types that you need. You will have to wire them yourselves.Your input requirement is a 250V 20A device which is 5000VA. There are  5000VA transformers and because transformers work on the principle of power in=power out, you will have the added benefit of  110V at 40A (with an adjustment for efficiency)..I am not sure where you are located, but if you search on Digikey and filter is down one remains.Your consultant will have to figure out how to wire it..Take great care.

Jennifer sorry, I should have looked more at the transformer angle.If you have a 110V 20A source you can put in a 110-220V transformer which will then give (approximately) 220V at a maximum of 10A.  You then put your Boss 220V 20A goodie in the circuit, then you get another 220-110 transformer (same thing but wired the other way round) to get it back to 110V.  So far so good, BUT:- Transformers are not 100% efficient, you will lose around 5-10% over two transformers I would think.  At the powers you are dealing with that's about 200W. You can of course compensate for this in your readings and calculations if you can measure it.- A 2KW 110-220V transformer is going to be a big, heavy beast (like a cubic foot and 50 pounds plus). If you just need one it is maybe feasible, but if you need these devices all over your lab you are looking at a lot of space, weight and cost. As you say, not affordable or easy. (PS - note - looking at Aubrey's link below, make that 150 lb!)- As you're working with dangerous voltages here, I assume you would need to get a qualified electrician to wire them for you (you would in Australia where I am)So I would probably agree with Boss that you shouldn't be transforming the source. But adapting is another matter.I'm surprised Boss are not more cooperative, especially if you're eventually looking at a lab full of these devices.  I don't think it would take much modification to get one of these devices doing what you want, or something near it.  Ideas...- modify the 220V device to work on 110 v at the same 20A max current (even if you have to apply a correction to get the right measurements)- Modify the  110V device to work up to 20A (they'd have the components available already in the 220V ones)- supply the existing standard devices with flying leads and plugs and sockets to cope with your lab (but this does not address the 110V 20A requirement)Have you looked at other manufacturers?  You may not find one who has exactly what you want, but you may find one who is more amenable to mod their devices to fit your requirements.If you have an engineering department near you (I'm assuming you're at or allied to a university somewhere) enlist their help to come up with a solution for you.So near and yet so far, you do have a thorny problem.

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Excellent thread..!!!

Jennifer
 I am always hesitant to offer advice when someone is working with voltages/currents that can kill you. Before you follow anyone's suggestion I insist that you get someone who can advise you as to safety and the law.
You can do what you want with an isolated or auto-transformer, but you probably will not get any outlet types that you need. You will have to wire them yourselves.
Your input requirement is a 250V 20A device which is 5000VA. There are  5000VA transformers and because transformers work on the principle of power in=power out, you will have the added benefit of  110V at 40A (with an adjustment for efficiency)..
I am not sure where you are located, but if you search on Digikey and filter is down one remains.
Your consultant will have to figure out how to wire it..
Take great care.See Good Answer I Wote On This Answer It up online-surveys.info