Member
kinda going off topic here...but im in the process of wiring up my garage to transform it into a shop. he told me i have 40 amps available, anymore and i would have to upgrade the whole panel. me, knowing next to nothing about electricity, is 40 amps enough for a small one man shop?
Member
40 amps at 120 volts can do a lot of woodworking, but if you are putting in new service, I would go for a lot more.
I have a small dust collector that draws 11 amps (minimum of 15 amp circuit) at 220 volts.
My combination machine draws 22 amps idling (30 amp circuit) at 220 volts, and a lot more when it is working
My big bandsaw is on a 30 amp 220 volt circuit, but pegs the ammeter for a long time during startup, and many have said it needs a 40 amp 240 volt circuit because of the starting current.
Then I have a number of machines that are designed for home use... they run ok on a 20 amp 120 volt circuit, nominally drawing under 15 amps ... Some would say each should have their own circuit. Forget that!
Small (14") bandsaw
Drum Sander
Air compressor
Turbine sprayer
Lathe
And a lot of other tools that draw under 10 amps.
Member
well i've got a big band saw, table saw, 5hp cyclone and planning on a jointer/planer combo, those are all 220, but only 2 running at any given time, like the dust collector and whatever else. its just that 40 amps doesnt SOUND like a lot of juice!
Originally Posted by Charlie Plesums
[OP]
Member
40A sounds too low to me. You'll need a 30A breaker just for the cyclone and you might want to have more than one machine running at one time. I often go back and forth between the bandsaw and jointer and just leave them both running. I suspect the more important question will be how many circuit breakers you have available as you generally like to have a separate circuit for each machine and 220V circuits take two slots each. My shop has a 100A subpanel with 32 slots and they are all used.
Greg
Contributor
I put in a sub box to serve my shop and used a 50 amp breaker in my main box to supply the sub box. Since I work alone, I almost never have two tools running at the same time so 50 amp has served me well.
Even if I left one machine running while using another one, that machine would not draw much current because it's just idling - no load. Tools only draw their rated current when they're working at capacity.
Mike
Last edited by Mike Henderson; 09-05-2007 at 6:33 PM.
Go into the world and do well. But more importantly, go into the world and do good.
[OP]
Member
Just for fun I measured the following idle currents:
3HP Tablesaw - 4.3A
1 1/2HP Jointer - 4.6A
16" Bandsaw (1" blade) - 11.6A
So I suppose it would be OK if you had only 40A.
Greg
Member
Unless you get into really big tools, yes. 40A is enough for about 8HP worth of motors running simultaneously.
Member
well now im considering upgrading the box to a 200 amp service. what would be a good number of amps to have for a shop anyways?
Member
Nick
I would check with your local utility to explore possible configurations I have had two houses with 400 amp service serviced by different utility companies,one ran 6 wires to the meter base which had six connection points and the other ran 3 and the service was split at that point to feed two 200 amp boxes. I am thinking from your post that your current service to the main panel is less than 200 amp. This would seem to be inadequate to feed both the residence and a fully equipped shop assuming thatat some point the house utilize a lot of the available power. I'm thinking that maybe an answer might be to leave the current service panel intact and have the utility run in a higher amp service and utilize a new service panel to feed the shop. Depends of course on the logistics of current service entrance in relation to the shop.
My current situation is somewhat different in that my shop is in a seperate building and I have a seperate service independent of the house. I used a 200amp panel simply because the cost of the panel was not signicantly different than a smaller 100 amp panel. I wired the building myself which is permitted in our area so I saved a substantial amount on cost.
Vern
Member
yes, our current service is at 100 amps, the electrician that was over suggested that we upgraded to 200 amps, which is exactly what we're doing. With that said, i'd send a 60 amp line to the shop, i think that sounds about right.
Member
If I were in your situation, I would put a 100 amp sub-panel in the shop. The extra cost of going from, say, 60 amps, to 100 amps is very small when you are doing the initial installation, but the cost of a later upgrade is huge.
How much do you "need"? I built a lot of furniture with a shop on two 20 amp 120 volt household circuits. But, as I have grown to larger equipment, in addition to the usual 120 volt outlets, I now have two 20 amp and two 30 amp 240 volt circuits (and one of those probably should be 40 amp) . I am drooling at a machine that requires a 50 amp circuit, and would require upgrading the dust collector (from 20 amps to at least 30 amps), and and and. So, even though I would have said 60 amps is plenty, if I had installed a 60 amp sub-panel, the potential new machine would require an expensive electrical upgrade.
Moderator
Nick,
If you're going to do it....upgrade the service on your house to 200 Amp service and run you a sub-panel to your shop with a 100 Amp service to it. What I've seen and heard others do before is run a minimal service to their shop because of what they had "right then" only to find out 2 years down the road that they grew some bigger tools that required a change of service from a 50 or 60 Amp to a 100 Amp service. It's more money up front, but the results are very long lasting.
Thanks & Happy Wood Chips,
Dennis -
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