Extra CPC on Shower Circuit

[acvc]

Called out this morn, burning smell from shower pullswitch.

Got there, inspected, arcing on line conductor load side in switch. Loose connection or moisture. re-terminated and connected. Tested from shower, conductors disconnected. Results satisfactory. Did Minor Works Cert for them.

Shower circuit: split from mains in Henley blocks to sep rcd enclosure - 30mA, then 40A mcb.

Confusing part coming up. Why was there an extra 4mm cpc run through the switch and shower? I initially thought perhaps poorZs. Test showed the extra cpc only made 0.02ohms difference to Zs. Also, this extra cpc didn't run back to the main earth in the shower rcd unit. I presume it went back to the main c/u (in a bit of a hurry, didn't have time to check inside main c/u).

Is it do do with the time/current characteristics of the 40A Type B being 200A for 5sec, and the 4mm cpc in the 6242Y not being able to handle this?

I've done a few showers, seen a few more, but not come across this before. Perhaps 16thEd Regs?

Thanks chaps, any advice gratefully accepted.

 

[zupos40]

Called out this morn, burning smell from shower pullswitch.

Got there, inspected, arcing on line conductor load side in switch. Loose connection or moisture. re-terminated and connected. Tested from shower, conductors disconnected. Results satisfactory. Did Minor Works Cert for them.

Shower circuit: split from mains in Henley blocks to sep rcd enclosure - 30mA, then 40A mcb.

Confusing part coming up. Why was there an extra 4mm cpc run through the switch and shower? I initially thought perhaps poorZs. Test showed the extra cpc only made 0.02ohms difference to Zs. Also, this extra cpc didn't run back to the main earth in the shower rcd unit. I presume it went back to the main c/u (in a bit of a hurry, didn't have time to check inside main c/u).

Is it do do with the time/current characteristics of the 40A Type B being 200A for 5sec, and the 4mm cpc in the 6242Y not being able to handle this?

I've done a few showers, seen a few more, but not come across this before. Perhaps 16thEd Regs?

Thanks chaps, any advice gratefully accepted.

It may have been someone attempt at supplementary bonding, I been asked to bond between light and shower outlet if you could touch light from shower, also been asked to bond from shower to shower basin metal waste used to be NICEIC requirement.

 

[acvc]

Doh! Of course. Many thanks for not ripping into me.

 

[Modernelectric]

bonding bathrooms is something that i certainly do not miss! hooray for rcd protection and the 17th edition!

 

[Darkwood]

Although i respect you own judgement and may be teaching you to suck eggs but if you had a loose cable check there is no heat damage to the switch and cable if their is then it would be wise to replace pullswitch and strip back beyond damaged cable when reterminating as the heat changes the properties of the metal and sometimes you loose the contact force within the switch thus expect it to happen again even though terminals tight.