The company I am working for at the moment has a radial circuit for their
server room (Small basement)

I had to shutdown the three servers & UPS yesterday, as I was installing an
additional comms card to the UPS.

When I turned the UPS back on (Loaded with a router, 24 port switch,
firewall and a monitor) it tripped its breaker.

I then realised the breaker is only rated at 16Amp
should this be 20A (As per normal radials?)

Would this indicate all the electrics should be checked for other problems?
(There doesn't seem to be any RCD's for anything either, just 100A isolators
in the two CU's)

This is in an office, would there be any requirement for having RCD's?

Sparks...

The company I am working for at the moment has a radial circuit for their
server room (Small basement)

ISTR something about load problems when several switch mode power supply
machines are switched on at once, and needing to over-rate the circuit
protection accordingly - `fraid I can`t be any more specific than that
though :-}

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In article ,
"Sparks" writes:
The company I am working for at the moment has a radial circuit for their
server room (Small basement)

I had to shutdown the three servers & UPS yesterday, as I was installing an
additional comms card to the UPS.

When I turned the UPS back on (Loaded with a router, 24 port switch,
firewall and a monitor) it tripped its breaker.

I then realised the breaker is only rated at 16Amp
should this be 20A (As per normal radials?)

There may be some reason it's 16A. It might be possible to
increase it and/or change it to a type which will allow a
larger switch-on surge through, but not without inspecting
the circuit.

Would this indicate all the electrics should be checked for other problems?

They should anyway. Most large companies I've worked for have
a building test done once every year or two. Probably should
be done at least every 5 years. It's part of an employer's
responsibility to ensure they provide a safe workplace.

(There doesn't seem to be any RCD's for anything either, just 100A isolators
in the two CU's)

This is in an office, would there be any requirement for having RCD's?

No. I only install RCD's on computer supplies in environments
where engineering work is routinely being performed, i.e. opening
up the system and working inside them.

--
Andrew Gabriel

Andrew Gabriel wrote:
In article ,
"Sparks" writes:

The company I am working for at the moment has a radial circuit for their
server room (Small basement)

I had to shutdown the three servers & UPS yesterday, as I was installing an
additional comms card to the UPS.

When I turned the UPS back on (Loaded with a router, 24 port switch,
firewall and a monitor) it tripped its breaker.

I then realised the breaker is only rated at 16Amp
should this be 20A (As per normal radials?)


There may be some reason it's 16A. It might be possible to
increase it and/or change it to a type which will allow a
larger switch-on surge through, but not without inspecting
the circuit.

I seem to recall we had to have the breaker on our UPS changed from a B
to a C type because of the start-up surge

Would this indicate all the electrics should be checked for other problems?


They should anyway. Most large companies I've worked for have
a building test done once every year or two. Probably should
be done at least every 5 years. It's part of an employer's
responsibility to ensure they provide a safe workplace.

I think the inspection intervals are specified in the OSG to the regs.

"Andrew Gabriel" wrote in message
...
In article ,
"Sparks" writes:

I then realised the breaker is only rated at 16Amp
should this be 20A (As per normal radials?)

There may be some reason it's 16A. It might be possible to
increase it and/or change it to a type which will allow a
larger switch-on surge through, but not without inspecting
the circuit.


But is a 16 amp radial circuit for sockets acceptable? Garage CUs usually
come supplied with both a 6 amp and 16 amp breaker and it is quite obvious
what their uses are intended for. Recently during a test of one of my
rewires, the NIC guy I use made me change the 16 amp MCB for a 20 amp MCB in
the garage CU.

Adam

"Lurch" wrote in message
...
On Sat, 04 Dec 2004 19:52:27 GMT, "ARWadsworth"
strung together this:

But is a 16 amp radial circuit for sockets acceptable?

There's no requirement, it's just a recommendation I suppose. You can
have socket outlets on 3A or 50A circuits, as long as the cables and
accessories are correct.

That is what I thought.

A history question. As I see far more 15 amp fuse wired radials than 20 amp
radials, did something change in the regs years ago to alter the rating of
radials from 15 to 20 amp? The usual fuse wire is 5, 15 and 30 amps wound
onto a piece of cardboard but I occasionally find 20 amp fuse wire on some
of these cardboard dinosaurs.

