240v Lab Upgrade - Help Selecting Outlets - Page 1
Forum section: electronics / general

author: SGInut
author_rank: Contributor
timestamp: March 02, 2013, 09:07:42 pm
content: I am in the process of upgrading my lab to support 240V since a number of pieces of equipment I recently acquired use it, and I wish to get a nice reflow oven.Now comes the challenging part, which style outlets should I install. I know there are multiple world standards and being in the US I planned on using either NEMA 6-15 or L6-15, however I would like to start acquiring some more pieces of equipment and since it's a lot easier to get stuff from China, does it make sense to install a CPCS-CCC outlet as well? If I go that route, I was thinking of instead going with AS 3112 since I have seen them in a duplex configuration with dual switches (kinda prefer the extra safety) but will the CPCS-CCC plugs fit into an AS 3112 outlet?The other issue is frequency. 60hz is US standard for our 240v but from what I have read, it looks like 50hz is more likely what the items out of China would be expecting. Are there 60hz -> 50hz converters on the market that are worth it or does it not really matter that much? What about the 220v vs 240v (are 220v rated devices realisticly able to deal with 240v or am I chancing it too much?) Should I just install standard US NEMA outlets and use adapters? Thoughts?

author: mzzj
author_rank: Super Contributor
timestamp: March 02, 2013, 09:34:10 pm
content: Quote from: SGInut on March 02, 2013, 09:07:42 pmCant comment about outlets. But frequency difference is hardly any issue, no reason to convert 60 Hz to 50 Hz. Right now I can hardly think any sensible equipment that wouldn't work with 60 Hz as well. Some ac-powered clocks or clock-radios from seventies might go nuts as those may derive time from ac frequency, but this is hardly any issue with modern equipment.

author: IanB
author_rank: Super Contributor
timestamp: March 02, 2013, 09:41:28 pm
content: I installed a NEMA 6-20 socket to supply a 240 V electric kettle I brought over from England. It is simple, it complies with local standards, and it fits in the same receptacle box as a normal 120 V duplex socket.The 6-20 socket takes a 6-20 or a 6-15 plug. If the device doesn't already come with one of those plugs you have to cut off the existing plug and fit a new one, or maybe just use an appropriate IEC lead with the right plug on the end.

author: codeboy2k
author_rank: Super Contributor
timestamp: March 02, 2013, 11:53:08 pm
content: Like Ian, I too always installed Nema 6-20's in my shop. I preferred them over the 6-15 as they will take both 15A and 20A plugs.Make sure your circuit is sized for 20A though if you install 6-20 sockets. Otherwise what's the point?I also put in a few of the L6-20 locking sockets, I really like those at the ends of my extension cords or anything that is important enough that I don't want to be removed or fall out.As for the Chinese outlets, I don't think they would be UL approved, and so probably not a good idea to put them in, in case something happens. It would likely void your insurance.However, that said, the Wikipedia entry states that the Chinese CPCS-CCC plug and socket is the same geometric layout as the Australian AS 3112, but only 1mm longer plugs. It should fit. You would need to wire the socket according to what the Chinese device expected to see.Personally, I would not install that socket, but stick to UL approved sockets, and instead look for instruments with IEC plugs so you can change it out easily for a North American IEC to NEMA plug.

author: ejeffrey
author_rank: Super Contributor
timestamp: March 03, 2013, 07:41:35 am
content: I would definitely use standard NEMA 6 outlets and just change the plug on anything that comes with a foreign power cord.You will have to check with the manufacturer to see if the frequency and line voltage variation is a problem. You can fix the line voltage with a variac or transformer, but if the line frequency is a problem you need an inverter. Most things run fine. Even if they aren't intended to be international, equipment has to tolerate the normal variation of supply voltage. As for frequency, AC induction motors will run 20% faster, and usually with more power and higher efficiency. That may or may not be a problem.

author: G7PSK
author_rank: Super Contributor
timestamp: March 03, 2013, 01:56:13 pm
content: With induction motors or transformers you can usually get away with running 50HZ equipment at 60HZ but if you try it the other way around they will rapidly burn out. I know I have tried 60HZ motors on 50HZ and after a few hours the smoke comes out.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 03, 2013, 02:49:56 pm
content: On going from 60Hz to 50Hz, dropping the voltage to about 200V (with an autotransformer) will maintain the V/Hz ratio.

author: N2IXK
author_rank: Frequent Contributor
timestamp: March 03, 2013, 04:25:39 pm
content: Another vote for the 6-series NEMA devices. Installing anything else as part of permanent wiring is likely a building code violation, and can invalidate your property insurance.If you try to run a 50 Hz induction motor on 60 Hz, be aware that the speed will be higher than nameplate rating, even if you reduce voltage with a variac or whatever. In equipment like tape recorders or turntables, this can be a problem.

author: SGInut
author_rank: Contributor
timestamp: March 03, 2013, 06:39:08 pm
content: Thanks for the excellent feedback. I spoke with my homeowners insurance company and they actually have a person who deals with just this concern. Their guidance was to install a NEMA L6 outlet as the permanent hardwired outlet so it meets local building code then use a conversion cable/power strip with integrated circuit breaker and power switch to accommodate the other country specific plug. Apparently, as long as hardwired elements comply with local building codes and there is no sign of deliberately causing a fire, it would be covered. They just ask that caution be used and if the device does not conform to UL testing, it should be unplugged or switched off when not in use and to be present while the device is in use. That sounds fair (and sane) to me.The only items I have been looking to power are my air compressor (US spec), heat plate, and a reflow oven so I don't think the 60hz would be an issue based upon what folks have mentioned.