2 electric showers and melted live wire from relay

[Jberry]

This unit is running two showers. Unit was smoking while one shower was running, never tripped the safety switch. Power to one shower is cut off while the other is in use. Is it ok just to change out the relay that had burned? I'm not an electrician but one will be doing the work. The house is rented and the landlord will be arranging the repairs but I'm afraid he probably wont send someone who's registered

 

[Jberry]

ABB Switchgear is very good.

All that needs is a 230v coil, n/o contactor rated 40A or above. They come with 4 pole but only use 2. It's suitably protected against overload by the 40A MCB. That has overheated either due to contactor failing or poor termination. Just get the contactor and damaged wiring replaced.

Any reason why the power never cut to it?

 

[Jberry]

ABB Switchgear is very good.

All that needs is a 230v coil, n/o contactor rated 40A or above. They come with 4 pole but only use 2. It's suitably protected against overload by the 40A MCB. That has overheated either due to contactor failing or poor termination. Just get the contactor and damaged wiring replaced.

Any reason why the power never cut to it?

The smoking will have been caused by the overheating of the conductor and the consequential burning of the plastic insulation (most likely due to a poor termination). It's unlikely any of the protective devices would trip because electrically the only fault appears to have been a bad termination, there doesn't appear to have been any unwanted connections say between live and neutral or earth which would cause the devices to trip.

Basically it looks like a simple case of bad workmanship when it was installed, but as I said, definitely not the first time this has happened.

As for you wanting to see paperwork from the electrical contractor (I use the term loosely based on what you've said), you're not the person ordering the work so technically you've got no right to see the paperwork.

Thanks for the detailed answer. As for paperwork I really just want to make sure that he doesn't send over someone who has no electrical expertise at all. As he has already done. He sent over someone I knew well and so knew they didnt have the knowledge

 

[Spoon]

Post 12:- 2 electric showers and melted live wire from relay - https://www.electriciansforums.co.uk/threads/2-electric-showers-and-melted-live-wire-from-relay.173190/#post-1524259

8.5 and 9 kW I believe

Ta @SparkyChick . I didn't read inside the quote as I thought the post was an accident, with nothing attached.

 

[Charlie_]

It's a shower priority unit. It will only one run at a time with one taking priority over the other. Terribly installed though!!

Yes I know, I was trying to imply that because of all the badging it may well not be operating as it was designed to

 

[telectrix]

might be an idea to get your local council H&S involved. if i saw that "in the flesh", I'd condemn the lot.

 

[Wilko]

Any reason why the power never cut to it?

Hi - the 40A MCB is designed to not trip at 40A, it's ok with that load. Your 9.5kW shower will draw approx 9500/240 = 40A . So unless both showers went on at once (or some other fault) the MCB will run happily. That contactor is rated at 40A so it should be ok, but it is on its rated max and they do have an operational life limit. From the pics ( ) I suspect a poor termination has caused the overheating, as per @SparkyChick.

 

[MJPD29]

It looks like he fitted that board himself it is brutal

 

[brianmoooore]

If it's a four pole relay, I'd have linked the poles two and two from the start.

 

[Spoon]

If it's a four pole relay, I'd have linked the poles two and two from the start.

It's 3 N/O and 1 N/c

 

[brianmoooore]

It's 3 N/O and 1 N/c

Doesn't look like it by the schematic printed on the front of the relay,but it could be a lower rated contact, intended for latching the relay 'on' in some applications. Obviously check before paralleling them up.

 

[freddo]

All 4 poles are N/O all 4 poles are fully rated. You can tell the fourth pole is fully rated as it is marked 7(13) & 8(14), if it was only marked 13 & 14 it would be a lower rated auxiliary contact.

 

[Spoon]

I stand corrected. It is 4N/O