Does a 50m extension lead need to be fitted with an RCD?

I would say that yes a 50m extension lead should be fitted with an RCD, in any ordinary circumstances.

It might be just acceptable to omit the RCD if the cable is 1.5mm and if the fuse is only 3 amps, but in practice the chance of a larger fuse being fitted latter is significant.

Might be acceptable under the control of a skilled person who ensures that it is only used from fixed sockets protected by an RCD 

Might be acceptable under skilled control if only class 2 appliances are to be used.

Might be acceptable from a small portable generator that cant blow a 13 amp fuse.

But for unsupervised use by ordinary persons an RCD is in my view required.

Most retailers call them "cable tidys" and not extension leads.

Christian Ambler said:

My question is, if I have a 50m extension to test, should I be failing it if it is not fitted with an RCD?

I think the CoP tells us that the answer is no, because it says "this may not be required where RCD protection is provided within the installation"

The reality is that there are many off-the-shelf extension lead assemblies are available that exceed the ratings of Table 10.3 of the CoP, that don't have an RCD built in - but the manufacturer has the option to state that the assembly should only be used with an RCD.

In addition, the user has an option of providing a PRCD if there is no RCD in the installation itself.

The question of whether the product is safe for a particular organisation lies really with the duty holder. You ought to agree with the duty holder in advance of PAT testing, what to do about situations like this. It's really the duty holder's responsibility and decision at the end of the day.

Further, BS EN 61242 (cable reels for domestic and similar use) has maximum lengths of flexible cable as follows:

0.75 sq mm - 30 m
1.0 sq mm - 40 m
1.5 sq mm - 60 m
2.5 sq mm - 100 m

BS EN IEC 61316 (industrial cable reels) permits 80 m for cables up to 6 sq mm csa.

The standards do not require extension reels to incorporate an RCD (although they may do)

Would it be correct to "fail" a product to either of these safety standards, when the standards says they are safe, particularly when the standards are specifically listed as indicating conformity to the essential requirements of the Electrical Equipment (Safety) Regulations 2016 (as amended) ?

I really think it's more about PUWER and where and how they are used in the workplace, not "fail because no RCD built-in".

Thank you for the concise answer, it is much appreciated.

I have spoken to the Dudy Holder, and they have agreed to have in-line RCDs fitted to the extension leads due to the fact we cannot confirm that any installation our engineers go to will have an RCD on the installation, and the environmental factors.

Can I take it that the RCD will be fitted at the supply end of these cables with fault protection rather than additional protection in mind?

Chris Pearson said:

Can I take it that the RCD will be fitted at the supply end of these cables with fault protection rather than additional protection in mind?

Who knows? Neither BS EN 61242 nor BS EN IEC 61316 let us in on that secret (in fact, they don't specify an RCD as per above ... but they might ... but no guarantee ... be based on the assumption that BS 761 generally requires additional protection for socket-outlets rated up to 32 A in the general case)

Nor are we looking at requirements of BS 7671 alone, which effective (bar additional protection) cease at the socket-outlet.

However, a fair bet all things being even.