Determining if Power Supply is Adequate

dusty · Post by **dusty** » Thu Jul 12, 2012 10:00 am

JPG40504 wrote:Had he read more, he would have 'discovered' that length of the wire involved is also a determinate of 'minimum' wire size.

In addition to protecting the structure from fire(overheating the wiring), the code is also concerned with proper voltage available at the far end of the circuit.

i.e. The 'inspector' is either ignorant, misinformed, an idiot, or most likely all three with control freak thrown in.

The proper size definition is more than a single chart, but involves several sections etc.

Without knowing all the facts (including specifics about the local code and actual installation) this might be a harsh evaluation. Sorta like management use to do to me without ever coming into my lab to see for themselves. "Management by Proxy"

fredsheldon · Post by **fredsheldon** » Thu Jul 12, 2012 10:49 am

Ok, I know nothing about electrical stuff. You guys have got me worried now. I just had a 120 20 amp and a 240 20 amp circuit installed in my garage. I have connected my SS to the 120 volt plug with a 15 foot 14 gauge extension cord. I will be connecting the SS to the 240 volt plug with another 15 foot 14 gauge extension cord that I have modified. Do I have anything to worry about and will I cause problems with my new PowerPro. Thanks in advance for any assurances you can provide

dusty · Post by **dusty** » Thu Jul 12, 2012 10:57 am

fredsheldon wrote:Ok, I know nothing about electrical stuff. You guys have got me worried now. I just had a 120 20 amp and a 240 20 amp circuit installed in my garage. I have connected my SS to the 120 volt plug with a 15 foot 14 gauge extension cord. I will be connecting the SS to the 240 volt plug with another 15 foot 4 gauge extension cord that I have modified. Do I have anything to worry about and will I cause problems with my new PowerPro. Thanks in advance for any assurances you can provide

If you are asking about the fifteen foot extension cords, you have absolutely nothing to be concerned about. The modified cord (to provide 240vac input) I cannot speak to. I know that some sort of 120/240 adapter has been used by others but I know no details.

As a test prompted by this thread, I connected my Mark V to 120VAC this morning via a 70' extension cord. It operated short term with no difficulty at all. If I was going to use it this way for an extended period of time (all day) I would be checking the cord regularly for excessive heat.

Ed in Tampa · Post by **Ed in Tampa** » Thu Jul 12, 2012 11:24 am

beeg wrote:Also some inspectors are knot happy with 12ga wire with a 15 amp breaker.

I met that inspector too.
Back in the 60's I built garage and did the wiring. I wanted Ground Fault breakers for the garage. My inspector came in asked what they were and promptly made me take them out. After he left I reinstalled them. Today they are mandatory. Go figure. Oh since I wired with 12 3 I also had to replace all my 15 amp breakers. Again after he left I reinstalled them.

Today they color code the wire so I had one inspector tell me I couldn't use yellow wire with 20 breakers. I asked why and he showed me in his book yellow wire must have 15 breakers. I asked if he knew what 15 and 20 meant. He smiled and said I needed to put another hold down on the wire near the box. Changed the subject. I did everything he wanted he green tagged me but the wiring was safer before the inspection than after it.

Ed in Tampa · Post by **Ed in Tampa** » Thu Jul 12, 2012 11:55 am

dusty wrote:I placed my comments in blue and within the quotes for ease of association.

Dusty in this post you said "If I understand what you are saying here, I disagree. The Shopsmith (any piece of electrical equipment) will only draw the amount of current that it will draw. It matters not if it is supplied by a 15 amp source, or a 20 amp source or a 60 amp source. If the supply line used in my video had been from a 60 amp breaker, the meters would good exactly as they do."

You are right a machine does not care if it has a 15 amp breaker or 60 amp breaker.

However Induction motors will try to maintain design RPMs regardless of load or voltage. An increase of load or a decrease in voltage will increase current draw and of course heat. If the wire feel very warm to the touch, then one or both factors exist.

Increasing or decreasing the length and/or gauge of wire from the plug to the machine will increase or decrease resistance. Resistance effects the voltage which then effect the amperage and if amperage goes up so does the heat factor.

So you are always better off using as short and as big a gauge of wire as is practical for your operation.

I personally prefer 12 gauge wire when it comes to my Shopsmith. I have proven to myself that my machine runs far better when I supply electricity to it via 12 gauge wire.

In fact all my extension cords are 12 or bigger and if I'm using a motor and it starts to get hot I move up to the next size bigger wire. I have never burned up a motor.

Ed in Tampa · Post by **Ed in Tampa** » Thu Jul 12, 2012 12:00 pm

fredsheldon wrote:Ok, I know nothing about electrical stuff. You guys have got me worried now. I just had a 120 20 amp and a 240 20 amp circuit installed in my garage. I have connected my SS to the 120 volt plug with a 15 foot 14 gauge extension cord. I will be connecting the SS to the 240 volt plug with another 15 foot 4 gauge extension cord that I have modified. Do I have anything to worry about and will I cause problems with my new PowerPro. Thanks in advance for any assurances you can provide

I hope the 4 gauge is a typo for 14.

4 gauge on 240 would be total overkill.

14 on 240 is better than 14 on 120 and yes you should be just fine.

dusty · Post by **dusty** » Thu Jul 12, 2012 1:01 pm

Ed in Tampa wrote:I hope the 4 gauge is a typo for 14. 4 gauge on 240 would be total overkill.

14 on 240 is better than 14 on 120 and yes you should be just fine.

With what size breaker? If the 240 has a 20amp breaker, I'd bet code requires 12ga.

fredsheldon · Post by **fredsheldon** » Thu Jul 12, 2012 1:11 pm

dusty wrote:With what size breaker? If the 240 has a 20amp breaker, I'd bet code requires 12ga.

What gauge is the standard power cord that came with the PP upgrade. Should the 15 foot extension be the same gauge.

Ed in Tampa · Post by **Ed in Tampa** » Thu Jul 12, 2012 1:16 pm

dusty wrote:With what size breaker? If the 240 has a 20amp breaker, I'd bet code requires 12ga.

He was talking about an extension cord. I said running his Shopsmith on 240 volts with a 14 gauge extension he should be fine.

I'm not sure what size wire you would have to run to pull 20 amps on 240.
That is 5.8 kw and I'm guessing you would probably have to go 8 or 10 gauge but I don't know.

dusty · Post by **dusty** » Thu Jul 12, 2012 1:25 pm

Ed in Tampa wrote:He was talking about an extension cord. I said running his Shopsmith on 240 volts with a 14 gauge extension he should be fine.

I'm not sure what size wire you would have to run to pull 20 amps on 240.
That is 5.8 kw and I'm guessing you would probably have to go 8 or 10 gauge but I don't know.

Current wise, I agree. The Power Pro draws less current on each leg when operating on 240 than it does when operating 120.

However, does building code play into this discussion?