Thread: buying first mig - have 20 amp fuse but 10 amp plug outlets in shed..

Originally Posted by woodmama

So I was wondering, because of the bigger plug on the 15 amp welders - can i somehow modify something safely so that i can use a 15 amp welder?. I'm assuming that 20 amp allowance (according to the circuit board) is safe enough for a 15 amp welder.
cheers

I believe so though I'm not a pro so you take responsibility for whatever you do .. It sounds like it might be as simple as going into a hardware store and buying a 15A wall socket and substituting it so you can use it natively. Sounds like someone spec'd the higher power requirements in the shed (smart, 10/15A ccts shouldn't exist in a shed) but skimped on the actual outlet.

Originally Posted by woodmama

As you can imagine being a woman and walking into welding shops can sometimes be a daunting experience - I am slowly learning how to speak Weldanian lol.

Makes no difference. I'm a guy but it's the same thing when I walk in. They can smell a newb a mile away :lol:

gidday mamma
sometimes people change circuit breakers without knowing the actual reprocutions.. i sugest that if you know a sparky ...give him a call. to have a 15 amp power point in your shed it shold be on a dedicated cuircuit running 4mm wire. its easy to find out if that is what you have. eg is the current curcuit suplying power to multiple power points in you shed? if so then i would recommend not running a big amp welder off this circuit. chances are that the wireing in the wall is only 2.5 mm. this size wire will heat up while welding. there is a difference between haveing a 20 amp circuit and having a 15 amp power point. a 20 amp cuircuit will let you run multiple items up till a total of 20 amps is drawn. but not all at once on 1 lead. yes it gets confusing but belive me ...never play with power unless you are an expert in the feild. i hope this helps. just a note to that ..i have had a dedicated power point put in my shed and the differance to the welding prosess was amazing. .. with the extra availibility of the power made a huge diffferance to my welding results too.
good luck with taking on welding...i'm sure you will have alot of fun...

Hi Woodmama

Originally Posted by montiee

I believe so though I'm not a pro so you take responsibility for whatever you do .. It sounds like it might be as simple as going into a hardware store and buying a 15A wall socket and substituting it so you can use it natively. Sounds like someone spec'd the higher power requirements in the shed (smart, 10/15A ccts shouldn't exist in a shed) but skimped on the actual outlet.

I would most certainly NOT follow the above advice as it would cause your current installation to be illegal (regardless of who does the "change over") and possibly dangerous.

Originally Posted by glen boulton

... to have a 15 amp power point in your shed it shold be on a dedicated cuircuit running 4mm wire.

Not necessarily so, but Glens advice in general is good - basically to have a 15 amp GPO you need a separate circuit, you can't just tack on a 15 amp GPO onto an existing circuit (or replace a 10 amp with a 15 amp).

i did ask for a dedicated point for welding and i asked for heavier wire to be used on this cuircut and this was done by a licenced electrican. but stick with the origanal advice and get an expert to do it. 24 years in the building trade and i have seen the results of "home remedys". this forum should be for advice only and should never be taken over a qualified expert in the feild that has inspected your job first hand... there are so many contributing factors that effect the power draw on a curcuit it would be imposible to see them all from a computer table...simple things like is the shed on its own circiut from the main board.... if so is that power feed big enough to take the extra load.... there are many other things like this that matters. so i will echo my sugestion to get an expert to do a site visit and check it out. it may cost you money but this value is overshaddowed by any other property loss from fire or even loss of life the cheeper alternative. a quote costs you nothing..

thank you for your replies back, you all raised really valid points.
I had wondered too montiee about whether it might just be able to switch face plates to a 15 amp point, but then I became worried because there is a double power point in the shed.

I then had a similar thought to Glenn's - could it be that the 20A circuit board switch takes a TOTAL of 20A rather than individually i.e. 2 x 10A plugs - which might explain why the 10 A socket cover was used and if it was like that then it might involve lighter wiring .

I'm not sure - I would think it would be 20A fuse per plug as when had a look at the other circuits, they had lower amps e.g. 6A fuse for lights.

