Discuss Hospital Emergency Power System in the Electrical Forum area at ElectriciansForums.net

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Cookie

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And one question- I can legally supply backup power for the whole site via one ATS?
 

snowhead

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but what do they mean by "risk grade"?
The level of Risk of an electrical supply failure causing harm to Patients and or the Business.

Example,
Loss of power to Car park lighing .

Risk Grade 4. Consequences, low risk of trips and slips.

Loss of power to Operating theatre.

Risk Grade 1. Consequences, high risk of loss of Patient life.
 

snowhead

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And one question- I can legally supply backup power for the whole site via one ATS?
It's not law that would cover it, it would be Health Service Policy.

Hospitals would always have mulitple backups.
I doubt Health Service Policy would allow a single local source as backup.

The National Health Service Hospital close to where I live has multiple supplies from the local Grid.
Run a 4.9mw gas turbine driven Combined Heat and power generator 24/7 and export when over producing.

Probably have other localised backups as well.

 
OP
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Cookie

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So what would mandate multiple ATSs?

Anyone have a single line of an actual UK hospital?
 
OP
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Cookie

Regular EF Member
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The level of Risk of an electrical supply failure causing harm to Patients and or the Business.

Example,
Loss of power to Car park lighing .

Risk Grade 4. Consequences, low risk of trips and slips.

Loss of power to Operating theatre.

Risk Grade 1. Consequences, high risk of loss of Patient life.

Thank you, makes sense.
 

Rob

Control System Engineer
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So what would mandate multiple ATSs?

Anyone have a single line of an actual UK hospital?
I doubt actual line diagrams of an in service hospital would be available online. However there may be theoretical ones.

It's a bit of a niche subject.

Can you define what you mean by ATS. I presume alternate supply?
 
OP
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Cookie

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I doubt actual line diagrams of an in service hospital would be available online. However there may be theoretical ones.

It's a bit of a niche subject.

Can you define what you mean by ATS. I presume alternate supply?
Nothing government funded? What, the NHS is gov right? Then they should have single lines out there.

ATS= Automatic Transfer Switch
 

Rob

Control System Engineer
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Nothing government funded? What, the NHS is gov right? Then they should have single lines out there.

ATS= Automatic Transfer Switch
They will have single lines out there, but for obvious reasons, detailing supplies for hospitals are not likely to be available to the public.

In the same way military bases, water treatment plants aren't.
 
OP
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Cookie

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They will have single lines out there, but for obvious reasons, detailing supplies for hospitals are not likely to be available to the public.

In the same way military bases, water treatment plants aren't.

In the US disclosure is mandatory if public money is being used in a bid, renovation or to run the facility.

I'd post a link as an example but the forum won't let me saying its spam.

(*edit- never mind, it went through this time)
 

DPG

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Why the particular interest in the electrical systems of various countrys' hospitals? Seems a bit specific.
 
OP
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Cookie

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I'm still thinking this may be a wind up.

For those wondering about why I'm spinning my wheels on ATSs and dedicated electrical branches-

The NEC requires that hospitals have their critical loads divided among 3 separate branches.

Life Safety, Critical, and Equipment.

Life safety branch is only for lighting (hallway, egress, stair well, exit sign), door openers, fire alarms and emergency communications systems which aid in the evacuation of a hsopital during a fire.

Critical branch is for patient care receptacles (ie ventilators, cardiac EKG, dialysis), operating rooms, task lighting, hall lighting... anything which is deemed essential for keeping people medically alive and executing tasks related to it.

Equipment branch is for OR HVAC, motors, ventilation, medical gas and vacuum pumps, ect. Any large equipment needed in the bare minimum of patient care.

If the essential power system is 150kva and under code mandates 1 ATS, but if the load is over 150kva you need at least 3 ATSs.
 

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OP
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Cookie

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Why the particular interest in the electrical systems of various countrys' hospitals? Seems a bit specific.

In simple terms each has their own rules, often contradictory to one another lol, and with that evidence as to what is best practice and not best practice come reality.


That and the differences themselves are rather enlightening in electrical theory and the code making process for better and for worse.
 
OP
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Cookie

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I'm still thinking this may be a wind up.

And just to address the specifically- Its not a wind up. Keep thinking that, I'll be laughing when you end up with AFDDs because the messengers knowing of the empty fire extinguisher were all labelled wind ups and trolls.
 

