Fusebox - why keeps blowing

[toast1]

I'm trying to get rid of bed bugs with heat so need lots of power. When I did this before, I didn't have a problem, but now the fuse keeps blowing.

It has blown in the past, when too many things are turned on, but this time it keeps blowing all the time, when just a few heaters are turned on.

Otherwise all works fine, as long as too many heaters are not turned on.

Any ideas on how to fix this problem?

 

How can I get it back to allowing much power to be used without blowing?


Thanks

 

 

 

[RichCor]

British WYLEX plug in MCB (B32)

-What country are you in?

 

This circuit shouldd safely carry 230v x 32A (7360 watts total) ...but if the wiring gets hot it could trip it.

 

Edit INFO:

Type B devices are designed to trip at fault currents of 3-5 times rated current (In). For example a 10A device will trip at 30-50A. Type C devices are designed to trip at 5-10 times In (50-100A for a 10A device).

 

 

Edited September 18, 2020 by RichCor

[Crossy]

6 hours ago, toast1 said:

when just a few heaters are turned on.

 

How many is "just a few"?

 

I'm assuming you're in the UK and that circuit is a ring-final.

 

A 3kW heater will pull about 12A so if "a few" is more than three then the MCB is going to be thinking about operating. Probably 40+ minutes before it operates.

 

But, MCBs can get "tired" and operate sooner if they've opened on overload a number of times in the past. You could try a new MCB (NO not a bigger one) but you're really on the point of overloading the circuit.

 

You seem to be fighting an ongoing battle with bed-bugs, why not get the professionals in?

[Puchaiyank]

Your fuse is probably weak from the stress of being overloaded too much.

 

You are asking for trouble!  A blown fuse is a warning...you could start a fire in your home...the wiring also can be stressed to the point of getting so hot that it may start an electrical fire...in your ceiling,  walls and so on.

 

Get a new bed!

[PatOngo]

Fusebox - why keeps blowing

That sucks!

[impulse]

I'm more curious about that black streak from smoke emanating above the 16Amp water heater breaker.

 

Out of curiosity, what size is the wire leading to the 32Amp breaker and what size wire in the room with all the heaters?  If that breaker feeds all the plugs in several rooms, I can see where you may melt the wires in the room where you're plugging in several heaters, even before the breaker trips.  It's not uncommon to see smaller wires spliced into the circuit the further you get from the breaker, under the premise that the further you go, the fewer loads are plugged in downstream.  (Not smart, BTW, just common)

 

[bankruatsteve]

1 hour ago, impulse said:

It's not uncommon to see smaller wires spliced into the circuit the further you get from the breaker, under the premise that the further you go, the fewer loads are plugged in downstream.  (Not smart, BTW, just common)

It's likely that this is a UK installation and that standards are intact.  There is no "downstream" in a ring-final.

[sometimewoodworker]

2 hours ago, impulse said:

It's not uncommon to see smaller wires spliced into the circuit the further you get from the breaker, under the premise that the further you go, the fewer loads are plugged in downstream.  (Not smart, BTW, just common)

That is something I have never seen. I doubt that it’s at all common.

[impulse]

7 hours ago, sometimewoodworker said:

That is something I have never seen. I doubt that it’s at all common.

 

Perhaps not in the UK where there are codes and permits and inspectors.  But I saw it regularly in shops where I worked in Asia.  Especially when the electrical system was expanded to allow more machines.  There was a proper sized wire coming out of the breaker, but they sized any added circuits for the machine they were adding instead of for the breaker.  The operating theory being they didn't need a 2.5mm2 wire to run a small drill press.  Like I said, not smart.  But happened all the time.

 

Given the smoke stain above the 16 Amp breaker in the photo, there's no telling what's going on with the OP's wiring...

 

[sometimewoodworker]

1 minute ago, impulse said:

7 hours ago, sometimewoodworker said:

That is something I have never seen. I doubt that it’s at all common.

