Making up industrial test adaptors - fusing leads?

[Rockingit]

I make my own ceeform adaptor leads for testing purposes where the 4mm banana leads generally just get plugged into my own MFT which is all internally fused. All ratings and sizes - 16/1 up to 125/3

However, it's occurred to me that technically that's not compliant to GS38 (or certainly not in the spirit of it) and limits the useability. As there's so much available space inside a 63 - 125A plug I really have no excuse to not fit some internal fuses in carriers. What rating/type of inline fuse would people suggest?

 

[SparkySy]

I have some the same that I made for all flavors of ceeform socket with maplins 4mm trailing shrouded banana sockets. But mine also are not GS38 compliant, I had thought of fusing them but couldn't find anything appropriate that would fit in the plug.
Having said that my test leads fused and I would isolate the socket before plugging the adapter in and also the test leads, then turn it back on to preform the test. The 4mm sockets are completely shrouded and the lead from the back of the socket is very minimal. I tried some panel mount banana sockets but couldn't get them to fit nicely so went for the trailing type.
I know there are proper ones a valuable on the market now, I think Kewtech do them!
I know that doesn't help much but I would be interested to see what other people's take on it is and if they come up with better solution, other than buying one!
Sy

 

[DPG]

I would say any circuit formed by using the test plug would involve the test leads, so the fusing in the test leads would be sufficient? The plug on its own is not a test lead as such.

That's my take on it. I'm not saying fusing the plug itself is a bad idea though, especially if someone uses unused test leads with it.

 

[Rockingit]

As ever, these days..... RTFM!!

From GS38:

Test equipment​

Test probes, clips and leads​

9 The test probes, clips and leads used in conjunction with electrical test equipment should be selected to prevent danger. Modern test probes, clips and leads should:
■ conform to the requirements of BS EN 61010-031 or in the case of a 2-pole voltage detector to BS EN 61243-3 (see Further reading);
■ be marked with the rated installation category – CAT II, III, or IV;
■ be marked with the manufacturer’s name or identifying mark; and have the following:
■ probes, and clips, which:
o have finger barriers or are shaped to guard against inadvertent hand contact with the live conductors under test;
o are insulated to leave an exposed metal tip not exceeding 4 mm measured across any surface of the tip. Where practicable it is strongly recommended that this is reduced to 2 mm or less, or that spring- loaded retractable screened probes are used;
o when used with a multimeter, should have suitable high-breaking capacity (hbc), sometimes known as hrc, fuse, or fuses,† with a suitable current rating (usually not exceeding 500 mA), except when used with a loop impedance or RCD tester where a value of 10 A is typically used or a current-limiting resistor and a fuse.**

* BS EN 61010 (see Further reading) defines measurement categories (CAT) as below; these reflect the level of overvoltage that can be expected at the point of measurement:
■ measurement category IV is for measurements performed at the source of the low voltage installation (eg meters, primary overcurrent protection devices etc);
■ measurement category III is for measurements performed in the building installation (eg measurements on distribution boards, socket outlets, permanently connected equipment, etc);
■ measurement category II is for measurements performed on circuits directly connected to the low voltage installation (eg appliances, portable tools, etc).
† Fuses, especially low current (500 mA), can add significant resistance to the test lead (up to 2 ohms). This should be taken into account when using fused leads in conjunction with resistance measuring equipment. When replacing fuses, the correct type and correct current and voltage rating must be used. Glass fuses are not suitable.
** Test equipment which predates the British Standards listed above, or was designed to another standard must be maintained to prevent danger and should comply with the guidance on probes and clips in paragraph 9.