Emergency power off, a question for sidewinder and others?

[Phoenix]

I'm looking for a link which gives a brief outline of the requirements of emergency stop systems.

Basically I have come across a commerical kitchen and there are stop buttons which are of the none mushroom head type, also none latching which are postioned in a plywood box with a side out clear cover (presumably to prevent nuisence pressing), one for gas, one for electricity, they are not labeled as which one is what. The gas one is wired back to the boiler panel in the plant room and causes a latching condition on the panel which drops out the gas valve for the kitchen, the power one switches a live from an MCB in the local DB onto the shunt trip unit on the MCCBS supplying the kitchen submains in the main panel.

I'm concerned about a few issues, namely that its possible to reset the fault condition without having to attend and unlatch stop buttons, that they are unlabeled and not easy to strike in an emergency, and that the system if not failsafe, if the MCB for the stop system were to be switched off, then there is no power to operate the shunt trip.

Also on the same site got a number of stop systems which just use a contactor to switch off power to an area, am I right in thinking that these need to be special possitivly driven types, rather than just standard ones which rely on the springs returning the contacts to the open position

I am aware that its a a complicated issue and some of its on risk assessment as to what class of system as requiresd. This is a PIR and while emergency stop systems are excluded (as are fire alarms and emergency lighting). We generally if seeing something with these systems that seems non compliant with teh relevant standard, flag it up and recommend a detailed assessment into the relevant system.

So just wanted a quick overview just to make sure that I wasn't pulling up 'non issues' or anything like that

Many thanks

A.

 

[Andy™]

dont know much about emergency stop systems, but im sure they are supposed to be wired where the stop button breaks the circuit, so if the control circuit failed, then the power would go off

 

[Manator]

The HSE do have some basic information on their site

HSE - Electricity - Electrical standards and approved codes of practice

I have not read any of it but it may be a useful reference for you to start.

From the lists you can see the relevant British Standards and research from there.

 

[Sidewinder]

Phoenix,

Don't know the requirements for gas, however as far as I know there are no requirements for a shut down system like this in a commercial kitchen.

However, if it is fitted then it must comply with statutory regs.

I got confused reading your post, more me than you I think.

Have a look on the HSE website for L22, just search L22 on the home page the doc you want is the first one that comes up an a search for me.

Have a look at the control system requirements there in and see if yours complies, this is statute law too.

Basically the system must NOT reset on releasing the stop, the stop must stay in.

The rest of it gets more complex.

We can sort you out nae bother.

Stick around, keep asking and look at that doc and then see where the system stands.

REMEMBER though you can't fail it on a PIR, and you need to be careful offering consultancy and other such "advice" unless you have the quals and PI insurance to back you up.

This is one of the reasons my insurance is through the roof compared to the rest of you!!!

BTW

I have an issue with my internet at home being very intermittent, been off all day!

External fault, so have to wait for Virgin to sort!

Joint issue affecting a load of houses, though they won't rush so I may be on and off for a few weeks now apparently!

If I don't respond then it's probably due to this!

 

[Andy™]

I have an issue with my internet at home being very intermittent, been off all day!

External fault, so have to wait for Virgin to sort!

Joint issue affecting a load of houses, though they won't rush so I may be on and off for a few weeks now apparently!

If I don't respond then it's probably due to this!

demand any down time is deducted from your bill. and mention it to your neighbours too. done this a while back when net was off for 2 1/2 days (someone in a digger to blame for that one)

 

[Apache]

External fault, so have to wait for Virgin to sort!

You'll struggle to find one of them in your part of the world

 

[nsbs]

There is (was) a requirement to install emergency shut down to the gas valve in an commercial kitchen (depending on the size) however, this is for new kitchens and wont be applied retrospectively. (think the COP were introduced in 1998

 

[nsbs]

Just looked through my H&S stuff and noted that the requirement is in Gas Safety (Installation and Use) Regulations 1998, which states there is a requirement to install gas suppression and automatic shut off, of gas appliances. These can either be mechanical or electrical devices. As far as I can remember, its basically a stop button, controlling a relay, which has an interface to solenoid on gas valve.

But I think this is a bit outside the scope of 7671, and you will need to be careful of the advice you offer.

 

[ProDave]

There's a whole lot to designing emergency stop systems (I used to do a lot of that for industrial machinery) but it all begins with a risk assessment, from which you determine the category of the stop circuit required and design it accordingly.

But even the lowest category requires it to be fail safe, so at very least a normally closed contact on the EM stop button, holding a contactor coil energised, and in the event of the button being pressed, the contactor will open, and will NOT re energise without pressing some sort of reset button. Higher categories require redundancy, dual pole EM stop buttons, proper safety relays, and even two contactors in series, all to ensure a single failure won't prevent the stop system from stopping (but that single failure would prevent it from re starting)

What's there at present is a joke and should be ripped out and replaced with a correctly designed system.

 

[septiclecky]

You'll struggle to find one of them in your part of the world

You will it's the sheep that need to be worried.

 

[Evans Electric]

Commercial kitchens will have a stop button system and often heat detectors and even soldered links on a pulley wire system that usually shuts the main gas valve off. As far as I remember they have to be reset manually.

The buttons that isolate certain areas may be just for safety reasons , as when the staff go home , the sockets are switched off from one position .

You say the gas one latches in the off position so that sounds correct to me .

However , as mere electricians its not in our remit to be designing and advising on such matters . Unless you are a qualified electrical design engineer of course.

I agree that they should be labled for H&S reasons but again , that not within your remit TBH.

 

[Phoenix]

Forgot I posted this O)

Thanks for all your respsonses, I'll make sure its carfully phrased as to not offer advice out of scope and to recommend suitabe assessment