# A question about workshop electrics for my welder (newb)



## Splitlight (26 Aug 2022)

Hi all,

I have just bought my first welder & am looking forward to using it. However, I don't really understand electrics very well so thought I'd post here for some advice before I contact an electrician to get the power supply set up (based in the UK).

I got a Hyundai MMA-160, for no reason other than I wanted a basic stick welder & the reviews online seemed good. It's described in the instructions as a 'DC inverter MMA welder'.

The instructions say these are the technical specifications:

Model | MMA -160

Rated input voltage | 1P AC 230V, 50Hz

Rated input power (KVA) | 6.8

Rated input current (A) | 29.6

Rated output current & voltage | 160A/26.4V

Output current (A) | 20~160

No-load voltage (V) | 67 +/- 5

Rated duty cycle (%) | 25

Eficiency (%) | 85

Power factor (cos *θ* ) | 0.73

Protection class | IP21S

Insultation class | F

So.. based on this information what should I do in terms of workshop electrics? My amateur knowledge of UK electrics is that domestic supply is 230V so the welder should plug in fine to the garage socket. But do I need to consider changing it somehow to accomodate the power requirements of the welder? I've heard of ceeform type outlets, is this something I'll need?

Also, the supplied power cable is quite short (estimate under 2 metres), but I would like to weld in the garden so I don't need to worry about fumes. Is there any known problems with just buying a very long cable (say 10-15metres) and it affecting the welder? I've heard of things like voltage drop over a distance but don't really understand it.

I essentially know nothing about electrics so any tips would be appreciated. Thanks


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## sawtooth-9 (27 Aug 2022)

That mother sucks amps !!
Most ( even the older stick welders ) used to run off a 15 amp source.
Suggest you get some advice on this one.
You would probably need to run 6 mm cable to provide that amperage.
As for running a longer lead to the garden - you may need to run up to 10 mm cable as an extension - depending on the distance.
There are many inverter welders that draw far less current , not sure what your intended use is - building bridges ?


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## Myfordman (27 Aug 2022)

As you admit no electrical knowledge and a number of technical questions need resolution then you need the services of an electrician to assess the problem. No standard garage wiring is going to run that beast and running on a long cable also will need non standard solutions
Wtf did you not consider the requirements before getting the welder?


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## Sideways (27 Aug 2022)

In industry it is annoyingly common that when contractors rock up on site, they find themselves a nearbye fusebox and wire their welder straight into a breaker.
DO NOT DO THIS. IT'S NOT SAFE. I'VE THROWN CONTRACTORS OFF SITE FOR DOING IT.

The reason they do so is that big welders need a lot of current and ordinary power sockets aren't up to it.
Your specs say the welder needs 29.6Amps of "rated input current".
Show these specs to the sparky and ask them to install a 32A blue CE industrial socket for you with a built in switch. 
He will need to run fixed wires from that socket back to your fusebox and wire it into it's own 32Amp circuit breaker.
You can also ask him to make you up a 32Amp extension cable of whatever length in rubber flex 
4mm2 cable might do, but it does depend on the length. Matching 32A blue plug and socket on the end. And fit a 32A blue plug on the welder's flex.
You are right about "voltage drop" but he will deal with that and the worst that will happen is that your welder is very slightly underpowered if you lose a few volts over the length of the extension cable.

Those efficiency and cos phi figures are interesting. They tell us that 2.5kW of power flows in and back out of the welder in use without being consumed. It uses a little over 4kW of real power but the extra 2.5kW flow in and out of the machine and the wires have to be big enough to cope with that.

Also, you get to run your welder at full power for 2.5 minutes in every 10 minutes. Then 7.5 minutes rest to cool down. So on the thick stuff, weld one stick then take a break.

If I remember from welding class a couple of years back we were mostly working around 120 to 130 A output for stick welding 4mm sheet.


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## guineafowl21 (27 Aug 2022)

What plug is your welder supplied with?

My 200A inverter welder (fairly decent quality) was supplied with a 16A blue commando plug, so I installed a 16A supply to suit, ditto extension cable. I did cock an eye at the max current and power ratings on the plate, which were similarly high, but in practice they don’t seem to trouble the setup. Perhaps they’re momentary peak values.

I’ve had it cranked up to 180A and working reasonably hard, and have not had a trip yet (B-type breaker).


