230v Estop

I got switched to a different project... but I believe we are going with 120V on one machine and 24V on the other. The machine is far over budget already, and we are trying to save money every way we can.

And to answer some of your questions about not being an electrician and doing electrical work, I believe it is because im building a panel from scratch that im allowed to do it (but to be honest, I really dont know the exact legality behind it), and that CSA approves the machine before it goes out the door.

thanks for your replies

In Canada with panel building etc, it's legal to have a monkey wire it, as long as someone takes responsibility for the finished product before it leaves the shop, whereas you would need to be an electrician to wire up a hot tub at someone's house (unless it's your own), or field wire a motor etc, so nobody gets fried. The rules are different in other countries, as are the fatality statistics.

When you say somebody has to take responsability for the panel, is that somebody supose to be an electrician?

When you say somebody has to take responsability for the panel, is that somebody supose to be an electrician?


No, They can be in a management position, so long as they have the ability to pass the buck and blame someone else.

Roger

Just so you know - it is not ILLEGAL to do your own wiring - You just can't sell or use it until a licenced electrician (or agency) inspect it. If you use CSA parts in an item - does not mean the completed item is CSA approved - IT IS NOT! If you WORK in a CSA approved PLANT then that company (in general) has to maintain CSA ratings (though processes/training/reviews as well as testing ect).

You can get local inpections/approvals done by your local Electricity supplier (not CSA but per unit inspected/approved for local/regional use).

There is other rating that an item may have that is approved for use in Canada such as "Intella" - an international rating? - slighly differnt but overall much like CSA.

This was a big thing when a few years ago every "geek" was "assembling" computers in there basements and selling them. If they are not an approved shop (yea right - they would not be in a basement) and don't get each unit inspected, then they are not approved - even if everyting they use and put in is CSA approved. All you have to do is cross a wire (ie IDE cable) and something may not work. Ground the wrong wire and you have another defnition of hitting the POWER button - shocking!

Just my 2 cents worth....

BTW - in some areas in Canada (don't know if it is all) a home owner may do his own minor wiring without requiring inspection (but you can't do your frends ect...). Limited to standard house currents - single phase only. I know this as I help built my parents-in-law's new home "they" did there own wiring... (okay - maybe I had something to do with that - but I can't say). All legal.

E-Stop

The correct way to address your problem would be to assess the risk of your machine and install a monitored safety relay to suit such as Pilz PNOZx3 which would take your power supply rail and create a monitored E stop and reset facility at a safe low voltage with monitored control contacts to control your contactors/ relays.
Reference http://www.bara.org.uk/encyclopedia/pilz/piltz.htm

Thats a good point, very workable solution. I have 18 machines using a Telemecanique safety monitoring relay that does just that.

BTW I had to replace one of those monitoring relays recently and the average cost is around $700 US for the major brands, Sick has one similar for around $150 US. I havent gotten the SICK unit yet but I am going to order one, my company likes the cheap options.

UL Listings

If I am not mistaken all electrical equipment installed in the US should have a valid UL label. You can build a control panel and wire the assocated machine and have a UL inspector come on site and inspect it and attach a UL label if it passes. Next you need an inspection permit to have the final connections that are made on site by a local approved inspection agency. In Ohio and Ky. we have to be licensed to even get a permit for commercial or industrial installations, which often requires drawings and plan reviews of the same. The NEC also says all electrical work is to be inspected. I have had a UL inspector on site before to have this done. All of the above lessens the liabilty for the panel/machine builder and installer. I see to much of this done in-house with none qualified persons on a daily basis with NO inspections to save a buck. I would not want to be responsibly for that liability if someone got injured. In Ky. unless you have a license you are not allowed to make ANY new installations. [EXAMPLES] You are only allowed to make repairs to an existing outlet but not extend that outlet. You are allowed to replace an existing motor starter but not allowed to add a new motor and starter on a machine tool. 480/240 volt controls may be OK for a local self contained combination starter, but I suggest you NEVER wire remotes, PBs, Pilots, Valves, etc., with those voltages, especially on a DELTA system. 120 volt control is OK, because it is grounded and bonded, but when it comes to wet locations go to 24 volts AC or DC for safety reasons. Also use Nema 4 or 4X boxes for a longer lasting and safer job. I have held a license in both Ohio and Ky. for the past 25 years, been in the trade for 40 years and I still have to attend courses each year to keep up my credit hours to retain the licenses. And also have recently joined the International Association of Electrical Inspectors which is another good organization.

