Code vs. Common sense. A disconnect question.

[NoShopSkills]

When I moved my lathe into it's permanent location (on a wall under, tucked in under stairs) I opted for two pieces of safety equipment. First was a guarded motor starter, combined with a big, easy to find paddle style emergency style stop. https://www.grizzly.com/products/H8242

The next thing I did was pick up an industrial quality disconnect box with a similarly big, easy to reach lever style throw. The power from the main breaker box routes through the wall, into the disconnect located at the tailstock end of the lathe and then via armored cable to the paddle style switch. then on to the motor.

Since I'm a one man shop hobbyist and only plan on running one machine at a time, is it totaly unacceptable to use a second knock out and a second armored cable from the same disconnect to power up my mill? I plan to set the mill in the middle of the garage floor. My other option would be to bring power down from the ceiling and have a 2nd, dedicated disconnect on either the milling machine itself, or a free standing pedestal built solely for the purpose of being a place to mount the disconnect.

 

[twstoerzinger]

I know that there are some NEC (National Electrical Code) experts on the forum. They may jump in and quote chapter and paragraph, but let me see if I can summarize the intent of NEC when it comes to disconnects.

The idea of the requirement for a disconnect is to allow you to do maintenance (mechanical or electrical) while knowing that the power is removed and cannot be accidentally re-applied by you or someone else. There are two considerations: "in sight" and "out of sight." (The code probably uses some fancier words).

"In sight" means that you can readily observe the disconnect while you are working - and know that no one will walk up to it and energize it. In this case, a lockable disconnect is not required. Note that a typical plug can serve as a legal disconnect for this case simply by pulling the plug and leaving it on the floor.

"Out of sight" means that the disconnect is far enough away or out of sight such that you cannot be sure that someone will not walk up and turn it on. In this case a lockable disconnect is required. Most manual disconnects have a means to apply a padlock to meet this requirement. There are also cleaver devices available to place over the end of a plug to apply a lock. There are even little plastic devices that fit in circuit breaker panels to meet the same criteria (I don't like these).

For your case, if you accept the fact that shutting down the disconnect will disable both machines - I don't think the code prevents you from doing this.
In the event that both machines ever run at the same time, you want to be sure that the current rating of the disconnect and wiring are up to the task.

From your posting it is not clear if both machines are in the same location. If one is in the basement and one in the garage, then you may have to consider if it is a concern that unauthorized person might start one of the machines when you are at the other. I have my disconnects mounted above the reach of smaller grand kids, and leave the disconnects off when I am not around just for this reason. (When they get older or taller, I may have to resort to locking the disconnects).

Terry S.

 

[DMS]

Terry brings up some good things to consider. Considering the cost of a disconnect, I would be likely to just install another. I don't recall anything in the code to prevent this (though I am not a licensed electrician). I know we have some pros on here, who will hopefully chime in. If you do go this route, make sure that both runs are sized for the breaker feeding that disconnect.

Another option is to call your local inspector and ask them. the guys in my area are really helpful, and if they see a problem with your plan, they will direct you to a better (more compliant) solution. This is probably the best solution, as building codes differ from region to region.

 

[ranch23]

Lock Out Tag Out. Cheap and simple to use. Buy a lock, use it and keep the keys in your pocket until you are done. Please get in the habit.

 

[NoShopSkills]

Good ideas.

Yes the machines are both on the same floor, in the same building, same location. A dedicated, child free shop. A two and a half plus car garage. The stairs lead up to the second level, which is just unimproved material storage. The previous home owner put the stairs in the garage for some silly reason. I finally gave up on the idea of tearing them out and having two entrances for the building, so I've come to terms with the loss of square footage needed to accommodate a full set of 5' wide stairs in a garage.

A 60 inch lathe easily fits under the stairs, with good newly added overhead lighting and the disconnect on the knee wall that supports the stairs. Wire, breaker and shut-off all are overkill, even if both machines are running simultaneously. I had the 8 ga. wire and breaker on hand and only purchased the Eaton lever disconnect for the installation.

With neither corners nor wall space left open, the mill is large enough to sit in the center of the shop rather than cram the walls tight. Obviously you wouldn't want the power feed running on the floor, so it's going to have to come down from above. Therefore, after considering some of your input, maybe one disconnect serving both machines, actually meets the intent of the codes better than a second one bolted to the mill itself somehow.

The present set up is both in-sight and lockable even with the addition of the mill. As an aviator, having watched aircraft techs my whole life work on dangerous systems, tags and locks are ingrained in my habit pattern.

Wow. I didn't realize how indebted I would become to the participants here for their guidance.
Thanks again.

 

[Ray C]

Maybe I'm all wrong about this but, the "Code" rules you're talking about (in the context of this discussion) apply to commercial business that hire employees. In a home hobby shop, you won't get any surprise visits from an OSHA inspector. Obviously, it makes sense to keep yourself as safe as possible.

I have a single feed that supplies two, individually switched outlets located right next to each of two machines. I don't have a physical lock-out but, the switch can be flipped to de-energize either machine. I use this to power down the equipment at night and when I'm doing some sort of significant maintenance on the machine.

In this case, if you are the only one using your shop, I would do what makes sense and stick with procedures to keep yourself safe.

Ray

 

[NoShopSkills]

... the "Code" rules you're talking about (in the context of this discussion) apply to commercial business that hire employees. In a home hobby shop, you won't get any surprise visits from an OSHA inspector. Obviously, it makes sense to keep yourself as safe as possible. ... In this case, if you are the only one using your shop, I would do what makes sense and stick with procedures to keep yourself safe.

Ray

I think the same way. That's why I used the words, "meets the intent of the codes."

However, consider a scenario where kids had to sell the place in an estate liquidation. They would get all kinds of grief from prospective buyers and home inspectors if the machines were violating any local codes in their method of connection. The wife and kids might not realize how simple it would be to just remove the power drops from the panel and eliminate the "problem"... Another argument for actually doing it by BOCA or OSHA codes.

 

[Bill C.]

Lock Out Tag Out. Cheap and simple to use. Buy a lock, use it and keep the keys in your pocket until you are done. Please get in the habit.

That is what we used at GE. They gave us tags that we clipped in the lockout holes on the disconnect power box. Only a committee of company and union could legally remove it. A pad lock is still the best, keeps non-authorized personnel from turning on the shop equipment. Non-authorized personnel would be vistors and children.

 

[rdhem2]

There is no problem by national code supplying two machines with one circuit. As long as the circuit is adequate for the largest load served.

The correct wording for the location of disconnects is "within 50' and sight of" to be adequate.

Also I can only speak for the State of Washington where the Deputy Chief Electrical Inspector for Washington State once told me. "There is no such thing as common sense, there is only the code and our interpretation of the code". I hope the other forty nine are a little more flexible.

 

[Cheeseking]

Noshop sounds like you will be just fine with your setup. Nothing wrong going overkill on safety. As long as you have over current protection for the conductors and over load protection on the motors. A plug qualifies as a disconnect.

This is my setup Incoming 240V 60A 1P. Fused disconnect to motor starter w/ overloads to power 7.5HP RPC to 240 30A 3P fused disconnect feeding twist-lok outlets for mill, lathe and grinders.