> ‘The use of any electrical device in a magazine can initiate the most sensitive EEDs.’
Hmm.
I feel a gentlemens’ wager coming on. I’ll put a bottle of Bollinger on you showing this happen, at the next AGM.
You bring the ‘most sensitive’ EED, I’ll bring a 5 watt UHF radio, which may be placed, on transmit, anywhere you wish.
Game on? 🙂
The serious point I’m making is that ‘compliance with regulations’: this Standard – that Mark – and so on – often has no basis in practical reality.
It matters because sometimes over-zealous enforcement of regulations, often without true understanding, can lead to a reduction in safety.

Hi Nigel: I too have fond memories of the ‘Green Book’ (That’s the Explosives Act 1875 to the younglings).

All that stuff about painting exposed ferrous metals – with cork chips mixed goodly and thick – and so on, and the fetish about rubber footwear was nothing to do with RF, for the unassailable reason that portable radios hadn’t yet been invented.

It was (is) all about not creating sparks inside a magazine. That’s still a good idea, but remember when the 1875 Act was first written it was almost exclusively about gunpowder. I agree that avoiding sparks in a BP mag is a spectacularly good idea. But again all this obsession with not having an exposed screw head in, for example, a modern store full of metal ammo cans containing HE ammunition or SAA, persists.

And much of the Green Book’s reference to ‘artificial light’ meant oil lamps, or candles on miners’ hats!

Inherently safe electrical installations? Good idea, but again nothing to do with RF. A halogen or metal halide lamp which bursts on failure and showers hot glass everywhere (I’ve seen both) would indeed be unfortunate. As would a cheap switch which sparks on operation and is open to atmosphere.

But the latter is more important in places where there are explosive atmospheres (eg flammable gas, hydrocarbon vapour, fine dusts.)

And once again there is often confusion. In this case between ‘explosive atmospheres’ and bulk, non-dusty explosives kept in boxes. Time and again I have had such exchanges of views with enforcing authorities, many of whom have read all the books, but don’t understand WHY the regulations are there, and therefore can’t sensibly use discretion based on actual experience of practical situations.

I have on one occasion been forced to abandon safe practice because it was deemed technically non-compliant, replacing it with something which was potentially dangerous, but which was compliant. So that’s OK then.

Hi Phil – you mention PETN dust from det cord. Are you sure? I have never used a PETN cord which has any possibility of creating airborne dust, no matter how roughly it was cut and shaken about (and competent operators wouldn’t do that anyway).

Dry PETN powder is way too sensitive to be loaded loose into anything. PETN cord includes a considerable amount of wax desensitiser for safety, which has the secondary effect of causing any spilled powder to clump up and fall to the floor. And no one should be unpacking or cutting cord anywhere near a magazine anyway.

One then has to ask about the wisdom of an electrical device introduced into an explosives store, especially as my ancient memory recalls something on this line in the good old and now deceased “Green Book – Guide to the Explosives Act 1875-Explosives Act 1923.
Whilst I accept virtually all of the Green book was thrown out with the bath water
P162 (m) talks of allowing artifical light into a carriage or boat containing explosives – though it doesn’t mention Store!
What I am trying to suggest , and I am not doing it very well, is that I suspect that much hypothetical and apocryphal credit has been attached to issues claiming them as fact when in fact when examined are not in reality fact.!!
Certainly common sense should decree that any unshielded device capable of emiting RF or electro mechanical signal. Should NOT be used in an explosives magazine.

Unfortunately a lot of this stuff has got into the literature and is now quoted all over the place without consideration of real risks.

Sure, if detonator wires are unwound, and extended as a perfect dipole antenna, or a large electric detonator circuit forms a giant aerial on the ground, then you blast the area with hundreds of watts from an HF set, or powerful microwave radars, then maybe; but devices as stored, with coiled wires, and piddly little hand-held transmitters? No way. It’s nonsense.

Remember that we live surrounded by electromagnetic radiation all the time: the commercial radio mast up the road might well be providing more RF field strength that your iPad, and dets don’t keep going off in your hand, do they?

Please don’t think I’m confusing this with stray currents, as that’s very different. I am certainly very uncomfortable using EEDs if there are overhead HV wires about, or an electric storm threatens.

As always, it’s important not to be distracted from real risks by imagined ones.

We do not store any electric dets and only use nonel type down holes and surface, boosters and a bit of cord non of which are susceptible to electronic emissions from iPad (ok we have to take care with nonel tube and static). We are probably going to trial electronic type dets in the future and will review use of the iPad when we do so.

Good point as well about WIFI Jamie, would not use a WIFI enabled iPad. We have a little office in our magazine compound and would store the unit in there, not in the magazines.

The most important thing would be to ensure that the iPad does not transmit a signal, either Wi-Fi or GSM (GSM-capable iPads are likely asking for trouble), so the iPad definitely should be in ‘Aircraft’ mode, and there should be strict protocols for checking this.

To mitigate problems further, I’d also recommend a hard case to protect the iPad from explosives residue, which can be kept at or near the store for just that purpose. If you really wanted to be safe, I guess a case with a micro mesh incorporated to act as a form of Faraday cage would further reduce the risk of stray currents. You’re then left with potential electrostatic discharge as you use the iPad screen, which can be removed in the usual ways.