Tag: lockout

Con­trol of haz­ardous ener­gy is one of the key ways that main­te­nance and ser­vice work­ers are pro­tect­ed while main­tain­ing indus­tri­al equip­ment. Not so long ago we only thought about ‘Lock­out’ or ‘Lockout/Tagout’ pro­ce­dures, but there is much more to pro­tect­ing these work­ers than ‘just’ lock­ing out ener­gy sources. Inevitably con­di­tions come up where safe­guards may need to be removed or tem­porar­i­ly bypassed in order to diag­nose prob­lems or to make crit­i­cal but infre­quent adjust­ments to the equip­ment, and this is where Haz­ardous Ener­gy Con­trol Pro­ce­dures, or HECP, come in.

One of the ques­tions I often get when help­ing clients with devel­op­ing HECPs for their equip­ment is, “Can we use the emer­gency stop cir­cuit for lock­out?” As usu­al, there is a short answer and a long answer to that sim­ple ques­tion!

The Short Answer

The short answer to this ques­tion is NO. Lock­out requires that sources of haz­ardous ener­gy be phys­i­cal­ly iso­lat­ed or blocked. Con­trol sys­tems may be able to meet parts, but not all of this require­ment. Read on if you’d like to know why.

The Long Answer

Lockout

Lock­out pro­ce­dures are now grouped with oth­er adjust­ment, diag­nos­tic and test pro­ce­dures into what are called Haz­ardous Ener­gy Con­trol Pro­ce­dures or HECP. In the USA, OSHA pub­lish­es a lock­out stan­dard in 29 CFR 1910.147, and ANSI pub­lish­es ANSI Z244.1.

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In Cana­da, we didn’t have a stan­dard for HECP until 2005 when CSA Z460 was pub­lished, although all the Provinces and Ter­ri­to­ries have some lan­guage in their leg­is­la­tion that at least alludes to the need for con­trol of haz­ardous ener­gy. In the Province of Ontario where I live, this require­ment shows up in Ontario Reg­u­la­tion 851, Sec­tions 42, 75 and 76.

In the EU, con­trol of haz­ardous ener­gy is dealt with in ISO 14118:2000, Safe­ty of machin­ery — Pre­ven­tion of unex­pect­ed start-up.

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If you have a look at the sec­tions of the Ontario reg­u­la­tions, they don’t tell you how to per­form lock­out, and they make lit­tle men­tion of what to do with live work for trou­bleshoot­ing pur­pos­es. The US OSHA reg­u­la­tions read more like a stan­dard, but because they are in leg­is­la­tion they are pre­scrip­tive. You MUST meet this min­i­mum require­ment, and you may exceed it.

Let’s look at how “lock­out” is defined in the stan­dards.

As you can see, the def­i­n­i­tions are fair­ly sim­i­lar, although slight­ly dif­fer­ent terms may be used. The ISO stan­dard actu­al­ly pro­vides the best guid­ance over­all in my opin­ion. Note that these excerpts are all tak­en from the def­i­n­i­tions sec­tions of the rel­e­vant doc­u­ments.

One of the big dif­fer­ences between the US and Cana­da is the idea of ‘tagout’ (pro­nounced TAG-out for those not famil­iar with the term). Tagout is iden­ti­cal to lock­out with the excep­tion of the device that is attached to the ener­gy iso­lat­ing device. Under cer­tain cir­cum­stances, the US per­mits the use of a tag with­out a lock to secure the ener­gy iso­la­tion device. This is not per­mit­ted in Cana­da under any cir­cum­stance, and the term ‘tagout’ is not offi­cial­ly rec­og­nized. In Cana­da, the term is often tak­en to mean the addi­tion of a tag to the lock­ing device,  a manda­to­ry part of the pro­ce­dure.

Use of Controls for Energy Isolation

This is where the ‘rub­ber meets the road’ — how is the source of haz­ardous ener­gy iso­lat­ed effec­tive­ly? To under­stand the require­ments, let’s look at the def­i­n­i­tion of an Ener­gy Iso­lat­ing Device.

As you can see from the above def­i­n­i­tions, all the juris­dic­tions require that devices used for ener­gy iso­la­tion are reli­able, man­u­al­ly oper­a­ble, mechan­i­cal devices. While elec­tri­cal con­trol sys­tems that meet high lev­els of design reli­a­bil­i­ty may meet the reli­a­bil­i­ty require­ments, they do not meet the require­ments for phys­i­cal, mechan­i­cal dis­con­nec­tion of the source of haz­ardous ener­gy. Oper­a­tor devices are specif­i­cal­ly exclud­ed from this use in Cana­da and the USA. Note that plug and sock­et com­bi­na­tions are per­mit­ted in all juris­dic­tions. Lock­out devices such as Brady 65675 Large Plug Lock­out Device, like the Brady Small Plug Lock­out Device shown here and sim­i­lar devices, can be used for this pur­pose. With some plugs, it is pos­si­ble to put a small lock through a hole in one of the blades or pins. In some juris­dic­tions, even the sim­ple act of putting the plug in your back pock­et while con­duct­ing the work is suf­fi­cient.

In addi­tion, the ener­gy iso­la­tion device is required to be able to be locked in the off, iso­lat­ed, or blocked posi­tion. There are emer­gency stop but­ton oper­a­tors that can be pur­chased with an inte­grat­ed lock cylin­der, and there are some con­trol oper­a­tor acces­sories avail­able that will allow con­trol push­but­tons and selec­tor switch­es to be locked in one posi­tion or anoth­er, but these do not meet the require­ments of the above stan­dards. They can be used in addi­tion to an ener­gy iso­la­tion device as part of the pro­ce­dure, but not on their own as the sole means of pre­vent­ing unex­pect­ed start-up.

Conclusions

Each machine or piece of equip­ment is required to have a HECP that is spe­cif­ic to that piece of equip­ment. ‘Glob­al’ HECP’s are sel­dom use­ful except as a tem­plate doc­u­ment. Devel­op­ment of HECPs takes some care­ful thought and a thor­ough under­stand­ing of the kinds of work that will need to be done to main­tain and ser­vice the machin­ery. Indi­vid­ual juris­dic­tions have some dif­fer­ences in the details of their reg­u­la­tions, but ulti­mate­ly the require­ments come down to the same thing: Pro­tect­ing work­ers.

Con­trol sys­tem devices such as stop but­tons and emer­gency stop devices are not accept­ed as ener­gy iso­lat­ing devices and can­not be used for this pur­pose, although they may be used as part of the HECP shut­down pro­ce­dure lead­ing up to the phys­i­cal iso­la­tion of the haz­ardous ener­gy sources.

Excel­lent stan­dards exist that cov­er devel­op­ment of these pro­ce­dures and should be ref­er­enced as spe­cif­ic HECP are devel­oped.

5% Dis­count on All Stan­dards with code: CC2011

References

Canada

Ontario Reg­u­la­tion 851, Sec­tions 42, 75 and 76.

CSA Z460-05 (R2010) — Con­trol of haz­ardous ener­gy — Lock­out and oth­er meth­ods

USA

29 CFR 1910.147 — The con­trol of haz­ardous ener­gy (lockout/tagout).

ANSI Z244.1 — 2003 (R2008) — Con­trol of Haz­ardous Ener­gy – Lockout/Tagout and Alter­na­tive Meth­ods

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International

ISO 14118 2000, Safe­ty of machin­ery — Pre­ven­tion of unex­pect­ed start-up

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