Leon

Add this to the last reply.

Steve,

One of the first things I learned in this trade was that the electrical codes are written as a minimium set of standards and that you can do BETTER. I just hate it when someone says we are under budget and need to save money and sacrifice quality and safety. The person that taught me that was an electrical inspector about 32 years ago in a small code seminar he presented. He turned on a light for me that day with that comment. He is still with us in the same agency and now is the chief electrical inspector in our area and a good friend of mine now. He is also the president of my local chapter of the I.A.E.C. and was just presented the honor of being voted the electric man of the year in Ohio. To me that is a great honor, but he deserves it.

Leon

Leon, you said: "If I am not mistaken all electrical equipment installed in the US should have a valid UL label."

Not true. In fact, the NEC is applied in most (if not all) US jurisdictions, but only because most state and local building codes invoke it by reference. This is also true of UL standards - UL is not a legislative or governmental agency.

Furthermore, you have to make a distinction between the UL label on individual components and consumer electrical appliances, which again is almost universally invoked by reference in local fire and building codes, and UL-508. UL-508 is a standard specifically designed for custom industrial electrical control systems. In my experience, it is not at this time mandatory in most US jurisdictions but is, unfortunately, spreading.

Tom Jenkins

Tom,

I liked your reply. Yes I was refering to custom systems which are mostly done in an in house shop. UL listing has become a BIG issue here in Cincy. Just did a Church job with low voltage lighting (small fixtures) 12 volts with no UL listings attached to the fixtures, which is another issue. Our chief inspector is big on getting this issue resolved. The manufacturer said the listing ( UL label) was on the box and in the literature provided. Our local agency says that is not good enough. RE: (listed systems) such as outdoor low voltage lighting systems. The big problem here is that the fixtures are too small to affix a label to. Attachments from the manufacturer had to be attached to my permit and on file to get approval. Our agency is BIG on this for some reason. In our last I.A.E.I. meeting we had a rep. from Sea Gull lighting attend and his input from all of us was why not mark everything with a UL label and make it easier on us contractors and inspectors. They say you can mount a transformer in a kitchen cabinet, but need 12" clearence on all sides and the front. I am sure my wife would read that and adhere to the instructions.

Leon

NFPA 79 "Electrical Standard for Industrial Machinery" recommends under section 9.2.1 "Alternating-current (ac) control voltage shall be 120 volts or less, single phase."

I worked for an automation company several (...more than several?) years ago. I designed the control cabinets, wrote the programs, and followed the machine into the field for installation. At the installation site, I was always subject to the local laws. Sometimes that meant I had to have a local electrician do any work external to the system... the internals of the system, however, were mine.

I used the NEC as a guide for certain minimum and maximum constraints. As mentioned, in a lot of cases the NEC represents the LEAST that must be done... you are certainly allowed to do better!

Of course, the NEC doesn't tell you how - the NEC is NOT a "How-To-..." book. The NEC is only a guide.

Panels built by OEM's are not subject to the NEC (more on this later). Nor were they required, as a System, to be UL-Approved (more on this later). My panels were not assembled by "Electricians". They were assembled by "Technicians"... this is about as broad and general a term as there is... anyone can be hired as a "Technician" for this purpose.

In many places, throughout the NEC, you can find "Notes" and "Exceptions" included with many of the various Articles and Tables. While a particular Article or Table specifies "Such-n-such", you sometimes find a "Note" or "Exception" that indicates that the particular practice or limit can be superceded, if properly "Engineered".

Which is to say... when it comes to "designing systems", the NEC bows to the Engineer. That phrase, "designing systems", is rather nebulous... it's a grey-area. The reason is, the NEC can not, and will not, attempt to make specifications for every possible "system" that might come down the line... it can't!