If i carefully removed the cover off the shed powerpoint (with power off of course) - would i then be able to confirm if it was 20A per socket? - is there any labelling/marking of wiring i can look at to confirm?. I certainly wont be attempting anything more than that but if its just a simple inspection then I dont want to unnecessarily go calling out an electrician if I can get away with doing it safely myself.

thanks again for the info...and you are right vernonv - safety first...ALWAYS! You cant weld when you are toast!

Woodmama,
If you have have more than one 10 amp GPO in your shed on the one circuit then you most certainly won't be able to change it over to a 15 amp GPO, regardless of the wiring or circuit breaker used. Most 15 amp GPO circuits normally only have only 1 outlet and are supplied by a 20 amp breaker and at least 2.5mm2 cable ... but this information is very general and it depends on your particular installation as to how it would be setup.

It would be pretty safe to say that if you want a 15 amp outlet them you will need to get another dedicated circuit installed.

there is no way of telling by simply "looking" at it unless the wiring is all exposed and you can do the chase the spaggetti thing. even then if you miss somthing ....then not good. get an electrican out as there is no charge for a quote. he will tell you if it is a part of a series or a dedicated curcuit. hope this helps

Originally Posted by woodmama

I then had a similar thought to Glenn's - could it be that the 20A circuit board switch takes a TOTAL of 20A rather than individually i.e. 2 x 10A plugs - which might explain why the 10 A socket cover was used and if it was like that then it might involve lighter wiring .

Doesn't usually work like that though. I mean you don't have individual 10A circuits for every single powerpoint in your house I can guarantee you. You probably have a number of 10A outlets running off the one 15A fuse. It's up to you to load manage in the house. Exceed the 10A rating and the fuse will trigger saving your wiring. Same deal in the garage. Use the welder then don't have any other high power appliance running on that 20A circuit else the fuse will trigger.

If the correct guage wire has been used for the 20A fuse then no harm should result to the wire and the fuse will trip by the time it has. If someone installed 10A wire on a 20A fuse circuit then that's another issue but then you would have problems running 2x10A appliances anyway from a safety perspective.

Originally Posted by Vernonv

Woodmama,
If you have have more than one 10 amp GPO in your shed on the one circuit then you most certainly won't be able to change it over to a 15 amp GPO, regardless of the wiring or circuit breaker used.

Huh? How does that logic work? If you have a 20A circuit with 2x10A GPO's of course you can replace it with a 1x15A GPO. I'd like to hear your logic why not if you disagree..Don't tell me you think every 10A outlet in your house has an individual 15A circuit?

At no point along the wiring of the 20A circuit should you introduce wire which is meant for 10A circuits even if you have 2x10A GPO's.

Originally Posted by montiee

If you have a 20A circuit with 2x10A GPO's of course you can replace it with a 1x15A GPO.

Yes you can most likely (depending on a few preconditions) replace 2 (or more) x 10A GPO's with 1 x 15A GPO. But you can't replace just one of the 10A GPO's with a 15A GPO (and leave the other 10A GPO's there) you must only have one 15A GPO on the circuit and nothing else.

I'd like to hear your logic why not if you disagree..

It's not about what I think - I'm simply looking at what the standard says. If you don't follow the standard then at the very least your installation will not be legal, and at worst fatal.

Don't tell me you think every 10A outlet in your house has an individual 15A circuit?

No I don't think that ... do you? I'm not sure what you are getting at???

At no point along the wiring of the 20A circuit should you introduce wire which is meant for 10A circuits even if you have 2x10A GPO's.

Yes that is correct - the breaker (assuming 20 amp) must protect the wiring and as such the wiring must be able to handle as least 20 amps.

Originally Posted by Vernonv

Yes you can most likely (depending on a few preconditions) replace 2 (or more) x 10A GPO's with 1 x 15A GPO. But you can't replace just one of the 10A GPO's with a 15A GPO (and leave the other 10A GPO's there) you must only have one 15A GPO on the circuit and nothing else.

