UK Blown 13amp fuse on extension lead

[WILLIAM EASON]

I am using a 160watt-200watt multi uv tube stand alone sunbed,When the 2 power leads (plugs protected by 2x13amp fuses) plugged into a double wall socket (protected 32amp circuit breaker)the sunbed works as it should,When an extension cable with one plug top (protected by 1x13amp fuse)and 1xdouble socket is used the sunbed works for 4 mins then the 13amp fuse on extension cable plug top blows ,Can anyone explain why the 13amp fuse does not blow immediately when first switched on,

 

[nicebutdim]

160W-200W

Is this per tube? If so, how many tubes?

 

[James]

Quiet Simpley, the device uses more power than can be supplied by a 13A plug.
therefore the manufacturer has put 2 separate plugs on it to share the load.

 

[WILLIAM EASON]

160W-200W

Is this per tube? If so, how many tubes?

Well done it is so obvious now you have explained it’s per tube and it’s 24 tubes so that explains why the single 13amp fuse blows but why does it not blow immediately but works for 4 mins then blows ,sorry not up on theory of how uv tubes function,ps:-All 24 tubes are switched on simultaneously.

 

[nicebutdim]

It's potentially running slightly over the rating of a standard double socket.

Presumably this sunbed has a rating plate somewhere on it? It would be helpful if you could provide details from it or, even better, an image of it.

I would assume that inrush current from the tubes isn't sufficient to blow a 13A fuse instantly, but load of 3.8-4.8kW explains why it doesn't hold for long as you'll be drawing somewhere between 16.5A and 20.85A.

 

[WILLIAM EASON]

It's potentially running slightly over the rating of a standard double socket.

Presumably this sunbed has a rating plate somewhere on it? It would be helpful if you could provide details from it or, even better, an image of it.

I would assume that inrush current from the tubes isn't sufficient to blow a 13A fuse instantly, but load of 3.8-4.8kW explains why it doesn't hold for long as you'll be drawing somewhere between 16.5A and 20.85A.

Rating plate has max 5kw
If this is not enough info I will send an image

 

[WILLIAM EASON]

It's potentially running slightly over the rating of a standard double socket.

Presumably this sunbed has a rating plate somewhere on it? It would be helpful if you could provide details from it or, even better, an image of it.

I would assume that inrush current from the tubes isn't sufficient to blow a 13A fuse instantly, but load of 3.8-4.8kW explains why it doesn't hold for long as you'll be drawing somewhere between 16.5A and 20.85A.

I understand the why and the how thanks to your explanation .
Thanks again for your help,The next time somebody asks me why this happens I’ll be able to sound extremely intelligent,lol

 

[nicebutdim]

Rating plate has max 5kw
If this is not enough info I will send an image

That's about right - I was working on max 4.8kW @230V.

Take a look at a graph detailling operating characteristics for BS1362 fuses.

At just over 20A I'm surprised it blows so quickly. This sort of overload is more likely to generate sufficient heat to damage plug, socket and cable, but I wouldn't have expected the fuse to blow within 4 seconds. It's a fairly dangerous set up.

 

[Mike Johnson]

Also connecting both plugs into a double socket is overloading the socket.

 

[DPG]

5 kilowatts of UV - that can't be good for you surely??