 

Perhaps not in the UK where there are codes and permits and inspectors.  But I saw it regularly in shops where I worked in Asia.  Especially when the electrical system was expanded to allow more machines.  There was a proper sized wire coming out of the breaker, but they sized any added circuits for the machine they were adding instead of for the breaker.  The operating theory being they didn't need a 2.5mm2 wire to run a small drill press.  Like I said, not smart.  But happened all the time.

I haven’t spent time in the U.K. for about 30 years mostly in the Asia Pacific region, and none of the wiring I’ve seen has that feature/bug

[toast1]

Thanks for the info.

 

My flat just overloads sometimes when I have too many heaters on, as everything is electric, including the water heater, and if I put the kettle on then - the fuse turns off.

 

So, is it worth investing in a new MCB, or just put up with it?

Thanks

 

[toast1]

Actually, I didn't have this problem before the fuse blew, when there was a short circuit, I think two live wires touched, and after that the fuse overloads easily, so maybe the MCB is damaged. Possible?

thanks

 

[RichCor]

3 minutes ago, toast1 said:

I think two live wires touched, and after that the fuse overloads easily, so maybe the MCB is damaged.

The MCB may be weakened due to multiple trip events, but the wiring may also be damaged if it's encountered direct L/N shorts. An visual inspection of the entire line (where feasible) is in order.

 

Given that this is a very old 'fuse' box that's been converted over to the WYLEX plug-in MCB, a visual inspection of the wiring and all the plug points is probably long overdue.

[Crossy]

When was the last inspection (EICR)?

 

I suggest it's now time to get two lots of "pro's" in, one for the bed bugs and one for the electrics.

 

[Matzzon]

You do know that you must reach a temperature of over 47 degrees celsius in more than 90 minutes to effectively kill all the bed bugs. In other words, that temperature must be in the core of the mattress. That would mean a higher temperature in the room for an extended amount of time, or that you will always sleep with sweat perls for the rest of your life. Probably a good idea to listen to Crossy, and his advice regarding professionals. ???? 

[siam dreamers]

Turn off the breaker and tighten down the screw holding the wire to the breaker, repeat on all the other breakers. This is common practice for an electrician when they open up a breaker box. It is the first thing I do when someone's air conditioner ect. stars to trip breakers. A loose wire causes resistance, causes heat, trips breaker. If that does not work replace breaker.

[toast1]

Interesting, I will try that. 

Good suggestions.

Thanks

 

[donnacha]

Direct a webcam at the fusebox overnight to find out if the bed bugs have figured out a way to flip that switch.

Not many people realize that bed bugs have the same brain size as dolphins.

 

Edited September 21, 2020 by donnacha

[jastheace]

you could 'uprate' the breaker to a D32 (from the current B32 since you may be tempted to replace it anyway). would @Crossy recommend that?

[Crossy]

3 hours ago, jastheace said:

you could 'uprate' the breaker to a D32 (from the current B32 since you may be tempted to replace it anyway). would @Crossy recommend that?

 

It would likely make no difference as this is a relatively long term but small(ish) overload so it's the thermal trip mechanism rather than the magnetic that's operating. Anything over about 10 seconds to trip and the curves are the same.

 

 

I'm not certain if a "C" or "D" curve breaker was ever made for these boards.

[sometimewoodworker]

5 hours ago, jastheace said:

you could 'uprate' the breaker to a D32 (from the current B32 since you may be tempted to replace it anyway). would @Crossy recommend that?

Apart from the point that it will make no difference if it is an overload trip as Crossy has pointed out, and that the breakers are probably not available, it is unlikely that the wiring has the configuration to allow a D curve MCB. 
 

You do realise that in the U.K. you can’t just swap out one type for another without doing the calculations and certification that the swap is still within the regulations.

 

If you do it anyway your house insurance will be void as a minimum.

[sometimewoodworker]

You will need a loop impedance Zs of 0.26 ohms for a 32A D curve to allow a 640A fault current at around 70^oC  and that is extremely unlikely to be achievable in a domestic installation.

 

If you have a TN-C-S the typical Ze is at 0.35 ohms and that is the best case supply. 
 

So in short Never use a type D unless you are capable of doing the required testing and can certify the results.

Edited September 22, 2020 by sometimewoodworker