Thread: 15amp welders on 10amp circuits

Originally Posted by A Duke

"Rules are for the obedience of fools and the guidance of wise men."

While I agree with the sentiment, I would suggest the reason we now have so many "rules" is because of all the fools out there - if people didn't do stupid things, we wouldn't have all these "do-gooders" trying to protect them (let Darwin take care of them I say). It's just unfortunate than fools often take innocent people with them.

Actually I believe the rules are there chiefly to protect the innocent third party, more so than the backyard sparky. If someone does something stupid and burns down their house or shed, that's their problem. It's when they do something stupid and then sell the house, shed or welder to some other poor bastard who then has their house or shed burn down that I feel sorry.

Interestingly that quote was no doubt from a person (Douglas Bader) who considered himself to be a wise man, and there is another quote that goes "A fool thinks himself to be wise, but a wise man knows himself to be a fool"

Must be that time of the month again, cos I reckon this question comes up about once a month.

Another of my favourite sayings
"Every fool proof device just breeds another type of fool."
Undoubtedly the guy who put a bigger earth pin on a 15 amp plug to stop it being plugged into a 10 amp socket thought it was fool proof and probably was at the time, for about 10 minutes..
Regards

I don't think it was meant to be fool proof. It was meant to make it obvious to any idiot that it shouldn't be connected to a 10amp supply. It's like the red dot on the hot tap. It doesn't stop you from sticking your hand under it, but if you're stupid enough to do it, you've no-one to blame but yourself.

Ive seen many 15 amp welders run on 10 amp power, some people just make a short lead that goes from a 15 amp to a 10 amp plug, They run fine but if it keeps tripping the breaker then u probably shouldn't do it.

One point perhaps missed here, a 15 amp welder WILL run better on a 15 amp circuit. Skinny wires will limit the amount of current entering your welder. A thicker conductor will carry more current, just as a bigger pipe will carry more water.

Yes, a thinner conductor will heat up more. Heat has an inverse relationship with conductivity.

Safety concerns aside, it will choke your welder so that it works harder, especially at full noise, limiting duty cycle and shortening the life of your gear.

Regarding rented premises- is your landlord unapproachable? If you offered to 'improve' his/her property without it costing him/her a cent would he say no?

A 15A circuit is commonly run with the same 2.5mm cable used for 10A circuits, so there's no difference in circuit impedance.

Originally Posted by RustyArc

A 15A circuit is commonly run with the same 2.5mm cable used for 10A circuits, so there's no difference in circuit impedance.

Mine run 4mm. I wanted 6mm but my sparky talked me out of it.

Originally Posted by RustyArc

A 15A circuit is commonly run with the same 2.5mm cable used for 10A circuits, so there's no difference in circuit impedance.

Except that there is normally only one socket on a 15 amp circuit, whereas there could be 10 or 20 on a 10 amp. Just think of all those joins/connections, lets hope that they are all spot on, as you are now possibly running the circuit at 150% of it's design capacity.

Originally Posted by Vernonv

Except that there is normally only one socket on a 15 amp circuit, whereas there could be 10 or 20 on a 10 amp. Just think of all those joins/connections, lets hope that they are all spot on, as you are now possibly running the circuit at 150% of it's design capacity.

You're not though - you're running the individual socket at 150% of it's design capacity, but the circuit is designed to carry a load up to 16A (despite all the joints), and commonly does - think of having a couple of heaters plugged into the same circuit in winter.

Think of it this way:

A single GPO is rated to 10 amps.
A double GPO is rated to 10 amps per socket outlet.

Total possible draw off a double GPO is therefore 20 amps, with the only thing limiting it being the typically 16 amp breaker.

The reason for the larger earth pin on a 15 amp socket is to specifically prevent it being used on a standard circuit as there would be a much higher chance of nuisance tripping occurring - which is something that might encourage the householder to 'have an attack of the stupids' and use the next size up fuse wire, therefore defeating the goal of circuit protection.

It's not a "Danger, danger Will Robinson, the earth conductor is too small to successfully carry a fault current!" situation - in case anyone hasn't noticed, the earth on both 4mm and 6mm twin and earth is 2.5mm, which is the same size earth you'll get with the 2.5mm t&e used for domestic power wiring.

Originally Posted by RustyArc

You're not though - you're running the individual socket at 150% of it's design capacity....

Well that's ok then. My comment was directed at your suggestion that the circuits (and the impedance of said circuits) are the same - which at the very least in a physical sense is not correct.

Originally Posted by Master Splinter

It's not a "Danger, danger Will Robinson, the earth conductor is too small to successfully carry a fault current!" situation

I don't believe that anyone has mentioned that as a reason for 15amp circuits (but would be happy to be corrected).

I'm all for for people doing what ever the hell they want (including their own wiring) as long as they don't adversely effect anyone else and where applicable they do it to a recognised standard.

Hi guys,

I think we are pretty lucky in this country to have such high standards, this of course takes the stress out of living that you might have if you lived on this street!

Cheers...Oddjob1