Unfused 13A plugs on mobile X-ray machines

[Andrew Gabriel]

Came across this, and thought other readers here might be interested.

[spuorgelgoog]

Presumably as the plug is not BS1363 compliant but is intended for use in a BS1363 socket, it's an immediate PAT fail?

I don't know how momentary or large the surge loading is but is there a risk of damage to socket contacts, particularly on switched sockets (switch contacts) and uneven ring loading?

Owain

[Martin Brown]

The current draw is mostly inside the safe envelope except at the instant when the Xray tube fires when there is a ~30A current recharge pulse for a few cycles. Evidently it is long enough to make a normal 13A fuse blow but not long enough to be a threat to a ring main.

The protection offered by UK fused plugs is largely illusory. They will survive 2x their nominal load for ~10 seconds and 150% of nominal for a very long time making the plug get uncomfortably warm!

You have to wonder why to be UK code compliant the the red plugs could not use a slow-blow 13A fuse in series with live (good for ~10s @ 30A).

[Rick Hughes]

wonder if all those people who have welders that won't run on 13A know about these. They have initial surge current that 'can' take out a 13A fuse (on high setting) but once the arc is established the current is much lower.

Or perhaps the workaround of wrapping tin foil from cigarette pack around the fuse is still used.

[DerbyBorn]

Rick Hughes wrote in news: [e-mail]:

Just don't use an extension lead then!

[meow2222]

I assume they cost silly money. Wouldnt be surprised at £50 each.

NT