Hey PM2000 Owners


Janello

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Mine is a sawstop 3HP, but I run it on 20A dedicated circuit no problem.  It's never tripped the breaker and I've pushed it pretty hard a few times.  I wouldn't waste your money on the bigger wire, especially if it's a long run from the box to the saw outlet.  

 

Also keep in mind that if the manual says 20A will cover it then you can rest assured that it will - you know how many lawyers probably read that manual before it was published?

 

Edit:  to be fair, the Sawstop manual says that the peak amp draw of my saw is 13amps, so I suppose I did upsize my circuit.  But I pretty much default to 20A circuits as a minimum anyway.  I would go with whatever the motor plate on the saw says.  If it's <= 20 then I'd go with 20.

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My 3HP 220V Jet Cabinet saw is on a 20 amp with no issues. I've pushed 8/4 walnut and cherry through there without tripping the breaker. There's the 80% rule with amperage. Your tool shouldn't exceed 80% of the breakers capacity, which would be 16amps. The PM2000 motor runs at 13amps

 

Here are the specs on the PM2000 3HP. 

 

   Motor Current (Amps) 13  

 

http://www.powermatic.com/Products.aspx?Part=1792000K

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==>especially if it's a long run from the box to the saw outlet.

Ahhhhh, no... Just the opposite... You up-gauge with long runs...

 

I forget my NEC, but there's a table showing at what amp/length you're required to up-gauge... I'm sure you can google it.

 

==>Motor Current (Amps) 13

3HP-220/1p is approx 12.6a draw. You put it on 20a for inrush. In some applications, 30a. TS would be 20a. If longer run, you up-gauge.

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==>especially if it's a long run from the box to the saw outlet.

Ahhhhh, no... Just the opposite... You up-gauge with long runs...

 

 

Right, exactly my point - the up-gauging is kind of irrelevant to what I was saying, though I admit I was less than clear.  My point is that if it's a long run and you're running a 20A circuit, you're up gauging to, say, 10/2 instead of 12/2.  If you were to run on a 30A circuit, you'd now be up gauging to (say) 8 gauge instead of 10 gauge.  

 

My point is that on a long run, doing a 30A  instead of a 20A means you're paying for heavier gauge wire, regardless of whether you're up gauging.  Either you're buying 10 instead of 12 or 8 instead of 10.  Either way you're paying a decent amount more for a (unnecessary IMO) higher amperage limit.

 

Of course, I respect the heck out of your knowledge and you've helped me out on electrical questions before, so please tell me if I'm off base here.  

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You should be fine following the code. Increasing the wire diameter adds a little peace of mind, but shouldn't be necessary under normal conditions.

As long as you aren't cutting corners on code.

If you run a machine that is wired to code and the cord becomes warm enough to notice, then your machine is drawing more current than you were told it would. Code defines how many amps are allowed through a conductor of a given size, not by the hp of the load at the end of the line. Any number of things can become abnormal and cause the load to draw more current while not actually producing more hp.

On longer runs, increasing the conductor diameter lowers its resistance to the flow of current. This is needed to avoid dropping voltage at the end of the line.

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==>Right, exactly my point - the up-gauging is kind of irrelevant to what I was saying

Sorry, I’m now more confused than before…

 

My intake of red wine at dinner is probably making me obtuse... So to clarify: loss occurs over distance. The more distance, the more loss… The more amps, the more loss… The thicker the wire, the less loss… The higher the voltage, the less loss… There’s also #phases, type of load, AC/DC, Al/Cu, inrush requirements, etc, etc, etc… Most standards accept a 2%, 3% or 5% drop in voltage – the rationale for the different thresholds is out of scope, but relate to type of load, potential equipment damage, fire hazard and some other factors (like efficiency)…  The math is straight forward – everyone learned it in high school physics, then never used again...

 

The NEC publishes a simple volts/amps/distance/gauge table. Easily Googled…

 

So, let’s take that 3HP PM2000… To simplify, let’s say 3HP, 220, 1p… Let’s round from 12.6a to 15a (the tables round up). Most tables will tell you to run 12g if the load is 50ft from the panel and up-gauge to 10/2 at around 100ft…

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==>Right, exactly my point - the up-gauging is kind of irrelevant to what I was saying

Sorry, I’m now more confused than before…

 

My intake of red wine at dinner is probably making me obtuse... So to clarify: loss occurs over distance. The more distance, the more loss… The more amps, the more loss… The thicker the wire, the less loss… The higher the voltage, the less loss… There’s also #phases, type of load, AC/DC, Al/Cu, inrush requirements, etc, etc, etc… Most standards accept a 2%, 3% or 5% drop in voltage – the rationale for the different thresholds is out of scope, but relate to type of load, potential equipment damage, fire hazard and some other factors (like efficiency)…  The math is straight forward – everyone learned it in high school physics, then never used again...