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## pe2dave (27 Aug 2022)

@Splitlight the figures you show need interpreting? Particularly Rated input power (KVA) | 6.8. 
As others have said, that is approx 16 amps at mains voltage, which (may be) trouble. 
If you are working in your garage what current (amperes) is provided? Mine is 32A cable to the garage, which (safety says) is not enough to feed your existing kit and a 32 amp welder. 
If you've 'plenty of current' to spare, fine, add a 32 amp breaker, feed to a commando socket (because of the high current) and you're away. A normal 13 amp socket is likely to burn out with such a high current. 
Bottom line, IMHO it's a job for an electrician. And not a cowboy, you'll need a certificate of conformance when he's done (if you ever need to sell the house). 
HTH


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## guineafowl21 (27 Aug 2022)

Further to this, I’ve found the manual for my 200A inverter welder. 

The ratings quoted are peak values, for example, my max current is listed as 47A. 
However, the correct supply is a 16A commando.

My advice is to get your electrician to install according to manufacturer’s instructions - there is no way, imho, that a little 160A welder needs a 32A supply.


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## Spectric (27 Aug 2022)

If you work along the lines that (volts in) times (current in) will equal (volts out) times (current out) if 100% efficient then you get 4224 watts output on maximum so with a 230 volt supply you will draw 18 amps. As @guineafowl21 has said it is only a small stick welder and with a low duty cycle so unless it is has very poor efficiency then it should be ok on a 16 amp supply unless you are going to run it at maximum using 4mm rods.


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## Sideways (27 Aug 2022)

Get an electrician in. It's a bit annoying that advice on here is becoming unreliable because people are talking about their own personal experiences and about THEIR machines which aren't yours.
That's interesting but it isn't any basis for designing a safe electrical installation.
Use a qualified electrician to do certified work and it should be safe. If not, you will have asked for a copy of their (in date) liability insurance before they began, right, so you have some comeback if it overheats and starts a fire.

6800 KVA rated input power divided by 240V (UK mains) = 28.33 Amps

That's a 77% overload on a 16A supply.
You will only be able to apply that for maybe 3 minutes before your welder overheats and shuts down (or melts), so you'll most likely get away with it. Should you plan to work this way ?
Hell no !
If your circuit trips out when your welder is stinking hot at the end of 2.5 minutes on max and the cooling fan suddenly stops too, you could cook your welder.
It won't cost much more to put in a 32A circuit than a 16A, just a few £ extra on materials, so do it right.


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## Splitlight (27 Aug 2022)

Sideways said:


> Get an electrician in. It's a bit annoying that advice on here is becoming unreliable because people are talking about their own personal experiences and about THEIR machines which aren't yours.
> That's interesting but it isn't any basis for designing a safe electrical installation.
> Use a qualified electrician to do certified work and it should be safe. If not, you will have asked for a copy of their (in date) liability insurance before they began, right, so you have some comeback if it overheats and starts a fire.
> 
> ...



Thanks for this, I appreciate your comment.

My original post was to gauge the kind of things I should be installing for my welder before I spoke to the electrician to have a (reasonably) informed conversation with him, and from reviews and people on here, it seems it could be used in short bursts okay.. 

However I just want it set up properly so I have peace of mind and can use the welder to its full capacity (even though I likely won't often, as it is a fairly powerful machine, apparently).

I chose this machine over the 120A previous model just because it was £10 more and I thought why not lol.

So thanks again, I'll ask the electrician about putting in a 32A supply as you say, assuming my garage can accommodate this.


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## Spectric (27 Aug 2022)

Having worked in Industrial electrical and used several welders over the years, a lot of the old oxford buzz boxes until I went to a 300 amp TIG then a 160 amp machine is nothing on the big side. The specifications do not match the Hyundai MMA-160! 

This is for a 180 amp sealey machine, where a 16 amp supply may be needed. 







For the Hyundai MMA 160 then look at the picture and that blue single phase plug is 16 amps, 









If you look at this one, also a MMA 160 it states a 13 amp input







So if the OP is buying the Hyundai MMA 160 amp machine they certainly do not need a 32 amp socket. 

Is this the machine you are buying


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## Spectric (27 Aug 2022)

Sideways said:


> Get an electrician in. It's a bit annoying that advice on here is becoming unreliable because people are talking about their own personal experiences and about THEIR machines which aren't yours.


But electrical theory, circuit design and load calculations are the same anywhere in the uk, all that is missing in most cases is knowing the design and state of the current installation, which is where you need the proper electrician and not a domestic installer.


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## Splitlight (27 Aug 2022)

Spectric said:


> Having worked in Industrial electrical and used several welders over the years, a lot of the old oxford buzz boxes until I went to a 300 amp TIG then a 160 amp machine is nothing on the big side. The specifications do not match the Hyundai MMA-160!
> 
> This is for a 180 amp sealey machine, where a 16 amp supply may be needed.
> 
> ...



