[TheForge] Light bulbs and shop power
Ed Eccleston
edeccleston at att.net
Fri Aug 3 11:10:39 EDT 2012
Hi all,
New to the site and a wanna be blacksmith, but I'm a General Contractor
in Ca. and deal with such electrical matters periodically. In no particular
order...the electrical design and requirements are based on anticipated
load. The Electrical Code has specific wire sizing requirements based on
the amperage (which is the actual current draw.) For example, most
residential wiring for basic wall receptacles will run from a 110v. 20 amp
circuit breaker in the panel. Electric dryers and larger A/C units will
require 220v. (which is achieved by having a wire carrying 110v. from each
side of a 220v. panel. The two large gauge wires that come into the house
from the pole each carry 110v. When you measure the voltage across those
wires, you get the 220v. potential.) When you turn something on, it
determines what it needs to operate. A motor that requires 30 amps has no
clue that it is being "fed" through a 20 amp breaker. The breaker is the
safety valve, because the wire size will have been determined based on the
20 amp breaker during construction, which is #12 size. Rule of thumb is:
15amp breaker requires minimum #14 ga. wire...20amp= #12
ga....30amp=#10ga....40amp=#8ga....
The length of the run is not so critical as long as the wire size is
sufficient. It's when you have a combination of long run, small wire size
and larger draw that you get into hot water. (Sorry, mixing metaphors).
And yes, the result of such a mix is heat. Think of how an in line buss
fuse works. A thin piece of metal conducting current. When the current is
more than it can handle, it melts.
So the fire hazard is real, and the problems more often than not occur at a
connection. Bruce is absolutely correct. As you all know, metal will
expand and contract with temperature. That little #12 wire attached to the
receptacle in the wall, often by being wrapped around a screw on the side of
the receptacle, over your kitchen counter where you have plugged your coffee
pot into for 22 years...... that wire has expanded and contracted every time
you turned the pot on and off. I absolutely guarantee that the large
majority of us could check those connections and find them loose. The screw
ultimately loosens a bit through the years. And anyone who arc welds knows
how a small gap between electricity and its intended (or unintended) path
can have spectacular results! Oh, and when an arc occurs, no matter how
infinitesmal, you'll get a carbon buildup which is an insulator, which means
the conductivity is more impaired, increasing resistance and therefore heat.
Anyone who's cleaned the battery posts on the truck and then all is well
again knows the benefit of good, clean, tight connections.
Back to the problem at hand. The ideal circumstance is to have a
sub-panel at your shop with sufficient capacity to add what gadgets you may
want down the line. The concept of actually having a meter there could be a
tax advantage, but I don't know THAT code very well. Ron, your #6 wire is
code for 50 amps, which will run a large buzz box along with most other
things in a shop with ease.
The 100' run of probably basic house Romex wire that is powering your
friend's shop is fine for lights, but the big draw of the motor is asking
way too much of the system. And the lights dimming tell me that the circuit
breaker is not just dedicated to the shop line. I'll bet that when the
breaker pops, something's not working in the house, also. Oh, and final
note, generally the more that a breaker pops, it gets weaker.
Yes, it's not inexpensive to get set up properly, but it's sure a lot
safer.
Thanks for letting me blather.
Ed Eccleston
P.S. Noticed a bunch of chiming in happening while I was slowly typing.
Sorry for redundancy.
----- Original Message -----
From: "Bruce ." <freemab222 at gmail.com>
To: "Blacksmithing List Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Friday, August 03, 2012 7:02 AM
Subject: Re: [TheForge] Light bulbs and shop power
> Well, the "hours at a time" part precludes the simple suggestion I made.
>
> I'm no electrician, but I think the answer to your question is 'no.'
> I believe to be legal (and safe) the wires must be in electrical
> contact their entire length. I could be wrong about that. But I have
> given the same thing some thought, simply because of the availability
> of smaller-gauge wire on the cheap. This is not to say that it
> wouldn't work -- it probably would -- just that there might be some
> serious gotchas involved.
>
> If an electrician is lurking, a comment from him would be useful.
>
> Maybe the first thing to do is to inspect the connections through this
> shop circuit. Possibly there are some flawed connections -- loose,
> corroded, burned, etc -- which, if fixed, might fix the problem.
>
> I've seen (via photos, not in person) a burned connection on one of
> the three hot lines coming into the building I was working in. This
> was discovered only after months of problems at the lab bench
> (computerized instruments behaving badly), which eventually were
> attributed to power dips. Fixing the burned connection (burned due to
> arcing, probably, due in turn to a loose connection) seemed to fix the
> problems experienced at the bench. (The company probably wasted
> hundreds of thousands of dollars in bad results before the input box
> was examined.)