Adam

On Sat, 04 Dec 2004 22:48:04 GMT, "ARWadsworth"
strung together this:

A history question. As I see far more 15 amp fuse wired radials than 20 amp
radials, did something change in the regs years ago to alter the rating of
radials from 15 to 20 amp? The usual fuse wire is 5, 15 and 30 amps wound
onto a piece of cardboard but I occasionally find 20 amp fuse wire on some
of these cardboard dinosaurs.

Think it was more that 15A suited some of the long runs of cables,
likely appliances and size combinations in the olden days. I think 20A
became more popular with the advent of more\higher rated appliances,
and then ring mains became the norm.
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A.C.S. Ltd
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John Stumbles wrote in message ...

I seem to recall we had to have the breaker on our UPS changed from a B
to a C type because of the start-up surge

Best idea, will much improve matters.

But dont assume you can switch power on to a circuit heavily loaded
with IT equipment, beyond a certain loading you'll always need to
reduce load, energise circuit, then switch loads on. IT kit uses
SMPSUs which take a heavy switch on surge.

NT

Think it was more that 15A suited some of the long runs of cables, likely
appliances and size combinations in the olden days. I think 20A became
more popular with the advent of more\higher rated appliances, and then
ring mains became the norm.

Was'nt it commercial/industry that always used 20A for radial
circuits and its filtered down ?

Dave

--

Some people use windows, others have a life.

On Sun, 05 Dec 2004 08:15:31 +0000, Dave Stanton
strung together this:

Was'nt it commercial/industry that always used 20A for radial
circuits and its filtered down ?

Could be. I only started in '95 as an apprentice so can only go back
that far on personal experience! Doesn't Europe have a history of
using 20A radials everywhere as well?
--

SJW
A.C.S. Ltd
Please reply to group or use 'usenet' in email subject

"Lurch" wrote in message
...
On Sun, 05 Dec 2004 08:15:31 +0000, Dave Stanton
strung together this:

Was'nt it commercial/industry that always used 20A for radial
circuits and its filtered down ?

Could be. I only started in '95 as an apprentice so can only go back
that far on personal experience! Doesn't Europe have a history of
using 20A radials everywhere as well?
--

SJW
A.C.S. Ltd
Please reply to group or use 'usenet' in email subject

Where are A.C.S. Ltd ??

On Sun, 05 Dec 2004 09:00:40 GMT, "Stephen Dawson"
strung together this:

Where are A.C.S. Ltd ??

Everywhere, soon to be nowhere.
--

SJW
A.C.S. Ltd
Please reply to group or use 'usenet' in email subject

"ARWadsworth" wrote
| A history question. As I see far more 15 amp fuse wired radials than
| 20 amp radials, did something change in the regs years ago to alter
| the rating of radials from 15 to 20 amp?

It used to be one 15A socket per 15A radial circuit, ie no allowance for
diversity. Smaller appliances would have been on 5A plugs.

With the introduction of 13A plugs, meaning the same circuit is used for
large and small appliances, diversity comes into play, allowing more than
one socket per circuit. And 2.5mm cable is adequate for 20A in most
circumstances (the 20A radial standard circuit specifies a *minimum* of
2.5mm, as indeed does the standard 32A ring circuit).

One reason for the design of the 30A ring circuit was the idea that two
existing 15A radials could be used as the basis for a new ring circuit.

Owain

Could be. I only started in '95 as an apprentice so can only go back that
far on personal experience! Doesn't Europe have a history of using 20A
radials everywhere as well?

Yes they do, forgot that.

Dave

--

Some people use windows, others have a life.

2A sockets were common too, for anyone that doesnt know. There were 3
pin 15A, 5A and 2A, and the even older 2 pin 5A non-polarised plugs
/sockets. All these were used together on the same install.

In practice, the round pin system was a mess. With the penultimate one
I used, the appliances had whatever size plug would fit in the nearest
socket, regardless of ampacity, and home made adaptors consisting of 5A
plugs to 15A sockets were aplenty, as were christmas trees of adaptors.

The last one I used was all wired in 2 core wire, no earth at all.


NT