I have the welder right now, it looks like the first picture and has that type plug.

Now I'm confused about which power supply I need? The instruction manual says exactly what I wrote in my original comment. But you're saying the listing on websites say it doesn't need a 32A supply?


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## Spectric (27 Aug 2022)

If it has been supplied with a 16 amp plug and in one section it states a 13 amp input then that information saying it needs a 29.6 amp input is contridictory and why would the manufacturer sell it with the 16 amp plug when it really should have had a 32 amp plug. This is a small portable invertor type welder, aimed at the home / hobby market and once you start selling equipment that needs a 32 amp supply you are heading into industrial / trade territory, the bigger welding plants use two phase 400 volts like my TIG welder. I gather you don't have a 16 amp supply at present, so you will need to get one installed and show the electrician your welder and he will either advise what you need and may even suggest a 13 amp plug but the 16 amp supply may have other uses in the future if you but a planer thicknesser or something that needs that supply.


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## Sideways (27 Aug 2022)

What Spectric has found for us is that that the manufacturer's specifications don't look right for the machine. I agree that the machine pictured is not a very big welder and it's very hard to imagine a 32A supply really being necessary for something that looks quite lightweight as welders go.
This reminds me of old hifi where some manufacturers advertised "peak music power" rather than a more realistic "RMS" power; and the way that very many companies selling dust extractors quote performance figures that are never achievable in real use.

So, good response !
I stand by all my recommendations based on the manufacturers specs, but I think Spectric has done the better job of getting to the bottom of it and I agree that even though they are comprehensive and detailed, the specs look over optimistic / too high.

What next ?
If you doubt the manufacturer, the best way of all is run the machine on full and measure the current it actually takes. But this isn't something you can easily do so personally I'd take a small risk and settle for a 16A circuit.

Apologies all for getting a bit sniffy !


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## sawtooth-9 (27 Aug 2022)

Spectric said:


> If it has been supplied with a 16 amp plug and in one section it states a 13 amp input then that information saying it needs a 29.6 amp input is contridictory and why would the manufacturer sell it with the 16 amp plug when it really should have had a 32 amp plug. This is a small portable invertor type welder, aimed at the home / hobby market and once you start selling equipment that needs a 32 amp supply you are heading into industrial / trade territory, the bigger welding plants use two phase 400 volts like my TIG welder. I gather you don't have a 16 amp supply at present, so you will need to get one installed and show the electrician your welder and he will either advise what you need and may even suggest a 13 amp plug but the 16 amp supply may have other uses in the future if you but a planer thicknesser or something that needs that supply.


I agree with Spectric in this instance.
This is a "small" welder and I would not think it requires 29.6 amps !
I would go back to the supplier and confirm the specifications before spending money on ( possibly ) un necessary heavy duty electrical installations.


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## Ttrees (27 Aug 2022)

Dont listen to me as I have no knowledge and am a joe soap.
I'm just wondering if it would be stated in the manual not to exceed, say 2.5mm rods, and/or not to above a certain amperage if using a household 13a plug?
My 13amp Liddle welder goes up to 120 and has two options, low setting for 1.8/2.0 rods, and high [email protected] 2.5mm.
It doesn't like 3.2 rods.

Does it have a fan?, if not there's likely a thermal cutout which may well kick in after say a half hour of making something, i.e (not flat out welding big long beads)
and take, say a similar time as the lead to cool itself completely, not that my lead ever gets more than just about noticeable amount of heat after long use.

If so, is this just as case of not exceeding what other 13a plugged machines suggest,
and just keep checking the lead for any heat?


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## Phil Pascoe (27 Aug 2022)

I bought a Parweld 160a MMA welder from a member here. It should be on a 16a circuit, apparently, but so long as smaller rods are used will work quite happily on a 13a plug, so I was informed (I've yet to use it).


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## chaoticbob (28 Aug 2022)

Phil Pascoe said:


> I bought a Parweld 160a MMA welder from a member here. It should be on a 16a circuit, apparently, but so long as smaller rods are used will work quite happily on a 13a plug, so I was informed (I've yet to use it).


The Parweld 160 (I'm the member who sold it to Phil) has similar specs - 7KVA I think. I did a bit of mental arithmetic before I bought and thought I needed a 32A (7000/240 = 29 Amps) supply, so as I was setting up my workshop at the time I asked the electrician to put in a dedicated 32A line. I explained why I wanted it and he gave me a sort of pitying look, but installed it anyway. Then I saw a post from a rep on the (reputable) seller's website in answer to someone asking about power requirements and he said he'd had reports of people running it full whack off a 13A plug without problems. But don't quote me he said!

