Commercial Kitchen Extraction

[MeFil]

I'm presently working on a restaurant renovation and there are two sets of contractors working on site. One responsible for the front of house. The others fitting the commercial kichen and extraction. I'm not particularly happy with the standard electrical work on the kitchen side of things. Specifically on how the ventilation system has been installed. So I thought I'd ask the following questions to see if I'm being a nag unnecessarily.

Here's the set up as is...

Four fans in the roof. All single phase. One air intake. Three extract

The largest fan is the kichen range extractor. Rated at 11.5 amps

The other fans are all smaller in size and rated 4.5 amps.

The kitchen extractor is wired from the distribution board via a 20a mcb directly to the gas interlock. And then onto the fan via a speed control unit.

The other three fans are wired via one 20 A mcb to three switched fcu's using 2.5 t+e. Then onwards to the fans. One goes via another gas interlock system.

Hope that info makes sense.

So my concerns are around safe isolation and maintenance. In my world I would have provided each fan with its own mcb. And connected each fan to an isolation switch (marked with a 1 and 0) and then on to the control switches and gas interlocks etc...

Section 537.3 seems to be the relevant section. Specifically as there are rotating parts and the isolation points as installed are remote from the fan units.

So the question. Anyone happy with as installed? Are there any other regs that are pertinent ? Or should I just mind my own business as its not my job.

 

[Manator]

I personally would prefer the way you suggest. If I was installing such I would provide lock off facilities on the isolators rather than have fused spurs.

Taking the three fans from one mcb should not be a problem.

If I was doing any maintenance on this install I would have to use a lock off on the distribution board, not a very good way of doing anything, I would much rather see my lock on an isolator! next to where I am working.

 

[MeFil]

I agree. I can't see anything wrong electrically with it. It just doesn't seem right to me somehow.

 

[Andy™]

you can lock most fused spurs

 

[MeFil]

The largest fan is rated at 4.5kw. The other fans are 1.5 kw . I don't believe that there is any thermal prote tion on them.

 

[MeFil]

552.1.2  :innocent

I knew that there would be more to this.

I only questioned how the fans were being installed after I viewed some of their other work. (I kept noticing cables with the live conductors bent back and wrapped in insulation tape)

 

[kme]

Are there rotary iso`s on the roof, next to ( or on) the ductwork? This is a common location for `em on commercial extraction.

And taking the fan supply directly through the gas interlock???? How the hell is THAT wired??

The interlock needs to shut off if the fan isn`t sucking. If an upstream event occurs, that doesn`t take out the OCPD, what shuts off the gas?

Something doesn`t sound right here................

 

[MeFil]

4 fans inline with the duct work located in the loft space above the shop. One supply, three extract.

Supply is fresh air to the kitchen. One extract is from the toilet. The other two are from the range and a cooker.

The gas interlock detects current to the fan. No pressure switches.

As I've said, the set up thing seems wrong..(too domestic) to me and I have raised my concern with the client. Been looking for relevant regs to back me up.

All I can say about the people that have fitted it is that they do a lot of work in Chinatown.

 

[MeFil]

Have the Environmental Health approved all the airflow calculations (for air changes) for everything ?

That I don't know....but if I was taking a guess....

 

[Evans Electric]

To be honest I would normally keep my nose out of other's work unless I could see an obvious danger to life .

I'd be interested in what the gas interlock wiring is though.     Can you not light the gas without the fans or what . ?  Might explain why theres no local isolator by the fans .

 

[Evans Electric]

That makes sense.

 

[Sidewinder]

I thought that the gas interlocks on a commercial kitchen "HAD" to be interlocked to the extraction level on the output side of the fan?

 

[MeFil]

http://www.medem.co.uk/products/sip-1-service-isolation-panel-148 is what has been fitted. First time I've looked at the spec. It seems capable of switching 5 amps... and is running a fan drawing 11.5a..... ! unless I'm reading it wrong.

To be honest I would normally keep my nose out of other's work unless I could see an obvious danger to life .

I only became interested when, having spent a day replacing a tp+n board, I discovered all the fan supply cables were no longer in the board. Then my fcu for the handrier vanished. Then I found the live cables hidden in a void with live wire taped back on the insulation to make it safe.... but my Chinese wasn't up to scratch to make my feelings felt..

 

[Andy™]

I thought that the gas interlocks on a commercial kitchen "HAD" to be interlocked to the extraction level on the output side of the fan?

everyone ive seen is on the input side where the pressure is lower than normal

 

[Sidewinder]

Yes Andy, I know what you mean.

I don't think I explained myself at all well!!!

The "checking" device, should be checking airflow,in the duct, at whichever location is best really.

It should not be monitoring say for example that a contactor is "in" as proof that the fan is running efficiently.

Not a very well worded statement I have to admit.

I was thinking about the "output" side being airflow, and the "input" side being the electrickery.

No good monitoring the electrickery stuff, input, you need to monitor the airflow, output.

Does it make sense now?

 

[Medem]

Hi Guys my name is Stuart and full disclosure work for Medem, we manufacture the panel MeFil has mentioned with regards to the interlock. i just wanted to make contact to try and clear up any queries regarding the interlocking of fans in a commercial kitchen.