Since the NEC has been developed, and is maintained, by Engineers to begin with, the NEC Board has very little choice but to recognize that other Engineers are equally qualified to make "design-decisions"!

This is what gives the OEM's their latitude.

I think the NEC assumes that the "Engineering" will be done by a P.E. (a Registered, Profesional Engineer).

I've never found where the status of the Engineer is specified. If not specified, then I think that leaves the door open for any engineer... registered or not, degreed or not.

I think the phrase "Registered, Professional Engineer" is all-inclusive... that is, it includes Electrical Engineers, Mechanical Engineers, Chemical Engineers,... et al.

We (here at PLCS.net) used to have a P.E. make an appearance now and then... I wonder if he's still out there lurking. Maybe he can put me straight on this.

At any rate, we operated under the authority provided by that "Note" or "Exception". While following the UL Standards as closely as possible, we were never required to acquire a "System" UL sticker. For particular situations, we did, occasionally, use components (especially computer-type components) that did not have UL stickers.

An important fact to note...
The NEC is NOT the Law of the Land! The "N" in NEC stands for National. However, Electrical Laws (Rules and Regulations) are "LOCAL" affairs... that is, each State determines its' own Electrical Laws. Each State "chooses" whether or not to abide by the NEC. In all cases, the "Local Jurisdiction" has Authority to over-ride the NEC. ("Local Jurisdiction", in some cases, is at the County level.)

When a new issue of the NEC comes out, each State that has chosen to follow the NEC goes through the process of "Ratifying" the NEC into Local Law. At that point, the "Local Jurisdiction" can, and often does, encourage the State to ratify the NEC with Exceptions.

This means, if the State chooses to use the NEC at all, it can modify the NEC to its' own liking! The modification to the code can be more or less strict, as the State chooses. Everytime a new NEC comes out, Oregon also issues an "Exceptions" booklet. In fact, sometimes there is so much in-fighting that the new NEC is not ratified until a year or so after the initial release! It really screws up the "Current Continuing Education Requirements".

I won't argue the merits of "Full Acceptance" vs. "Acceptance with Exceptions"... the rationale is that the Local Jurisdiction knows what they are doing. And even if they don't, they are still the Local Jurisdiction!

Lately, some States have started to require that any electrical systems (or individual electrical devices) being sold into the State, from outside the State (either from another State or Country), must be UL Approved - as a System! (Oregon is one of those States. Some States have required this for a longer period of time.)

I don't really know what the law is for Intra-State (within the State) sales.

At any rate, it is becoming more and more sensible for OEM's to ensure that their systems are either UL-Approved up-front, or can withstand a UL-Inspection on-site.

Again, for delivery to any particular State, whether or not this is required depends on the "Authority having Local Jurisdiction". Even though it drives up the cost, it just makes more sense to eliminate the issue before it is an issue.

As far as having Licensed Electricians doing the assembly, a particular company might have that requirement, but I don't know of any State that has such a requirement. (That does not mean there isn't one!)

I wonder if all States are now operating under the NEC. It wasn't too long ago that several were not... nor did they have any electrical license requirements. One of my first jobs, long before I ever considered the idea of Electrical Engineering, was as an Electrician in Illinois ... no license required. (I think Tesla just got his new-fangled AC-System on-line.)


shahn4 said...
NFPA 79 "Electrical Standard for Industrial Machinery" recommends under section 9.2.1 "Alternating-current (ac) control voltage shall be 120 volts or less, single phase."

"recommends" and "shall be" are contradictory.

"79"??

Terry Woods said:

"79"??

Click to expand...

Terry, are you asking "What is NFPA 79?"

Don't tell me that YOU don't have a copy of NFPA 79 ?!?!?!...

Or, worse yet, have not heard of it?...

beerchug

-Eric

Oh, and thanks shahn4 for finding that definition... I KNEW it was in there somewhere!...

Duuuuhhhh.... you mean that ain't the "1979" issue?