Hope you'll get on with the welder Phil - it's a nice machine and you have a good supply of rods I hope! I put the money towards buying a MIG which suits my needs better at the moment.
Rob.


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## Crazy Dave (28 Aug 2022)

Don't worry too much about the comments here as it's just going to confuse you.
I've run a stick welder from a 13a wall socket with a standard 13a amp fuse fitted in a standard 13a plug and you could do the same but be aware that you will be limited to the size of metal you'll be able to weld and have to limit yourself to light gauge rods. If you were to turn the power up too high the fuse will blow, simple, no harm will come to anything but you may have to release a stuck rod.

I would never use an extension lead with a welder also forget about welding outside as the arc created could blind someone should they have a look at what you're doing without eye protection and if weld splash was to fly off and land in some combustible material you wouldn't notice until you lifted your mask and you could have a fire on your hands.

Eye protection, you may find that after your first weld that you can't see it properly after removing your mask, if your eyes are affected by the welding stop and get a darker glass before continuing. My eyes have been damaged by welding with the wrong glass, not my fault as my employer didn't believe me when I told him I was getting spots in front of my eyes. They did get me a darker glass but the damage was already done.
I went from a 9 to a 13 which is much darker and I was the only person who could see through it, strange but true so be warned.

Advice, create a welding booth with canvas tarps that have a fire proof coating and install extraction to take the fumes away. You'll need at least two curtains (if you work in a corner) so that you can contain any weld splash and protect others from the arc.

Hope this helps and remember safety first.


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## Dave Moore (28 Aug 2022)

I agree with crazydave, don’t put an extension in the mains if you can help it, much better to use an extension on the welding cables and don’t coil the cables either. We had a 240/110v welding plant for stick, tig (on carbon, stainless steel and aluminium) never a problem even on big pipes although no good on 110v.


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## dickm (28 Aug 2022)

Dave Moore said:


> I agree with crazydave, don’t put an extension in the mains if you can help it, much better to use an extension on the welding cables and don’t coil the cables either. We had a 240/110v welding plant for stick, tig (on carbon, stainless steel and aluminium) never a problem even on big pipes although no good on 110v.


One caveat to that. When we moved up here, my 100amp Oxford buzz box would occasionally trip the circuit when it was switched on. A knowledgeable electronics Prof ex-colleague explained to me that the big inductance of the transformer meant that on start up, it could look to the circuit breaker as though it was presenting negative resistance (I think that's what he said) hence a momentary very high draw. Running it off a thick extension lead seems to provide enough resistance on start-up to avoid the problem, so that's what I always do. 
One other tip; if you do metalwork in the same shed as your woodwork, be *****y careful about sparks, and ALWAYS do a good check when you've finished to make sure nothing is smouldering. Of course, if you have a squeaky clean, sawdust/chip free shop, you should be OK!


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## ChaiLatte (28 Aug 2022)

dickm said:


> Running it off a thick extension lead seems to provide enough resistance on start-up to avoid the problem



You might have to discuss that with your friendly professor. A thick extension lead will have less resistance per unit length than a thin one. Conductance is proportonal to cross-sectional area. Resistance is the inverse of conductance.

Also, since his welder is an inverter, how much relevance do the electrical characteristics of a transformer machine (buzz box) have to his situation?


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## guineafowl21 (28 Aug 2022)

Nothing like an electrical installation thread for a spirited discussion.


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## Dave Moore (29 Aug 2022)

dickm said:


> One caveat to that. When we moved up here, my 100amp Oxford buzz box would occasionally trip the circuit when it was switched on. A knowledgeable electronics Prof ex-colleague explained to me that the big inductance of the transformer meant that on start up, it could look to the circuit breaker as though it was presenting negative resistance (I think that's what he said) hence a momentary very high draw. Running it off a thick extension lead seems to provide enough resistance on start-up to avoid the problem, so that's what I always do.
> One other tip; if you do metalwork in the same shed as your woodwork, be *****y careful about sparks, and ALWAYS do a good check when you've finished to make sure nothing is smouldering. Of course, if you have a squeaky clean, sawdust/chip free shop, you should be OK!


I had a Myford ML8 lathe that used to trip the breaker on start up due to surge so went to electrical suppliers who sold me a MCB of same rating but one that didn’t trip on the surge. Don’t know how that works but it sorted the problem.


