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casing, and they slot into corresponding at each side of the
socket. In addition, the centre of the socket is . So rather than being
the front of the socket, on the same face, the circular area that receives the
plug is from the surrounding casing ...
3 These covers only open when pressure is applied to both by the two of
the plug simultaneously.

c In pairs, describe the different plug and socket formats in the pictures in Exercise
2c.

4a 3 .5 ► Andy and Karin, two electrical engineers, are evaluating a plug and socket
format in Exercise 2c. Read the conversation and make notes of the advantages and
disadvantages of the following features.

1 Plug slots into a recess in the socket:
Advantages
Disadvantages

2 Covers protect live and neutral slots:
Advantages
Disadvantages

Andy: In this format the plug slots into the recess in the socket. That allows it to fit in really
tightly, compared with other designs. Plus, these ridges and grooves on the sides increase the
amount of friction. That helps it to resist pullout forces even more, so it won’t fall out of the
socket.
Karin: Yeah, but at the end of the day, how securely do you want it to be retained? If it’s held in
too hard, that makes it difficult to pull out. Andy: That’s true.
Karin: Plus, it could be dangerous. If you're vacuuming enthusiastically to loud music, let’s say,
and you pull the cord, you actually want the plug to pull out, don’t you? Otherwise you might rip
the cable half way out of the plug, or the appliance.
Andy: So, really, we need to compare the pullout resistance of all the formats.
Karin: And determine what the ideal resistance is.
Andy: Yeah. OK. Erm, what else can we say about this one?
Karin: Well I guess another advantage is, given that the plug's in a recess, if it gets pulled out
just a fraction, and the pins are still live, nothing can physically touch them.
Andy: So you think that’s more effective than having insulators round the tops of the pins?
Karin: I’d say so, yeah.
Andy: This one's also got covers inside the live and neutral slots.
Karin: That's a standard feature on more or less every format, though, isn't it?
Andy: Yeah. But I think it’s something we should look at. I mean, it's obviously a good thing.
Anything that stops children from sticking things in is obviously a good idea. The only problem
with this system is, if the mechanism's too sensitive, it makes it difficult to insert the plug,
sometimes. And that makes it easy to damage. Karin: When people try to force it.
Andy: Exactly ...

b In pairs, discuss the advantages and disadvantages of the plug and socket formats in
Exercise 2c. Use the following phrases from the conversation.
an advantage/disadvantage of this format is ... another advantage/disadvantage is ...
the problem with this system is ... this (shape/format/feature) stops ... from ... -ing

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