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| Current draw for bench |
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| bterrier:
Hello everyone, Planning to install some power outlets in the wall behind my workbench. I am wondering how much current a bench power supply and test equipment will require. I am running approximately 6 outlets on a dedicated 15amp circuit. Is 15a enough for the entire bench or should I upgrade to 20? I still have half a roll of 15a wire, so it would be nice to use it, but if necessary I will upgrade to the 20a wire, breaker, and outlets. Keep in mind, I am a beginner and hobbyist. Sent from my iPad using Tapatalk |
| nanofrog:
This will depend on what you'll end up running simultaneously (total current draw on a given circuit). :-// For example in my case, the 120V circuits are 20A (old house, built in 1956). Granted, I've not tried to run every single item possible at the same time (no need to), I've never tripped the breaker. To put things into perspective, I've a window A/C unit that's always ON (say 10A IIRC as I live in a hot climate; i.e. 40C/104F these days :o) as well as all my computer stuff (likely another 2A or so). Yet despite all of this, running my oscilloscope, a couple of PSU's, and some other odds & ends, I still haven't managed to trip the breaker. So based on my experience, I wouldn't sweat it. Where this could be an issue, is if the circuit is shared by one or more current hogs (total sum is = or greater than 15A continuously). Hope this helps. :) BTW, if you go into your user profile and set your country, it's flag will be displayed beneath your userID. Makes it so much easier for other members to offer the most relevant information (i.e. pricing & availability; or in this case, mains voltage). |
| jpb:
As nanofrog has pointed out, current draw depends on the voltage. In the US or Japan current draw will be about double that in the UK or Europe for the same power. It also depends hugely on what equipment you use/can afford - ancient boat anchors have much higher power requirements than modern (but perhaps lower spec/ higher cost) kit. I've tended to restrict myself to more modern kit both for reasons of power and size but it does mean I've missed out on some ebay bargains. In my "lab" the highest current drawer is probably from linear power supplies which at say 30V 2A out probably draw 150W input. Otherwise it is my desktop workstation. For what its worth, I put my power requirements in this post: https://www.eevblog.com/forum/testgear/what-is-standardcommon-test-gear-dimensions/msg1599244/#msg1599244 My summary is as follows: Current loading. Total wattage of current equipment (assuming power supplies are 40% efficient) is 1072W which would require everything to be on at once. 13A at 240V is ~3kW. The workstation may be approximately 1 kW but can be plugged into a separate circuit. 1072W at 240V is approximately 4.5A so power strips that go up to 10A should be fine. |
| james_s:
It will be different for everyone, but if I turn on every piece of equipment on my bench and run the power supplies at full load it adds up to less than 1kW, so it's no problem to plug everything into a single shared circuit. If you're doing high power stuff your situation would be different but most modern (as in less than ~40 years old) test equipment doesn't draw very much power. |
| ArthurDent:
Having a dedicated run for your workbench does make it simpler. I rewired my old house with 12-2 with ground everywhere and the dedicated 120 volt run for the workbench has a high quality duplex 20A outlet with two 6 foot long industrial outlet strips with fuses, switch, protection, a lot of outlets, and a digital ammeter built into one end. I got these expensive outlet strips on Ebay for cheap because they weren't described that well and no one else bid on them. Some of the really cheap strips have outlets that will loosen up over time and may just use spring tension for ground contacts (not soldered) and can cause problems that are hard to pin down. Unlike the old tube-type frequency counter I had years ago that used neon bulb counting columns and ate up 600watt, My current counters (HP 53132A , Pendulum CNT-81) draw very modest power and most of the other equipment like GPS, frequency standards, DMM, scope, power supplies, etc., total 500-1000 watts if everything happened to be turned on and power supplies loaded. A 15A circuit would probably work just fine but if you only have 6 outlets I think you'll run out of outlets really fast and I would look into finding a good outlet strip or two with a total of around 24 outlets otherwise in the future you'll be adding computer style power strips to get what you need. |
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