Another article in the writing for your input...
2 way mains leadMains leads are available with 2x IEC connectors run from one plug. These save sockets and space when running computers, AV systems, etc.
This article shows how to make these socket saving leads, and discusses how to do so safely.
==The basics== This lead is just 2 mains leads in one plug. Few people need instructions on how to fit a plug, but when it comes to 2 leads in one it isn't as easy, and some extra issues need considering.
For one example, everything only just fits into the plug, so its necessary to get the wires the right length and lay the wires out properly in the plug. Failure to do this usually results in a plug lid that won't fit back on. Best practice is often ignored with a single lead, but with two its necessary or the plug won't go together.
==Parts== First you need 2 mains leads. These need to have the same outer diameter [[flex|wire]]. It looks much neater if they're the same length and style too.
[[image:Lead - wires fit 678-3.jpg|thumb|Checking the flexes fit]] And you need a plug - but a lot of plugs won't work. You need one that you can get both the leads into, side by side. It doesn't matter if the fit is rather tight, but they do need to go in. Avoid any (old) plug with a fibre cordgrip, these old cordgrips are entirely inadequate for twin leads. Also avoid any plug with cordgrips that you just press the flex into, these are unable to grip 2 leads.==Tools==
- Wire cutters to cut the wire.
- [[Knives|Knife]] or [[Scissors|scissors]] to strip it
- Small [[screwdrivers|screwdriver]]
==Construction== Cut the plugs off the 2 mains leads.
Strip enough of the outer pvc sheath off each lead.
[[image:Lead - cordgrip 679-3.jpg|thumb|Flexes in cordgrip - note position of lives & neutrals]]Fit both leads into the cordgrip, and tighten it up, making sure it grips both [[flex]]es firmly. Position the flexes correctly, so that the live is on the right and neutral on the left for both flexes. There won't be space later to have wires crossing over each other unnecessarily.
The easiest way to fit the flex into the cordgrip is to remove one [[screws|screw]] completely, and undo the other as far as it goes. Push the [[flex]]es in firmly, get them lined up evenly side by side, not one above the other, before doing up both sides of the cordgrip. The [[screwdrivers|screwdriver]] can be used to lever the flexes into the right position. Tug on each flex to be sure its gripped firm.
If the plug won't grip both leads firmly, now is the time to reject it. You'll only waste time otherwise.
[[image:Lead - lives ready 685-3.jpg|thumb|Lives ready to insert, terminal fully open]]Now fit the pairs of wires to each plug terminal. # Cut the insulation to the correct length so there's no excess length anywhere, and strip to leave about 1cm of bare copper wire at each wire end. # For each wire pair, check the strands are fully untwisted, place the
2 wires together and twist them as one. Double over the end, using your nail to get a sharp bend. If necessary press on the resulting folded wire to minimise its width. # Its generally easiest to fit the [[Earthing types|earths]] first, then lives then neutrals. The lives are the least easy to work with, as they're so short. # Before inserting the wires into each terminal, make sure the plug [[screws]] are undone enough to give the full width of opening for each terminal. You won't get far if you skip this. [[image:Lead - all in 686-3.jpg|thumb|Wirea all in place]] Press all the wires down into position as you go. If you make a mistake on any wire length, redo it. Its very tempting to say who cares, that'll work fine, but IME any slack wire normally results in it being impossible to fit all the wires in at a later stage. The small screwdriver is useful for pressing the wires down - its usually a fairly tight fit. [[image: - - - fuse in|thumb|Fuse in]] Fit a suitable [[fuse]] - 5A for IEC connectors, 2A or 3A for figure of 8 leads. Don't put 13A fuses in these leads.Fit the plug lid. You might find a little wire repositioning is needed, the screwdriver's useful for pressing wires into place.
[[image:Lead - finished 688-5.jpg|thumb|Finished lead]] You now have a lead!===Wire touble?=== [[flex|Wires]] too long should be cut to fit. If you get one too short, gotta start again. There isn't normally enough room to accomodate wires the wrong length.
==Safety== A question often asked is how safe these leads are. The short answer is perfectly safe if good practice is followed, but sometimes not if it isn't.
Double leads are available from retail outlets such as computer sellers and electrical shops, they conform to all relevant legislation and pass PAT tests. The leads discussed here are constructed a little differently, and the following questions are sometimes raised:
===One lead unplugged=== What happens if one lead is unplugged, is it safe lying on the floor?
An unplugged end is touch safe, but can be a risk to small children and animals. Two way leads are recommended for use where this won't occur. So they're suitable for computer systems, AV systems, hifis etc, but aren't so well suited to assorted portable appliances that may get unplugged individually. This is equally true of ready made and home made leads.
===Plugs aren't designed for 2 flexes=== So is it safe?
There are 2 things affected by this: terminals and cordgrip.
====Terminals==== The terminals in plugs work safely with any wire size upto the biggest that fits into the terminal. If it goes in, all is good.
====Cordgrips===== Cordgrips are another matter. Many plug cordgrips are unable to firmly grip 2 flexes, and such plugs should not be used. The functions of a cordgrip are # to stop the wire moving around in the plug, making the terminals come loose # To prevent the wire being pulled out
A robust and well sized cordgrip can do this with 2 flexes no problem. Its very simple to check whether your chosen cordgrip is doing its job, so all is well as long as you check this when making the lead.
- Both flexes should be gripped firm
- The cordgrip [[screws]] must go right the way through the plastic cord grip strip.
- The old fibre cordgrip strips aren't strong enough
- screwless cordgrips don't work with 2 flexes.
===2 leads one fuse=== Is it safe having 2 leads on one [[fuse]]?
This is how it is with extension leads, adaptors and multi-way sockets. Its not a safety problem.
===Overload=== Can these leads be overloaded?
Its physically possible to put 2 kettle leads in one plug, fit a 13A fuse and draw 25A, so yes, it can be done if the potential issues are ignored. The fuse in the plug provides some degree of overcurrent protection, but not necessarily enough in every case. A 13A fuse for example will pass over 20A for half an hour, failing to protect the plug.
To be totally safe the leads are not recommended for high power uses, and a 5A [[fuse]] or less is best to ensure the fuse provides complete protection for plug and socket. A 5A plug fuse won't pass enough current for enough time to damage a mains plug - higher rated fuses can.
This issue is the same for factory made leads as home made ones, and with a little basic care the leads are safe.
===Summary=== These leads are legal and safe if constructed and used in accordance with good practice. However there are safety issues that can occur if the extra issues of these leads are overlooked.
==See Also==
- [[Special:Allpages|Wiki Contents]]
- [[Special:Categories|Wiki Subject Categories]]
[[Category:Electrical]] [[Category:Safety]] [[Category:Tidy up]]
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