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Commercial Call center sockets

Discuss Call center sockets in the Commercial Electrical Advice area at ElectriciansForums.net

James

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So I have had an enquiry about a large open plan call center with around 150 desks.

Rented office space, each desk has at least 1 pc with 2 monitors.
There is also all the other IT equipment you would expect in a big office.

The office sockets are fed from 2 x bus bar trunking runs under the floor.
Each of these is fed from a 40A RCBO via swa cable.

There are many floor mounted boxes each with 2 x twin sockets that are plugged in to the trunking system that then run the office equipment at the desks. Singles in flexible conduit, steel spiral type.

Problem is the RCBO’s are tripping at random intervals, sometimes in the day and sometimes overnight.

I have logged the current on each circuit for 5 days and found max load in the region of 30A on both circuits with no peak before current drops to 0 (breaker tripped)

All equipment has been recently pat tested and has a clean bill of health.

The obvious diagnosis is that a cumulative leakage from all the IT equipment is tripping the RCBO.

There are 2 ways I am considering dealing with this,
OPTION 1

Split the trunking into 4 runs instead of 2 fed from 4 x 40A RCBO’s
This will probably fix the issue and is the cheaper and quicker option.

OPTION 2
Change the RCBO’s to Standard breakers.
Mark the trunking runs along there length with warning about lack of rcd protection.
Change all the socket outlets to rcd sockets.

This is my preferred option, it would still provide protection to all outlets.
A fault on one socket won’t black out half the office but be confined to that socket only.

What are people’s thoughts?
In my mind, both options comply with regs.
The trunking is not accessible without lifting the floor.
 
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davesparks

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RCD sockets would giv ethe best resistance to nuisance tripping and represent the best option for the customer.
However if they want the cheapest option rather than the best then splitting across 4x feeds might work. However there is no guarantee that this will eliminate the nuisance tripping.

I don't see any need to label the trunking if it isn't fed via an RCD, it doesn't need it and you wouldn't normally expect to find it fed by rcd
 

Pete999

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So I have had an enquiry about a large open plan call center with around 150 desks.

Rented office space, each desk has at least 1 pc with 2 monitors.
There is also all the other IT equipment you would expect in a big office.

The office sockets are fed from 2 x bus bar trunking runs under the floor.
Each of these is fed from a 40A RCBO via swa cable.

There are many floor mounted boxes each with 2 x twin sockets that are plugged in to the trunking system that then run the office equipment at the desks. Singles in flexible conduit, steel spiral type.

Problem is the RCBO’s are tripping at random intervals, sometimes in the day and sometimes overnight.

I have logged the current on each circuit for 5 days and found max load in the region of 30A on both circuits with no peak before current drops to 0 (breaker tripped)

All equipment has been recently pat tested and has a clean bill of health.

The obvious diagnosis is that a cumulative leakage from all the IT equipment is tripping the RCBO.

There are 2 ways I am considering dealing with this,
OPTION 1

Split the trunking into 4 runs instead of 2 fed from 4 x 40A RCBO’s
This will probably fix the issue and is the cheaper and quicker option.

OPTION 2
Change the RCBO’s to Standard breakers.
Mark the trunking runs along there length with warning about lack of rcd protection.
Change all the socket outlets to rcd sockets.

This is my preferred option, it would still provide protection to all outlets.
A fault on one socket won’t black out half the office but be confined to that socket only.

What are people’s thoughts?
In my mind, both options comply with regs.
The trunking is not accessible without lifting the floor.
Just a thought, have you measured the EL from each work station? and what is the cumulative EL causing the RCBO trip? again a thought that you may have to reconfigure the wiring method, could be you have far too many WS per circuit.
 

James

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My thoughts on the trunking are as follows.
It is basically a long run of sockets,
There is nothing stopping someone buying another floor box with standard sockets and plugging it into the trunking.
 

davesparks

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My thoughts on the trunking are as follows.
It is basically a long run of sockets,
There is nothing stopping someone buying another floor box with standard sockets and plugging it into the trunking.
No there isn't, but a person who does that without considering the need for rcd protection beforehand is pretty much guaranteed to ignore any label you have stuck on the trunking.
 

James

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Got to go and do some work for a bit.
Thanks Pete for your thoughts so far
I will have a look this evening and try to get my head round peoples responses.
 

telectrix

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agree with davesparks. option 2 IMO. RCD is not required. to cover your arse you could provide a written RA.
 

