Five things you need to know about CE Marked Wire and Cable

Wire is simple right? Maybe not! Here are the top five things to know when select­ing wire and cable products for use in designs that will be CE Marked:

  1. Wire and cable products sold in the EU must be CE Marked under the Low Voltage Directive, and MAY bear BOTH the CE Mark and the HAR mark. The HAR mark may only be applied by man­u­fac­tur­ers that have met the require­ments for the use of the HAR mark. More inform­a­tion on the HAR mark. 

    Picture of the HAR Mark.
    The HAR Mark
  2. The HD 21.X and HD 22.X Harmonization Documents pre­vi­ously used for determ­in­ing com­pli­ance and apply­ing the CE Mark are being replaced by the EN 50525.X fam­ily of stand­ards start­ing on 2014-​01-​17. See the list.
  3. Wire and Cable products with Declarations of Conformity that refer to older ver­sions of the Low Voltage Directive, or that refer to HD doc­u­ments that have been super­seded are NO LONGER COMPLIANT.
  4. Wire and Cable products used in “large-​scale” machine tools and fixed install­a­tions do not need to meet WEEE require­ments.
  5. Designers are not required to use CE Marked wire and cable products in CE Marked Products.

Need to know more? Check out this art­icle!

Five things most machine builders do incorrectly

Five things that most machine build­ers fail to do. With a Sixth Bonus fail­ure!

The Top Five errors I see machine build­ers make on a depress­ingly reg­u­lar basis:

1) Poor or Absent Risk Assessment

Risk assess­ments are fun­da­ment­al to safe machine design and liab­il­ity lim­it­a­tion, and are required by law in the EU. They are a included in all of the mod­ern North American machinery safety stand­ards as well.

Machine build­ers fre­quently have trouble with the risk assess­ment pro­cess, usu­ally because they fail to under­stand the pro­cess or because they fail to devote enough resources to get­ting it done.

If risk assess­ment is built into your design pro­cess, it becomes the norm for how you do busi­ness. Time and resources will auto­mat­ic­ally be devoted to the pro­cess, and since it’s part of how you do things it will become rel­at­ively pain­less. Where people go wrong is in mak­ing it a ‘big deal’ one-​time event. Also get­ting it done early in the design pro­cess and iter­ated as the design pro­gresses means that you have time to react to the find­ings, and you can com­plete any neces­sary changes at more cost-​effective points in the design and build pro­cess. The worst time to do risk assess­ment is at the point where the machine is on the shop floor ready to start pro­duc­tion. Costs for modi­fic­a­tion are then expo­nen­tially high­er than dur­ing design and con­struc­tion.

Poorly done, risk assess­ments become a liab­il­ity defense lawyer’s worst night­mare and a plaintiff’s lawyer’s dream. Shortchanging the risk assess­ment pro­cess ensures that you will lose, either now or later.

Fight this prob­lem by: learn­ing how to con­duct a risk assess­ment, using qual­ity risk assess­ment soft­ware tools, and build­ing risk assess­ment into your stand­ard design process/​practice in your organ­iz­a­tion.

2) Failure to be Aware of Regulations & Use Design Standards

This one is a mys­tery to me.

Every mar­ket has product safety legis­la­tion, sup­por­ted by reg­u­la­tions. Granted, the scope and qual­ity of these reg­u­la­tions var­ies widely, but if you want to sell a product in a mar­ket, it doesn’t take a lot of effort to find out what reg­u­la­tions may apply.

Design stand­ards have been in exist­ence for a long time. Most pur­chase orders, at least for cus­tom machinery, con­tain lists of stand­ards that the equip­ment is required to meet at Factory Acceptance Testing (FAT).

Why machine build­ers fail to grasp that using these stand­ards can actu­ally give them a com­pet­it­ive edge, as well as help­ing them to meet reg­u­lat­ory require­ments, I don’t know. If you do, please either com­ment on this story or send me an email. I’d love to hear your thoughts on this!

Fight this prob­lem by: Doing some research. Understand the mar­ket envir­on­ment in which you sell your products. If you aren’t sure how to do this, use a con­sult­ant to assist you. Buy the stand­ards, espe­cially if your cli­ent calls them out in their spe­cific­a­tions. Read and apply them to your designs.

One great resource for inform­a­tion on reg­u­lat­ory envir­on­ments and stand­ards applic­a­tions is the IEEE Product Safety Engineering Society and the EMC-​PSTC Listserv that they main­tain.

3) Fixed Guard Design

Fixed guard­ing design is driv­en by at least two factors, a) pre­vent­ing people from access­ing haz­ards, and b) allow­ing raw mater­i­als and products into and out of the machinery.

Designers fre­quently go wrong by select­ing a fixed guard where a mov­able guard is neces­sary to per­mit fre­quent access (say more than once per shift). This is some­times done in an effort to avoid hav­ing to add inter­locks to the con­trol sys­tems. Frequently the guard will be removed and replaced a couple of times, and then the screws will be left off, and even­tu­ally the guard itself will be left off, leav­ing the user with an unguarded haz­ard.

The oth­er com­mon fault with fixed guards relates to the second factor I men­tioned – get­ting raw mater­i­als and products in an out of the machine. There are lim­its on the size of open­ings that can be left in guards, depend­ent on the dis­tance from the open­ing to the haz­ards behind the guard and the size of the open­ing itself. Often the only factor con­sidered is the size of the item that needs to enter or exit the machinery.