Rob

Control System Engineer
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And just to address the specifically- Its not a wind up. Keep thinking that, I'll be laughing when you end up with AFDDs because the messengers knowing of the empty fire extinguisher were all labelled wind ups and trolls.
If you've read BS7671 then you would know they are already part of our regulations.

Not mandatory yet, and certainly a money making scheme.
 
OP
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Cookie

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If you've read BS7671 then you would know they are already part of our regulations.

Not mandatory yet, and certainly a money making scheme.

I know they are. But its steps away from becoming so. The only reason they were created was because the US does not do loop impedance. UL was researching your breakers and RCDs 30 years ago in hopes of creating the same thing here and behold the AFCI. Now they are being sold to Europe as something new when in reality your system is already an arc detection system. Its so messed up I can't even begin to vent my anger.
 

Rob

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Our RCD's and MCB's (Breakers) do not detect arcs.

AFDDs work on entirely different principles.
 
OP
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Cookie

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Our RCD's and MCB's (Breakers) do not detect arcs.

AFDDs work on entirely different principles.
They most certainly do detect arcs, UL actually proved that. In fact the first AFCI in the us was supposed to be a breaker with a 75amp magnetic pickup, but because of inrush tripping an electronic unit was developed. If you knew the history, you'd be outraged.
 

Pete999

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I can't see how UK MCBs will detect arcs to be honest
Nor me, if they could the IET wouldn't be trying to sell the idea of AFCIs to us with the 18th Edition, would they??????
Plus there is some about using them on RFCs that's Ring FCs not Radial FCs
 
OP
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Cookie

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Nor me, if they could the IET wouldn't be trying to sell the idea of AFCIs to us with the 18th Edition, would they??????
Plus there is some about using them on RFCs that's Ring FCs not Radial FCs

An AFDD is money secured for the manufacturer. Come time AFDDs will probably have self test logic, meaning they will lock out every X years and require replacement. Already being done with US GFCIs.


AFCIs got into the NEC because manufacturers (like Eaton) bribed the code making panels and UL. They want to and are grdually doing the same with the IEC through committees.


Manufacturers know electrical equipment is near perfected and cheap, I mean what else is capable of lasting 60+ years? But if you require products through mandates, especially products that will require replacement the financial reward is in orders of magnitude greater then before. Investing millions will give you billions, and investing billions will give you trillions. With millions and billions its not hard to cook up a lie one great enough that most everyone will believe.
 

Carl S

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The UL approved AFCI’s despite not knowing how to test them. They just blindly followed what the manufacturers told them to do. Self test was incorporated from the start.

To add, it’s not in the UL’s remit to randomly test equipment that won’t be compatible with NFPA-NEC codes.
 
OP
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Cookie

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Here is but one of many studies done by UL. This one was so the NEC would allow the first 50 feet of romex (twin and earth) to be protected by a newer US circuit breaker and the rest by a socket AFDD.

Quoted from page 48


As the
empirical analysis had suggested, the statistical analysis concludes that the magnetic trip level needs to
be exceeded by a factor of 1.25 to mitigate the arc within eight half-cycles (Figure 14, left). Furthermore, a
breaker only has a 95% probability of tripping at all during an arcing event if the short-circuit current
equals the magnetic trip level of the circuit breaker. Probability of a breaker trip exceeds 99% only once
the short-circuit current exceeds the magnetic trip level by a factor of 1.25 (since the magnitude of an arc
typically is 80% of the short-circuit current). Therefore, the previous statement about breaker
effectiveness is further qualified by stating that breakers can be effective at mitigating arcing faults,
provided the available fault current can be guaranteed to exceed the magnetic trip level of the circuit

breaker by a factor of 1.25.

You guys already do earth fault loop impedance, (something not mandated by the NEC and unheard of by US sparks), so an arc fault at any point in the circuit will trip your breakers magnetically.

If the fear is that fault current does not exceed 125% of the breaker's magnetic pickup all BS7671 has to do is tweak the loop impedance numbers.

There is simply no need for AFDDs.

And I know someone will say "what about serial arcs" and I will reply AFDDs have little hope with serial arcing for what is another lengthy con saga.
 

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marconi

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Dear Cookie, may I suggest you start a new post on the subject of AFDs? It is 'out of sight' to most EF members under the present topic title. That way more EF folk will be able to read and comment on this interesting topic, some of which will have first hand experience of deciding on their use and their effectiveness once installed in different settings. If you do please copy over the Breaker Mitigation report.
 
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