PM66 Owners


Just ordered one. Reading through the owners manual I was struck by the electrical diagrams calling for 10Ga wire and a 30Amp (220V) circuit for the 3hp 1phase motor. Years ago (in anticipation of ordering the saw) I installed a 20A 220V line to my saw -- it was my understanding that a 20A 220V circuit was plenty of power for a 3HP motor. Is the 30A designation in the manual just a typo ?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'm surprised at the recommendation. Dedicated 20 amp service should be fine. I bet the cord on the saw is smaller than 10Ga. !
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

heater is #12. #12 can handle more than 20a, but anything over 20a requires a 30a breaker, and a 30a breaker requires #10. Then there is the issue of voltage drop; cords are shorter than your house wiring. It is best to follow their recommendation. Perhaps the voltage drop is excessive on #12 when starting, leading to shorter life. Or maybe they have a reason I haven't thought of.
(Now, the circuit to my water heater had been #12 on a 30a breaker for 35 years until I noticed and replaced it last year; and the house didn't burn down. But that doesn't make it safe or legal. And it is not a motor; a water heater doesn't really care about voltage drop.)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I would have to agree with Woody. I always think of voltage drop as the run gets longer. I think this every time I wire up a machine straight from the panel with say 10gauge to say a welder and then connect it to the 14gauge wire inside the welder. I always say to myself "I spent three times more for 10ga because of the voltage drop???"
Never fully understood why, but I always think that the electrical code and UL approval have two different ideas on electricity (i.e. electrical code says you need 10ga to the machine, UL says you need to run 14ga in the machine).
On the other hand I think the cooper manufactures "influence" the electrical code in a mafia like style, and maybe, just maybe that have not infiltrated the UL yet.
Of course I am wrong on all fronts.
Chris

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Plus, if you experience a voltage drop (due to inadequate wiring gauge) you will generate heat in your house wiring...heat + combustible materials = wish I'd spent the extra $100.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I have my 3HP 66 on 20 breakers never had a problem. The run from my panel to the outlet was bout 30 feet for that reason and in case I needed to go to 30 I ran 10AWG. Joe
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sam the Cat wrote:

What's the actual motor plate rating and starting inrush?
If it's a dedicated circuit or only one item is run on the circuit at one time it will undoubtedly serve as I'd assume you have a pretty short run.
I wired the shop w/ 10AWG and 30A breakers just on general principles. The PM66 I have is nearly 30 yrs since I bought it so I have no recollection any more of what was suggested but I'd have run 10AWG irregardless just on general principles...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I would absolutely contact their customer support people before spending money on breakers or wiring.
http://www.powermatic.com/support/support.htm
I purchased a 54A jointer a year or so ago. While setting it up I noticed some areas where the manual and the jointer were at odds. After setup I walked through the book and compared it with the features the manual described. There were problems - some glaring. Powermatic finally admitted they had some problems with the 54A manual.
If it can happen once it will happen again.
RonB
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Just got off the phone with Powermatic Tech support -- they acknowledge that a 20 Amp should do but that the saw draws 17A when running and can double that at startup. Given this they _recommend_ the 30Amp breaker to avoid problems in the future. Evidently if the current fails to support the motor at startup it can damage the motor.
Now to knock the rust out of my brain I was under the impression that a single phase 20Amp circuit could supply 20Amp but that a 220V circuit could source 20Amp on each phase -- thus providing an effective 40 Amp rating -- was I dreaming ?
Guess I know what I have been saving that coil of 10Ga Cable for..........

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sam the Cat wrote:

their saw. I ended up with a Unisaw 3HP. It runs off of a 220 line I installed with 20 amp breakers. It shares the line with a compressor. It has NEVER kicked off the breaker (3+ years usage). AND, I don't believe that Delta even suggests that a 30A breaker is needed to use their 3HP Unisaw. Someone correct me if that's wrong.
Dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Sam the Cat wrote:

240V is <still> a single phase...only thing different is the second leg isn't at neutral, it's at the opposite polarity of the other. The total current still flows through the two conductors so they're rated same as 110V.
You can still most likely get by, the recommendation is surely conservative, but what do you expect from the vendor? They've got to consider any installation where there may be a long run (hence, voltage drop) from the supply panel....
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

17A would be full load current, which is rarely ever reached unless you are ripping 3" very hard wood. I would venture to say you won't even get to half load ripping anything less than 5/4. The initial current (starting inrush is for a very, very short time on a table saw, because you are only have the inertia of spinning up the blade to overcome. The circuit breaker characteristics are such that it tolerates short term high current without tripping. Voltage drop is not really a factor for short runs.
But this is all academic. There's nothing wrong with the conservative approach of going with the 10 ga.
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
my powermatic 65 (1ph 3hp) is on a 15 amp dedicated breaker with 10g wire. never popped the breaker once.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have my 1ph-5hp-PM66 on a 20 amp dedicated w/ 10ga wire to the outlet. IIRC after getting the saw setup, I checked the amp draw at startup and got 18amp reading. Also, IIRC I saw 15amp while running.
YMMV
I've not had any problem with this setup. I was comfortable with the 20amp service to the saw after doing some study and research on the same issue while I was waiting for my saw to arrive.
However, this is your baby (and your home or shop). You would certainly be on the safe side with 30amp. I would not scrimp on the wiring ... do 10ga.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I got the wire and upgrading the run will only take an hour or so to replace -- its all exposed wiring -- I think I'll go with the 10Ga...

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 19 Aug 2005 06:06:16 -0400, "Sam the Cat"

Twenty amps is plenty for a 3HP motor.
P"0*30D00 volt-amps
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.