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Is insulation standard or does it vary? If I have a wire with 2 14-gauge wires inside a second plastic sheath will it handle higher voltage than the technical rating of 110V? I want to use it in a 220V country.

Please note that this is just a set of lamp sockets and the bulbs will be local ones rated at the same power for our voltage, therefore neither power not current will be an issue as power remains the same and current is half at the double voltage. So I am only asking about the insulation.

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    \$\begingroup\$ Still working on your 110v light string? Think about this. Those light strings aren't rated for 220V. If there's an accident (shock, fire, what have you) and the lights aren't approved for 220V, you will be faced with proving that it was safe to use them on 220V. If you can't, you might be held liable for whatever death or damage occurred. Is a $130 string of lights worth the risk of being sued for wrongful death? Worst case, contact the manufacturer (americanlighting.com) and ask them about your particular model. \$\endgroup\$ – JRE Jul 24 '15 at 9:31
  • \$\begingroup\$ If it's rated for 110 volts and you elect to use it at 220 volts, then not only are you probably breaking that country's laws, if something should go awry you could very likely wind up in jail. Or worse. Why not just rewire it with the right stuff and make any potential problems go away? \$\endgroup\$ – EM Fields Jul 24 '15 at 9:37
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    \$\begingroup\$ Insulation varies. "14-gauge" wire could beo anything from bare copper to thick insulation for many kV. Unless you have proof otherwise, you must assume your 110V rated wire is positively unsafe at 220V. \$\endgroup\$ – Brian Drummond Jul 24 '15 at 10:10
  • \$\begingroup\$ It isn't just the wire, though. What about the sockets? \$\endgroup\$ – JRE Jul 24 '15 at 10:21
  • \$\begingroup\$ I think in this context "rewire" will amount to "throw away and buy a new one". \$\endgroup\$ – Simon B Jul 24 '15 at 10:21
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No, there is no such thing as standard insulation for a particular wire size.

The wire gauge only tells you the physical size of the wire. From that, and knowing the material (usually copper), you can determine its resistance per length. That in turn tells you how much voltage it will drop for a given current, and how much power it will dissipate. These eventually give you some idea of the maximum current you can use that wire for in your particular situation.

Since you want to use the wire with a higher voltage but the same power, the current will be lower, so it's fine in that regard. The total power delivered is irrelevant here, since any bit of wire only sees the current thru it and the voltage the insulation must be able to withstand.

Using a wire at a higher voltage than it's insulation rating is a bad idea. It may be that this wire is rated for higher insulation than you need, but without a spec you don't know. And no, you can't make assumptions about the insulation rating just because the device was manufactured in a country that uses a high voltage.

Sometimes the insulation rating is written on the outside of the insulation. Look at the cable carefully with a jeweler's loupe. If you don't see anything there, strip back some of the outer insulation and look at the insulation of the individual wires in the cable.

If that all fails to produce a spec, then you have to assume the wire is only good for the voltage the unit it came with is intended operate at. You seem to want people to tell you it's OK to use this wire at higher voltage without additional information, but it's not. It might be capable of the higher voltage, but the consequences of it not being are serious enough that doing so without specific information is a really bad idea.

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  • \$\begingroup\$ Thanks. That is a good answer. I should have been more clear. I discovered the product is a more general product and not specifically made in America so I contacted the actual manufacturers and asked. I got my husband to confirm by stripping a little bit of the outer insulation and reading the inside cables - 300V. Without understanding what the problem was, though, I would never have known to just read that! Or to ask what I asked. I do understand about the consequences (I was imagining my husband being electrocuted while changing bulbs) and that is why I asked. I appreciate your answer! \$\endgroup\$ – Elizabeth Jul 24 '15 at 12:30
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So, unfortunately I think the points system here encourages people to answer other issues not asked when they don't actually know the answer.

The correct answer was in the comment from Brian Drummond; there is no standard for insulation and you need the rating for the actual product.

BUT, this was made in China for use anywhere and simply purchased by American companies and is actually rated at 300V. My point is that had I listened to the answers on this site I would have given up and thought I can't use it or spent a fortune on a transformer unnecessarily.

By understanding the relationship between power, current and voltage and investigating the only factor that would make a difference (insulation), I now know that this product is safe, contrary to every piece of advice I have been given.

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    \$\begingroup\$ You've been given the advice that is appropraite given the information available to us. I even checked the American Lighting web site and couldn't find anything that said where the light string was made or anything other than rated for 110V. If you've got proof it was made in China and that it is made for use anywhere, then you've got information you didn't share and which therefore couldn't be used by anyone who could answer your question. \$\endgroup\$ – JRE Jul 24 '15 at 11:00
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    \$\begingroup\$ It isn't so much the point system, as that there are professional engineers on this site who have an interest in seeing that things are done safely and who tend to point out things that a naive user might not know to ask or to consider - especially when those things relate to possible safety and liability issues. \$\endgroup\$ – JRE Jul 24 '15 at 11:03
  • \$\begingroup\$ The good advice you've been given was based on the fact that you stated the wire was rated for 110 volts, and whether it was made in China or anywhere else is irrelevant. If, as you now state, the wire is rated for 300 volts, the information you initially provided was wrong and the fact remains that in response to your original query, the advice you were given was sound. Since you now think you know the product is safe to use based on your investigation, I suppose you know whether the rating refers to DC, RMS AC, or peak AC. If you don't, more study is in order. \$\endgroup\$ – EM Fields Jul 24 '15 at 11:46
  • \$\begingroup\$ No, I said that the seller stated the whole item is for use in 110V but an engineer would know that that is not the whole story. Based on a whole lot of research I now understand the issues at hand and could therefore ask the right people the right question to get the information I needed. I would not withhold that information - why would I even ask the question if I knew the answer? Most of the answers I received here were for questions I did not ask. No one pointed out that the voltage rating could be anything and could just as easily be usable here as not. Or explained why. \$\endgroup\$ – Elizabeth Jul 24 '15 at 12:25
  • \$\begingroup\$ I.e. when someone asks if there is a standard for insulating 14-gauge wire, specifically. The only answer that is needed is the one given by Brian and now Olin. Thanks guys, by the way. \$\endgroup\$ – Elizabeth Jul 24 '15 at 12:27

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