Is this wrong?

[Sparks]

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...

[Colin Wilson]

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 :-}

[Andrew Gabriel]

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.

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.

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.

[John Stumbles]

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

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

[ARWadsworth]

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]

On Sat, 04 Dec 2004 19:52:27 GMT, "ARWadsworth" strung together this:

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.

[ARWadsworth]

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

[Lurch]

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

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.

[N. Thornton]

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

[Dave Stanton]

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

Dave

[Lurch]

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

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?

[Stephen Dawson]

Where are A.C.S. Ltd ??

[Lurch]

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

Everywhere, soon to be nowhere.

[Owain]

"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

[Dave Stanton]

Yes they do, forgot that.

Dave

[bigcat]

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