 

The NEC publishes a simple volts/amps/distance/gauge table. Easily Googled…

 

So, let’s take that 3HP PM2000… To simplify, let’s say 3HP, 220, 1p… Let’s round from 12.6a to 15a (the tables round up). Most tables will tell you to run 12g if the load is 50ft from the panel and up-gauge to 10/2 at around 100ft…

 

That explains it in a nutshell. My brain was still stuck on 30amps when I said I plan to run 10g. For the distance I am running, 12ga meets code for a 20A circuit.  

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==>Right, exactly my point - the up-gauging is kind of irrelevant to what I was saying

Sorry, I’m now more confused than before…

 

My intake of red wine at dinner is probably making me obtuse... So to clarify: loss occurs over distance. The more distance, the more loss… The more amps, the more loss… The thicker the wire, the less loss… The higher the voltage, the less loss… There’s also #phases, type of load, AC/DC, Al/Cu, inrush requirements, etc, etc, etc… Most standards accept a 2%, 3% or 5% drop in voltage – the rationale for the different thresholds is out of scope, but relate to type of load, potential equipment damage, fire hazard and some other factors (like efficiency)…  The math is straight forward – everyone learned it in high school physics, then never used again...

 

The NEC publishes a simple volts/amps/distance/gauge table. Easily Googled…

 

So, let’s take that 3HP PM2000… To simplify, let’s say 3HP, 220, 1p… Let’s round from 12.6a to 15a (the tables round up). Most tables will tell you to run 12g if the load is 50ft from the panel and up-gauge to 10/2 at around 100ft…

 

Let me try again :)

 

I think that you think I'm saying more than I actually am.  I'm making a very simple point:  just that upping the amperage of the circuit to 30A will be more costly, and it's an unnecessary cost.

 

Pretend for a moment that there's no such thing as line loss and that line length is irrelevant to distance.  (In other words, there's never a need to up-gauge).  All I was saying is that using a 30A circuit requires 10gauge, whereas a 20A requires 12gauge, which is cheaper.  The longer the run, the greater the difference in cost, obviously, because you're buying more of a wire that is more expensive.  That's all.

 

Even if you introduce line loss and Moore's law into the equation (pun intended), my point remains - if we have to up gauge everything, 8 gauge is more expensive than 10 gauge in the same way that 10 is more expensive than 12.  

 

In a nutshell:  a 30A circuit will be more expensive than a 20A circuit, so why do it if you don't have to?  That's my only point :)

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==>That's my only point

Now I get it... But unless we’re talking very long runs, the differential cost in wire is noise-level...

 

In most cases, it’s less expensive to up-gauge everything to the largest common capacity and purchase one large spool of wire rather than three smaller spools of differing gauge. Same goes for devices – a contractor 12-pack of a single NEMA configuration is cheaper than purchasing single units of 20a and 30a…

 

The biggest reason to up-gauge to the largest common capacity: if folks purchase new equipment and/or rearrange their shops (not an unheard-of phenomenon), then the risk of a new pull is reduced.

 

Summary: for short runs, cost should not be a huge factor when deciding to up-gauge. Cost can play a role in very long runs… Over the life of the shop, it may be less expensive to standardize branch capacity and leverage bulk purchases…

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==>That's my only point

Now I get it... But unless we’re talking very long runs, the differential cost in wire is noise-level...

 

In most cases, it’s less expensive to up-gauge everything to the largest something common capacity and purchase one large spool of wire rather than three smaller spools of differing gauge. Same goes for devices – a contractor 12-pack of a single NEMA configuration is cheaper than purchasing single units of 20a and 30a…

 

The biggest reason to up-gauge to the largest common capacity: if folks purchase new equipment and/or rearrange their shops (not an unheard-of phenomenon), then the risk of a new pull is reduced.

 

Summary: for short runs, cost should not be a huge factor when deciding to up-gauge. Cost can play a role in very long runs… Over the life of the shop, it may be less expensive to standardize branch capacity and leverage bulk purchases…

 

Thanks Trip - all great points.  I retract my cost concern and see your point about trying to look out for the future by up gauging everything now.

 

Carry on everyone  :)

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