based on on-site discussion and email suggestions.
initial document written tuesday, 20081007, 10 AM or so. I wiped out the original discussion and replaced with that below,20081026, 10 AM.
please add comments, do not delete any text you have not yourself written.
Workshop electrical upgrade is now done.
More to do:
THE LOFT: how to improve the electricity for the upstairs ("loft"?).
- how to get pipe up there: across ceiling and wall surfaces is best, minimize punching holes and trying to fish within walls.
- there may be an accessible branch point (at the j-box in the toilet room or in the subpanel itself) where it's possible to break the connection to the upstairs #14 receptacles, presenting the job of getting wires from the subpanel to that point.
- the loft has two circuits, #14 and #15. what power is required? issues are heavy loads and noisy loads. motors are both heavy (draw a lot of amps) and noisy (spikes and lows as motor turns off and on); heaters (hair dryers, hot plates...) are only heavy; some electronic devices can be noisy (return high-frequency waveforms into the line, often on the neutral return).
SO WHAT IS THE EXPECTED USE IN THE LOFT?
- The loft will have two large electric users -- soldering irons, and rackmount computers. I would expect a max of 5 200W soldering irons in use (call it 10 Amps), and a max of 10 machines at 200w each, or about 17 A. (Some of the machines will draw more but most will draw less.) We should verify the specs on the large UPS that's upstairs. There will also be misc users like lab gear, maybe another 5A to be generous. Adi 11:45, 7 October 2008 (PDT)
- NOTE: solder irons for electronics are 25W or 35W, so 5 of them on at once is about 2 A (rounded up). Mitch Altman 11:55, 7 October 2008 (PDT)
- this is my experience also. there are soldering guns and irons of 100W, but for electronic work they have only occasional use. --Jstockford 12:11, 7 October 2008 (PDT)
- if soldering is done upstairs, good chance people will be screwing around with electronic circuits, which presents the chance of inadvertent short circuits. probably good for electronicists to plug into fused receptacles, which could be little gizmos that plug into wall receptacles and present fused receptacles on the working side. i'd guess 5A would be plenty for most projects (including scopes, meters, soldering stations, circuits under test...). --Jstockford 12:11, 7 October 2008 (PDT)
- a dedicated 20A circuit is needed for the computer equipment. most 1U boxes suck 1A. it will be helpful to know
- the specs for the rack itself (how many units), four-post or two-post, shelves etc available?
- each machine (1U or 2U or what, and amperage for each).
so how to run the dedicated circuit? --Jstockford 12:28, 7 October 2008 (PDT)
OTHER: there are other possible useful projects:
- shannon clark in email raised a good point: task lighting for workstations. this applies not only to the electronic workstations in the loft but all workstations (in the fishbowl, chemistry, darkroom, computer stations...). a NOTE above suggests not letting a circuit power both lights and receptacles. as long as some light is lit when a breaker trips, safety concerns are okay. more receptacles can come from power strips or from adapters that plug into a duplex and present six receptacles. task lights should be considered in figuring circuit loads. --Jstockford 12:37, 7 October 2008 (PDT)
- isolated AC 110: get an isolation (1:1) transformer and put a receptacle on its secondary or get two identical step(down | up) transformers, hook one primary to AC, connect secondaries, hook a receptacle to the other primary winding.
- BENEFIT: isolated ground, reduced problems with noise and electrical shock hazard.
- UPS: probably good to have transformer isolation, but at any rate, make a circuit that charges a battery that can kick in to power an AC 110 emergency circuit, features can include some electronic notification of switchover and a warning of battery-too-low condition, even logging. more Amperage (i.e. more Watts) requires more money, lots more. --Jstockford 12:11, 7 October 2008 (PDT)
- complementary 12 VDC or other DC power system. could use uncomplicated battery backup to provide emergency power (lights, laptops). (there are 24VDC, 48VDC... (i like +12VDC with -12VDC dual tracking, but that's probably an audio-only approach).
- it might be nice to put some kind of spike/noise suppression on certain circuits, both to protect their devices from the clatter of other circuits as well as to prevent their clatter from bleeding out to other circuits. --Jstockford 12:28, 7 October 2008 (PDT)