>
> On Fri, Aug 3, 2012 at 9:36 AM, Ron Childers <ron at munlaw.net> wrote:
>> He grinds with a 1h/p 2x72 for hours at a time. Would it be
>> practical/safe to just run another cable of the same or larger size in
>> parallel wired together at the terminals? If it is #12 then another #12
>> should at least double the capacity. I think there is a formula for
>> that...
>>
>> -----Original Message-----
>> From: theforge-bounces at mailman.qth.net
>> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Bruce .
>> Sent: Friday, August 03, 2012 8:42 AM
>> To: Blacksmithing List Sponsored by ABANA
>> Subject: Re: [TheForge] Light bulbs and shop power
>>
>> Find out what gauge wires run between house and shop, and look up to see
>> what gauge should be used over that distance. I would guess they should
>> be at least 10-gauge. Possibly somebody ran only 20-gauge (which may
>> suffice for lights).
>>
>> Copper is expensive. I wonder whether there might be a work-around if
>> the heavy load is only used occasionally. Like, maybe, charge a car
>> battery in the shop, then run the 12V through an inverter to power the
>> grinder. This wouldn't make sense for running machines all day, but if
>> it's a few minutes now, a few minutes later it might save a lot of money
>> on copper and electrical inspections.
>>
>> On Fri, Aug 3, 2012 at 7:47 AM, Ron Childers <ron at munlaw.net> wrote:
>> <snip>
>>>
>>> Back on topic: The shop lights go very dim every time a friend turns
>>> on a grinder in his shop which is over 100 feet from the house. The
>>> wiring to the shop is fed from the house and there is no drop box. My
>>> guess is the wire is too small to carry the load that far. If someone
>>> honks down on the abrasive cut-off saw it trips a breaker in the
>>> house. It is an electrician's nightmare that was there when he bought
>>> the house and so far is only annoying, but does anyone know of this
>>> kind of situation causing a fire? I think it needs heavier copper wire
>> and a drop box.
>>> Also, I don't know the amperage of the breaker. I used #6 and don't
>>> have that situation. I feel a bit uneasy about this but need to
>>> justify my concerns before beating him up about it. Does anyone have
>>> some words of wisdom? Thanx, Ron
>>>
>>>
>>> -----Original Message-----
>>> From: theforge-bounces at mailman.qth.net
>>> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Jerry Frost
>>> Sent: Thursday, August 02, 2012 9:32 PM
>>> To: Blacksmithing List Sponsored by ABANA
>>> Subject: Re: [TheForge] TheForge Digest, Vol 102, Issue 14
>>>
>>> Simple logic, zero. They hold nothing; vacuum.
>>>
>>> Jer
>>> ----- Original Message -----
>>> From: "Ron Childers" <ron at munlaw.net>
>>> To: "Blacksmithing List Sponsored by ABANA" <theforge at mailman.qth.net>
>>> Sent: Tuesday, July 31, 2012 10:34 AM
>>> Subject: Re: [TheForge] TheForge Digest, Vol 102, Issue 14
>>>
>>>
>>>> How would you compute the volume of a light bulb? (-:\>
>>>>
>>>> -----Original Message-----
>>>> From: theforge-bounces at mailman.qth.net
>>>> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of Andy Gladish
>>>> Sent: Tuesday, July 31, 2012 1:43 PM
>>>> To: theforge at mailman.qth.net
>>>> Subject: Re: [TheForge] TheForge Digest, Vol 102, Issue 14
>>>>
>>>> Thanks! I figured this one (a different way involving a lot of
>>> geometry-
>>>> I'm going to use your method!) out at 3:30 this morning, lying awake-
>>
>>>> it's always wierd how simple the solutions are once you get them...
>>>> Andy G.
>>>>
>>>>
>>>>>
>>>>> Message: 2
>>>>> Date: Mon, 30 Jul 2012 15:29:33 -0400
>>>>> From: "Ron Childers" <ron at munlaw.net>
>>>>>
>>>>>
>>>>> 1/2" pipe or square for the pattern....Bend to shape then lay out on
>>
>>>>> the shop floor and duplicate. Try it for fit before final welding.
>>>>> Jeff and crew did one and it was a real treat getting it up to the
>>> 3rd
>>>>
>>>>> story through a narrow staircase after the wall was painted and the
>>>>> hardwood floor was varnished. It fit; billowed curves and all, yea!
>>>>> The owner's wife caught us in the act of final fitting and she loved
>>
>>>>> it..Compliments on the work, husband paid the price and the check
>>>>> didn't bounce. Fitting on an outdoor railing should be easier but it
>>>> must adhere to specs...
>>>>>
>>>>>
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>>>>
>>>>
>>>>
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>>
>>
>>
>> --
>> Bruce
>> NJ
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>
>
>
> --
> Bruce
> NJ
> ______________________________________________________________
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