Melted RCD!!!

[SSE]

My mate asked me to look at his board as a funny smell was coming off it. Looked inside & the neutral going into the RCD was melted & so was the switch. It's a split load dual RCD board. The RCD switches are both rated 64A 30mA. My first thought was that it could have just been a loose neutral but then my second though was maybe the switch wasn't the correct rating. On othis side that the RCD protects he has two rings: one is the downstairs sockets & the other is the kitchen sockets, a 40A shower & a lighting circuit. I know these obviously ain't gonna be drawing their full loads at once but is it still too much?

 

[Engineer54]

Sorry guys have no pictures as I just dumped it. I just replaced it like for like. I'll maybe upgrade it to the next size up though just to be sure...thanks for your help.

Haha, ...You'll be lucky to see anywhere near 63A for the whole installation, let alone on half an installation!!!

 

[Marvo]

The neutral is more prone to burned terminations than the live because the load on the neutral is higher. Non-linear loads such as fluorescent lighting and switch mode power supplies found in computers and other electronic devices cause harmonics in the triplen range which are especially likely to cause high currents or even overloading of the neutral. The effects of harmonics are usually more profound further up the distribution network but they can be an issue at the consumer end as well.

All that aside, as E54 says, I doubt very much that overload was the issue. I'd still bet on a poor termination causing the overheating.

 

[Jimmy Boy]

What size the tails from the DNO 16's or 25's ?
J

 

[silver surfer]

The neutral is more prone to burned terminations than the live because the load on the neutral is higher. Non-linear loads such as fluorescent lighting and switch mode power supplies found in computers and other electronic devices cause harmonics in the triplen range which are especially likely to cause high currents or even overloading of the neutral. The effects of harmonics are usually more profound further up the distribution network but they can be an issue at the consumer end as well.

All that aside, as E54 says, I doubt very much that overload was the issue. I'd still bet on a poor termination causing the overheating.

I think it's a domestic single phase installation so the neutral current would be the same.

 

[Elmer BeFuddled]

The neutral is more prone to burned terminations than the live because the load on the neutral is higher. Non-linear loads such as fluorescent lighting and switch mode power supplies found in computers and other electronic devices cause harmonics in the triplen range which are especially likely to cause high currents or even overloading of the neutral. The effects of harmonics are usually more profound further up the distribution network but they can be an issue at the consumer end as well.

I concur (well, if I understood!)

I'd still bet on a poor termination causing the overheating.

I'll agree on that as well, never found a (really) loose live or earth, found loads of really loose neutrals.

 

[SSE]

Haha, ...You'll be lucky to see anywhere near 63A for the whole installation, let alone on half an installation!!!

You not think? Maybe my load judegment is a wee bit impaired! lol. I think it's highly possibly, especially when you have a shower running & two rings all on the same side, including the kitchen ring. I may be wrong though!

What size the tails from the DNO 16's or 25's ?
J

25's mate.

I wonder how long it actually would have gone without tripping something.

 

[Engineer54]

You not think? Maybe my load judegment is a wee bit impaired! lol. I think it's highly possibly, especially when you have a shower running & two rings all on the same side, including the kitchen ring. I may be wrong though!

You wouldn't by any chance want to put down any money on it would you?? lol!!!

 

[SSE]

You wouldn't by any chance want to put down any money on it would you?? lol!!!

Mmm you seem very confident so I'll give it a miss. lol.