Pete999

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No there isn't, but a person who does that without considering the need for rcd protection beforehand is pretty much guaranteed to ignore any label you have stuck on the trunking.
Might pay you to have a look at 7.5 through to 7.6 in the OSG Page 86 to give you some food for thought, this also gives you Regulation number to read, I haven't bothered to look myself but it may be that busbar trunking is not the way to go for IT equipment, I don't know to be honest, I do know however IT circuitry can be a right pain, worth a look at the OSG and BS7671 543.71 201, 203, 204, 205.
201 figures 7.5.3, 543.7.2 hope the info helps.
My last office install was suggested that It must be done as per the install you have.
I changed that after consultation to 2 work stations per radial, in Plastic Dado trunking, 24 work stations in total 20A 30mA rcbos never had any trouble after that change either all wired as 7.5.3 OSG
 
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Andy78

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Would be good to get clarification on 531.3.4 in the 18th which now seems to exclude the use of RCD sockets to BS7288
 
T

The Ghost

only one thing wrong with your conclusion re cumulative leak, it happens overnight.
 
T

The Ghost

Yes maybe they do work at night forgot about that.
 

davesparks

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Might pay you to have a look at 7.5 through to 7.6 in the OSG Page 86 to give you some food for thought, this also gives you Regulation number to read, I haven't bothered to look myself but it may be that busbar trunking is not the way to go for IT equipment, I don't know to be honest, I do know however IT circuitry can be a right pain, worth a look at the OSG and BS7671 543.71 201, 203, 204, 205.
201 figures 7.5.3, 543.7.2 hope the info helps.
My last office install was suggested that It must be done as per the install you have.
I changed that after consultation to 2 work stations per radial, in Plastic Dado trunking, 24 work stations in total 20A 30mA rcbos never had any trouble after that change either all wired as 7.5.3 OSG
Eh? What's that got to do with my point that labels about RCDs are a waste of time?
 

Pete999

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Eh? What's that got to do with my point that labels about RCDs are a waste of time?
Nothing, replied to the wrong thread meant to be for the OP soz dave
 
If you do go down the standard breaker route, make sure you select a curve that will allow all the IT equipment to be powered up at once.

I was responsible for the electrical installation at 1000 seat contact centre. We had a power cut and when the power came back on, all the breakers tripped because the inrush current to all the IT equipment. We had to run around unplugging about half the equipment before we could turn the breakers on without them immediately tripping.
 

James

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Would be good to get clarification on 531.3.4 in the 18th which now seems to exclude the use of RCD sockets to BS7288
It’s a bit of a bugger really, when regs contradict each other.

Think because it’s a first floor office and not domestic, we can probably risk assess our way out of that, even if it is non compliant it can still be done.
The regs do not prevent using other methods it’s just a bigger paperwork trail to prove it has been done as safely as possible.
After all, this has got to work and be safe.
Otherwise a very large online estate agent is going to be pee ing a lot of customers off.
 
T

Toneyz

Have you measured the leakage current? As for the RCD socket does anyone know why it is not in the 18th (I presume that it trips out in the prescribed times) Could this be put down as a deviation?
 

Leesparkykent

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Have you measured the leakage current? As for the RCD socket does anyone know why it is not in the 18th (I presume that it trips out in the prescribed times) Could this be put down as a deviation?
I think it would be a justifiable deviation. After all a deviation is something that isn’t strictly to regs but gives the same level of safety as compliance.
 
I'd suggest a ramp test on the RCDs. It certainly sounds like the issue is leakage rather than overload. Have you done a count on the number of sockets on each ring?
 

Lister1987

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Stupid question from a non-spark; Have you taken into account contractors using the sockets; Cleaners running buffers, Builders running on-site transformers for tools or what have you? In case they have a higher draw than the workstations? Would increase the load no and they may be left permanently plugged in (charging battery if cordless etc)
 

littlespark

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Op mentions everything in the office was PAT tested?
I bet something has sneaked past the tester, if it’s one of those price per test companies.
Looks ok, just sticker it and hope for the best
 

Pete999

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Op mentions everything in the office was PAT tested?
I bet something has sneaked past the tester, if it’s one of those price per test companies.
Looks ok, just sticker it and hope for the best
Surprising how many office staff bring their own appliances in from home, heaters, fans, coffee makers, kettles seen it all in my time, even found Sex toys spirited away in desks, and before you ask, we, all of us have a quick squint if the place is empty don't we??
 

GBDamo

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ooh, RCD sockets again, whoopie.:bananas:
 
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