Both of these faults often occur because the guard­ing is not designed, but is allowed to hap­pen dur­ing machine build. The size and shape of the guards is then often driv­en by con­veni­ence in fab­ric­a­tion rather than by thought­ful design and applic­a­tion of the min­im­um code require­ments.

Fight this prob­lem by: Designing the guards on your product rather than allow­ing them to hap­pen, based on the out­come of the risk assess­ment and the lim­its defined in the stand­ards. Tables for guard open­ings and safety dis­tances are avail­able in North American, EU and International stand­ards.

4) Movable Guard Interlocking

Movable guards them­selves are usu­ally reas­on­ably well done. Note that I am not talk­ing about self adjust­ing guards like those found on a table saw for instance. I am talk­ing about guard doors, gates, and cov­ers.

The prob­lem usu­ally comes with the design of the inter­lock that is required to go with the mov­able guard. The first part of the prob­lem goes back to my #1 mis­take: Risk Assessment. No risk assess­ment means that you can­not reas­on­ably hope to get the reli­ab­il­ity require­ments right for the inter­lock­ing sys­tem. Next, there are small but sig­ni­fic­ant dif­fer­ences in how the Canadian, US, EU and International stand­ards handle con­trol reli­ab­il­ity, and the biggest dif­fer­ences occur in the high­er reli­ab­il­ity clas­si­fic­a­tions.

In the USA, the stand­ards speak of con­trol reli­able cir­cuits (see ANSI RIA R15.06 – 1999, 4.5.5). This require­ment is writ­ten in such a way that a single inter­lock­ing device, installed with dual chan­nel elec­tric­al cir­cuits and suit­ably selec­ted com­pon­ents will meet the require­ments. No single ELECTRICAL com­pon­ent fail­ure will lead to the loss of the safety func­tion, but a single mech­an­ic­al fault could.

In Canada, the machinery and robot­ics stand­ards speak of con­trol reli­able sys­tems (see CSA Z432, 8.2.5), not cir­cuits as in the US stand­ards. This require­ment is writ­ten in such a way that TWO elec­tromech­an­ic­al inter­lock­ing devices are required, one in each elec­tric­al chan­nel of the inter­lock­ing sys­tem. This per­mits the sys­tem to detect mech­an­ic­al fail­ures such as broken or miss­ing keys, and if dif­fer­ent types of inter­lock­ing devices are chosen, may also per­mit detec­tion of efforts to bypass the inter­lock. Most single mech­an­ic­al faults and elec­tric­al faults will be detec­ted.

In the EU and Internationally, con­trol reli­ab­il­ity is much more highly developed. Here, the applic­a­tion of ISO 13849, IEC 62061 or IEC 61508 have taken con­trol reli­ab­il­ity to high­er levels than any­thing seen to date in North America. Under these stand­ards, the required Performance Level (PLr) or Safety Integrity Level (SIL) must be known. This is based on the out­come of, you guessed it, the Risk Assessment. No risk assess­ment, or a poor risk assess­ment, dooms the design­er to likely fail­ure. Significant skill is required to handle the ana­lys­is and design of safety related parts of con­trol sys­tems under these stand­ards.

Fight this prob­lem by: Getting the train­ing you need to prop­erly apply these stand­ards and then using them in your designs.

5) Safety Distances

Safety dis­tances crop up any­where you don’t have a phys­ic­al bar­ri­er keep­ing the user away from the haz­ard. Whether its an open­ing in a fixed guard, a mov­able guard like a guard door or gate, or a presence-​sensing safe­guard­ing device like a light cur­tain, safety dis­tances have to be con­sidered in the machine design. The easi­er it is for the user to come in con­tact with the haz­ard, the more safety dis­tance mat­ters.

Stopping per­form­ance of the machinery must be tested to val­id­ate the safety dis­tances used. Failure to get the safety dis­tance right means that your guards will give your users a false sense of secur­ity, and will expose them to injury. This will also expose your com­pany to sig­ni­fic­ant liab­il­ity when someone gets hurt, because they will. Its only a mat­ter of time.

Fight this prob­lem by: Testing safe­guard­ing devices.

6) Validation

OK, so this list should really be SIX things. Just con­sider this to be a bonus for read­ing this far!

Designs, and par­tic­u­larly safety crit­ic­al designs, must be tested. Let me say it again:

Safety Critical Designs MUST Be Tested.

Whatever the­ory you are work­ing under, wheth­er it’s North American, European, International or some­thing else, you can­not afford miss­ing the val­id­a­tion step. Without val­id­a­tion you have no evid­ence that your sys­tem worked at all, let alone if it worked cor­rectly.

Fight this prob­lem by: TESTING YOUR DESIGNS.

A wise man once said: “If you think safety is expens­ive, try hav­ing an acci­dent.” The gen­tle­man was involved in invest­ig­at­ing the crash of a Sikorsky S-​92 heli­copter off the coast of Newfoundland. 17 people died as a res­ult of the fail­ure of two titani­um studs that held an oil fil­ter onto the main gear­box, and the fact that the heli­copter failed the ‘1/​2-​hour gear­box run-​dry test’ that is required for all new heli­copter designs. This was a clear case of fail­ure in the risk assess­ment pro­cess com­plic­ated by fail­ure in the test pro­cess.