I'll try not to be to wordy and apologies if anyone thinks i am high-jacking the thread, we are specialists on the current legislation and standards for interlocking in commercial kitchens.

• All mechanical ventilation in a commercial kitchen MUST be interlocked - this is for both supply and extract.
• Interlocking can only be by air flow or current monitoring of a running fan - not power monitoring

Correctly installed and set up current monitoring is allowed by the HSE following the publication of Catering Sheet 23 revision 1, it was deemed to be a more reliable long term method of interlocking as the likely hood of the blades coming off is considerably less when compared to the failure of DP switches due to grease condensate build up etc. 

As a side note the panel mentioned is an isolation panel for a valve and should not be used to switch a fan, the 5amp limit is for switching a connected isolation valve. The fan would have to be operational before the SIP panel was switched on and it sounds like the panel could be being used outside of its design parameters.

Again apologies if you think i have high-jacked a thread and look forward to answering any question you might have.

 

[MeFil]

Hi Guys my name is Stuart and full disclosure work for Medem, we manufacture the panel MeFil has mentioned with regards to the interlock. i just wanted to make contact to try and clear up any queries regarding the interlocking of fans in a commercial kitchen.

I'll try not to be to wordy and apologies if anyone thinks i am high-jacking the thread, we are specialists on the current legislation and standards for interlocking in commercial kitchens.

• All mechanical ventilation in a commercial kitchen MUST be interlocked - this is for both supply and extract.
• Interlocking can only be by air flow or current monitoring of a running fan - not power monitoring

Correctly installed and set up current monitoring is allowed by the HSE following the publication of Catering Sheet 23 revision 1, it was deemed to be a more reliable long term method of interlocking as the likely hood of the blades coming off is considerably less when compared to the failure of DP switches due to grease condensate build up etc. 
As a side note the panel mentioned is an isolation panel for a valve and should not be used to switch a fan, the 5amp limit is for switching a connected isolation valve. The fan would have to be operational before the SIP panel was switched on and it sounds like the panel could be being used outside of its design parameters.

Again apologies if you think i have high-jacked a thread and look forward to answering any question you might have.

Thank you for that. .... I will check to ensure when I am next on site that I identified the panel correctly.

Thanks everyone for all the comments. Helped a lot.

 

[steptoe]

Hi Guys my name is Stuart and full disclosure work for Medem, we manufacture the panel MeFil has mentioned with regards to the interlock. i just wanted to make contact to try and clear up any queries regarding the interlocking of fans in a commercial kitchen.

I'll try not to be to wordy and apologies if anyone thinks i am high-jacking the thread, we are specialists on the current legislation and standards for interlocking in commercial kitchens.

• All mechanical ventilation in a commercial kitchen MUST be interlocked - this is for both supply and extract.
• Interlocking can only be by air flow or current monitoring of a running fan - not power monitoring

Correctly installed and set up current monitoring is allowed by the HSE following the publication of Catering Sheet 23 revision 1, it was deemed to be a more reliable long term method of interlocking as the likely hood of the blades coming off is considerably less when compared to the failure of DP switches due to grease condensate build up etc. 

As a side note the panel mentioned is an isolation panel for a valve and should not be used to switch a fan, the 5amp limit is for switching a connected isolation valve. The fan would have to be operational before the SIP panel was switched on and it sounds like the panel could be being used outside of its design parameters.

Again apologies if you think i have high-jacked a thread and look forward to answering any question you might have.

now that I like,

why cant everyone just be straight up and honest with an opening post,?

and good info too. 

 

[kme]

Excellent post, Stuart.

Thank you. I too, was unaware that current monitoring was acceptable - every system I`ve worked on / around used airflow / pressure differential switching.

The last one was a PITA. They`d installed fire suppression systems, and needed them interlocked to the gas supplies. 

BUT

The premises has two kitchens, one on the ground floor, and one below it ( which also equates to gnd floor at the rear of the building, due to the slope........)

Each kitchen has its own gas interlock, canopy, extraction, and fire suppression system - but our thinking was that, in the event of a fire event in the either kitchen, it would be preferable for the gas in BOTH kitchens to be interrupted.

There followed a bit of fannying about with contactors, to create the correct logical operation, whilst ensuring failsafe operation - without compromising the operation of either of the fan interlock systems.

 

[Sidewinder]

Yes a good post, but, personally I don't think I would be happy with current monitoring, as there can be more failure modes which reduce or cause the airflow to fail than that which could be detected by motor current monitoring.

Also, one must consider that whilst COSHH generally does not fully apply to kitchen LEV, and I admit I am not familiar with the gas regulations, I am very familiar with the requirements of PUWER98 & the current requirements for control systems design under the Machinery Directive & the Low Voltage Directive.

A gas control system I feel could come under either or both of the latter, and I would expect the former.

So, any equipment used or systems designed to control the gas would be to coin a perhaps more understandable phrase than those used in many standards a "safety related part of a control system", thus one must be involved with Performance Levels, Failure Modes, Mean Time Between Failure, etc, which makes bespoke systems a nightmare.

I am VERY surprised by HSE allowing only motor current monitoring as the fail safe!

I suspect that if this were to malfunction, then HSE would throw the suitability of this back onto the system designer & their design FMEA's and RA's.

Which I have no doubt would be proven to be inadequate...