This flies in the face of how your house is actually wired.

Originally Posted by Vernonv

No I don't think that ... do you? I'm not sure what you are getting at???

What you seem to be implying is that for evey GPO must be on a separate circuit. That is impossible for any household. You could not fit the number of fuses/circuits in the box. It would be overwhelmingly massive.

Let me ask you a series of simple questions.
1) Do you agree that your house can have more than one 10A GPO on a 15A circuit. For eg sum total could be 30Amax sitting on the one 15A circuit.
Before you say no then you should go have a look at your fuse box and then walk around your house and count the number of GPO's.

2) If yes to (1) what is the difference if you have 1x10A GPO and 1x15A GPO running off the single 20A circuit compared to 4x10A GPO outlets on a 15A circuit. The point is like the house you have an upper limit dictated by the fuse/wire diameter. Overload it and it will trigger. That's one of the reasons why it's there. On a 20A circuit you can happily run up to 15A on that circuit. How you divvy that up is up to you. If you stick on a welder you know that's all that can sit there before triggering the circuit.

Overlapping is part of standard house wiring. The assumption is that most appliances won't use the full circuits capability so you can load it up by having multiple outlets on the one circuit even though their max current draw exceeds the current draw of the circuit they are on since usually most appliances don't draw anywhere near max. On the off chance they do the fuse will trip.

Originally Posted by montiee

This flies in the face of how your house is actually wired.

No it doesn't. You can normally have multiple 10A GPO on one circuit, but depending on how your circuit is configured you may only be able to have 1 x 15 amp GPO on the circuit.

What you seem to be implying is that for evey GPO must be on a separate circuit. That is impossible for any household. You could not fit the number of fuses/circuits in the box. It would be overwhelmingly massive.

No that's not what I am saying, it's what you are reading into it due to you lack on understanding of the wiring rules.

Let me ask you a series of simple questions.
1) Do you agree that your house can have more than one 10A GPO on a 15A circuit. For eg sum total could be 30Amax sitting on the one 15A circuit.

Depending on the circuit config, on a circuit with a 16 amp breaker you can have up to 15 x 10 amp GPO's (this is from memory)

2) If yes to (1) what is the difference if you have 1x10A GPO and 1x15A GPO running off the single 20A circuit.

Nothing, but that is not what we are talking about. Woodmama said she has multiple 10A GPO's in her shed on a 20 amp breaker - you can not legally replace one of those 10 amp GPO's with a 15 amp GPO, unless you remove all of the other 10 amp gpo's from the circuit ... thus leaving 1 x 15 amp GPO on the circuit and that's it.

Originally Posted by Vernonv

No it doesn't. You can normally have multiple 10A GPO on one circuit, but depending on how your circuit is configured you may only be able to have 1 x 15 amp GPO on the circuit.

Can you have 1x15A GPO ad run an external powerboard off it?

That's probably the cheapest way to go about it. Use the welder then once finished unplug it and plug in 4xGPO outlet powerboard. for the normal stuff.
Certainly is a weird regulation where you can run multiple 10A GPO's off a 15A circuit but only one 15A GPO on a 20A circuit. I guess they figured abuse would be more frequent in business if they allowed the same regulation as they do on 10A residential circuits.

Anyone interested see http://www.ess.govt.nz/templates/Mul...____18598.aspx and go to table 1.

Originally Posted by montiee

Can you have 1x15A GPO ad run an external powerboard off it?

Yep, nothing stopping you from doing that.

Certainly is a weird regulation where you can run multiple 10A GPO's off a 15A circuit but only one 15A GPO on a 20A circuit. I guess they figured abuse would be more frequent in business if they allowed the same regulation as they do on 10A residential circuits.

There are ways to get more 15 amp GPO's on the one circuit, but you must use a bigger breaker and/or possibly bigger cable and/or install the cable a certain way (eg ensure that it won't be enclosed in thermal insulation).

When it comes to the wiring rules, things are never simple ... you really need to look at a particular installation to determine what is allowed.