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## sawtooth-9 (29 Aug 2022)

guineafowl21 said:


> Nothing like an electrical installation thread for a spirited discussion.


Yep !
Certainly seems to get the "sparks" flying.


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## guineafowl21 (29 Aug 2022)

Dave Moore said:


> I had a Myford ML8 lathe that used to trip the breaker on start up due to surge so went to electrical suppliers who sold me a MCB of same rating but one that didn’t trip on the surge. Don’t know how that works but it sorted the problem.


You swapped a B type breaker for a C type, which allows a larger momentary surge. You’re meant to check the circuit is suitable for the change.

Here come 100 posts about loop impedance...

Run.


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## nickds1 (29 Aug 2022)

Not going to enter into the general discussion, but will issue a warning...

If using a long extension cable on a reel, unravel it all before use, especially if using a high frequency load...

This is not about driving the load, it's more about fault conditions and the inductance of the protective ground (earth) cable if it's coiled.

I've received very nasty deep burns as a result of a spark jump from supposedly earthed equipment that was powered from an extension that was still largely coiled on its reel.

Uncoil the extension and the protective ground has far lower inductance so gives better protection, especially to high frequency energy if around inverters, stuff generating arcs etc.

Just saying...

Edit: there is at least one other good reason to uncoil extension leads: heat

Coiled leads don't allow normal heat loss from cables, so the cable current capacity can be seriously derated and cause the insulation to become damaged and even melt at well below the fused level...


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## dickm (29 Aug 2022)

ChaiLatte said:


> You might have to discuss that with your friendly professor. A thick extension lead will have less resistance per unit length than a thin one. Conductance is proportonal to cross-sectional area. Resistance is the inverse of conductance.
> 
> Also, since his welder is an inverter, how much relevance do the electrical characteristics of a transformer machine (buzz box) have to his situation?


Cable thickness is a compromise. Too thin and it might overheat, too thick and it might not have enough resistance to do the trick. Agree about uncoiling; important point. Tried it with my extension lead and it worked, which is enough for me. Sadly, old colleague is no longer with us, so further discussion would need a ?clairvoyant?.
Yes, I agree old Oxford buzzboxes are very different from modern things with inverters etc. (which are well beyond my near-80 year old brain) but thought it was worth a mention for other stick in the muds. (And no, I don't weld in mud!).
Unlike the blacksmith we used when I was a boy. He was standing in a puddle outside the forge and somehow took the full force of his arc welder, which threw him across the yard. When he went home, his wife insisted he go and see the Doctor immediately. Which in those days was possible. Dr Beach looked at him, said "Maldwyn, any normal guy would be dead after that. You're not, so go home and forget about it." Sadly, he wasn't tough enough to resist pancreatic cancer.


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## Spectric (29 Aug 2022)

guineafowl21 said:


> Here come 100 posts about loop impedance


There are no problems doing this if you like living on the edge, but having seen the results when a fault does occur I know the risk are to high but for many non electrical folk they take the view that if it works then all must be ok which upto the point of the fire is true.


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## guineafowl21 (29 Aug 2022)

Spectric said:


> There are no problems doing this if you like living on the edge, but having seen the results when a fault does occur I know the risk are to high but for many non electrical folk they take the view that if it works then all must be ok which upto the point of the fire is true.


You’re right, of course. It was more a joke about electrical threads, where everyone likes to contribute what they know (me included), then descend into arguments about domestic installers and ring circuits. Meanwhile, back at the ranch, the answer for the OP is - blue plug? Blue socket. Refer to electrician.


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## graduate_owner (30 Aug 2022)

nickds1 said:


> Not going to enter into the general discussion, but will issue a warning...
> 
> If using a long extension cable on a reel, unravel it all before use, especially if using a high frequency load...
> 
> ...


Regarding the heat generated, I can remember as a teenager plugging a 3kW fan heater into a partly unwound extension cable. The whole thing melted into a sticky, smelly mess. The cable couldn't be unwound when cool, it was a solid mass of plastic - not that I would have wanted to use it again, even as a teenager.

K


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## Phil Pascoe (30 Aug 2022)

We threw dozens of them out when women wouldn't listen and used vacuum cleaners on nearly fully wound 5a reels.


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## Spectric (30 Aug 2022)

Because we are dealing with Ac a fully wound extension lead is not a pure resistance but a reactance comprising of Inductance and capacitance which can introduce a phase shift in voltage and current which may make maters even worse, never thought about measuring it though as it is easier to just unwind the extension lead.


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