This is probably a dumb question!

[pauld]

Hi Guys! New round here, but thought I would jump in on this one... I know a thing or two about electrics! You will probably find that you could pull 20amps through a 13amp plug with 13amp fuse for quite a while... don't have the disconnection time graph to hand for 13amp fuse, but you will probably find you can pull 20amp for about 600ish seconds... that said, it is a bad idea! The plug and socket have only been designed to supply the 13amp load, while they will be ok with a bit more for a while, they will start to get hot, and could potential catch fire! Much better to get a dedicated supply installed, that is protected with the correct breaker/fuse, and also RCD protected. Something like one of these is what you want: http://www.tlc-direct.co.uk/Products/GW240slash32slash3S.html

Thanks
Paul

PS.... hoping to get my first MIG soon!

 

[malcolm]

Thanks for posting that. I'd assumed a 13 amp fuse would blow somewhere near 13 amps after 600 milliseconds not 600 seconds. The plugs do seem to get overloaded (fuse mountings particularly) and they need replacing quite often.

These modern trip switches seem much more predictable. Got a 40 amp one for the TIG, and had to go D rated to stop it tripping from in-rush current. Trips seem to worry about what's happening over a 100ms time period. Ought to organise using the circuit for the MIG too.

 

[Bigjoe]

Hi PaulD,
I was just asking the question in theory,i wasnt planning to try it,thanks for the link tho,what cable would i need to get to install one of those?

Many thanks

Joe

 

[pauld]

Tricky that without knowing more of the circumstances of the install etc... there are a whole load of things to take into consideration! Like, how long the cable is from the CU (consumer unit/fuse board) to the outlet.... what sort of total load you are going to have on the cable etc.... you mentioned about having a workshop built, so I am guessing you are going to have to run a new power feed to that, the install of this outlet would probably come as part of that work. Given that it is going to be in a workshop, and you will probably be "swinging" lumps of metal around, I would think you need to look at some sort of mechanical protection for the wiring.... so, that gives two real options, either metal conduit with singles running in it, or SWA cable (Steel Wire Armour). I would probably go for SWA I think. For a 32Amp outlet you are looking at something like 4mm2 cable, but depending on distance from main supply to the house etc you might need bigger to comply with all the regulations etc (voltage drop, resistance of cable etc)... You are probably best getting an electrician in to advise as I can't really give a hard and fast opinion without seeing what you are trying to do and take measurements etc.

What other nice "toys" are you going to have in your workshop?

Ta
Paul

 

[Bigjoe]

Hi Paul,
Im yet to finalise exactly where my workshop will be,as to what toys its going to be a multi-use workshop as i am self employed stained glass artist,but currently use use part of a friends furniture workshop but space is tight.
Welding/fab toys will be a mig welder (16A) and a pillar drill (at first) everything else will be cordless/manual operation,and glass work wise will be a kiln eventually everything else will be 13A power and also lighting etc.

I might get a friendly local electrician that i know to have a look at my requirements and advise me accordingly.

Joe

 

[Masked Marauder]

Just found out the induction motor I have been running from my cooker socket runs at 14 amps when running and nearly 20 amps on start-up. I really think a dedicated 20 amp socket is on the cards!

 

[pauld]

the comment I read somewhere on this site about not using extension leads if possible is related to this topic as well. I presume the reason that not using extension leads is recommended is power loss that is suffered when using them. In any cable there is a voltage drop due to the resistance of the cable, this drop is a related to the cross sectional area of the cable and the current being pulled through it. As the cross sectional area increases, the resistance drops, and hence the voltage drop. For 2.5mm2 cable the voltage drop is something like 18mV/A/m.... so if pulling 20Amps you would have a voltage drop of 0.36volts/metre of cable... this would soon add up and give a loss in power.... For 4mm2 cable the voltage drop is 11mV/A/m... 6mm2 cable is 7.3mV/A/m. So, if putting in a dedicated feed for your welding equipment, you want to keep the cable run as short as possible... and think about the size of cable you use and calculate voltage drop! Downside is that bigger cross sectional area of cable is of course more expensive!