Electric Shower Cold Only in Morning

[Softus]

I can't see the point of estimating or calculating anything, especially approximately - this is a fault-finding exercise.

The point is to find the voltage drop to see if the fault is an undersized cable resulting in under volts at the shower.

I don't think you're given to writing nonsense, bernardgreen, so I presume you're having an off day.

I know that the point is to find the VD - that's why I suggested measuring it.
My point to you was that I can't see the point of estimating or calculating anything, especially cable impedance.

If the local supply is varying in voltage minute by minute then it will be necessary to have two people and mutimeters and read the voltages at the CU and at the shower at the same time.

Overkill. The shower isn't flicking between working and not working on a minute-by-minute basis, so one person and one multimeter is plenty.

 

[bernardgreen]

No I am not having an off-day, or at least I am not aware I am. The method of testing for supply cable volt drop by using an un-loaded neutral as a reference is a very useful one when working single handed.

The time taken to move the multimeter from the CU to the end of cable between readings can play havoc with the measurement of the volt drop. It can even create a ( obviously false ) negative voltage drop. As in the voltage at the end of the cable is higher than the voltage at the CU.

I do not know what type of shower the OP has or whether it has voltage sensing circuitry but I do know that minute to minute voltage variations can hold a device OFF.

The other consideration is looking for a voltage drop when the shower is not switched on. This would indicate another load using the shower's supply cable instead of having its own supply cable.

 

[Softus]

I think you're doing some radical point-missing here.

I was pointing out the lack of wisdom in estimating and calculating, but you seem not to want to stick to the point because you keep introducing new ones that, whilst they might be valid, aren't relevant to the first post I made about measuring VD - the one that you appeared to be replying to.

I officially give up on trying to have a rational e-conversation with you - I just hope that the OP can make sense out of the myriad conflicting things that you're advocating.

 

[Deleted member 64697]

Softus, Can you recommend where I can buy a multimeter with clips? I've tried a few searches and it's a bit mind-boggling

Coniferman, yes it is freezing cold in the morning and not just cooler.

Can I ask whether the suggested voltage drop in the morning would just suddenly appear? The problem didn't appear when it was first fitted. Are you suggesting there is a problem with the shower and/or fuse box which is amplifying the morning voltage drop?

Following the earlier discussion, I am going to get my fuse box updated. Should I also get the time clock updated at the same time?

 

[JohnD]

Better probes have shielded tips to make it difficult for you to touch a live part with your finger or touch two live parts at the same time.

Edited: On second thoughts, the ones I showed are not really suitable for live working at mains voltages, so I withdraw my suggestion.

 

[Softus]

Softus, Can you recommend where I can buy a multimeter with clips? I've tried a few searches and it's a bit mind-boggling

Maplin? For example, this one:
http://www.maplin.co.uk/Module.aspx?ModuleNo=37279&criteria=multimeter&doy=8m10

If you want to spend a bit more and get more features and more quality, then I'd suggest this one:
http://www.maplin.co.uk/Module.aspx?ModuleNo=4401&criteria=multimeter&doy=8m10

and here's a set of leads that include croc clips:
http://www.maplin.co.uk/Module.aspx?ModuleNo=5669&C=Maplin&U=SearchTop&T=TEST LEADS&doy=8m10

Can I ask whether the suggested voltage drop in the morning would just suddenly appear?

Conceivably, but I got the impression that your shower remains inoperative for a sustained period, not just fractions of seconds and/or minutes.

The problem didn't appear when it was first fitted. Are you suggesting there is a problem with the shower and/or fuse box which is amplifying the morning voltage drop?

You're starting to fall into the common trap of trying to forecast both the fault and the cause of it. The purpose of testing, in a strategic way, is to find the fault. Once it's found and fixed it will be possible to have an idea about the possible causes.

Do you utmost to put the causes out of your head for now, and concentrate on checking any assumption that you've made - for example, it's an assumption that the shower is being provided with 240VAC (+/- the tolerance).

It might turn out that you have a highly resistive connection somewhere, and this could even be outside your property.

BTW, if you turn on a high load, like a kettle, or immersion heater, or the shower (when it's working properly), do the lights dim at all?

 

[Deleted member 64697]

Thanks for the suggested multimeters.

Softus, you are correct that my shower is inoperative for a sustained period (i.e., the morning) but I was asking if the problem would just start to happen (i.e., one morning fine and then not from the next). I'm trying to understand what the next step is if the problem is proven by the multimeters - will the new fuse box fix it?

 

[Softus]

I was asking if the problem would just start to happen (i.e., one morning fine and then not from the next).

I'm confused by your question - I thought you'd already said that this is what happened.

I'm trying to understand what the next step is if the problem is proven by the multimeters - will the new fuse box fix it?

This is just what I was alluding to before. The understanding will come when the fault is found.

Imagine that every test outcome led to two further possibilities; after merely four such tests there are sixteen possible outcomes to describe, if you tried to do it at the beginning. And that's if there are merely two possible outcomes per test. This is why it's best to keep things simple and not forecast what happens next.

 

[Deleted member 64697]

OK Softus. My problem did just start, and I'll try and not to think too far ahead as to why it started!

 

[Deleted member 64697]

Sorry for the long wait - the postal strike and a holiday are to blame.

I've now got the measures:

In morning when shower doesn't work:
Switch on: 246
Switch off: 0

In the evening when the shower does work:
Switch on: 244
Switch off: 0

Does this help?

 

[Softus]

Was that phase-neutral or phase-earth?

 

[fireman22]

has there been a power cut to your property that has put your clock further out, and its since this that you are having the problem. just thinking that some how when the time clock is putting the meter into eco 7 mode its not allowing as much current through. its not a voltage problem as your multimeter is giving same (practically) reading

 

[Deleted member 64697]

Softus, what does phase-neutral or phase-earth mean?

Fireman, I don't know of a powercut. The shower was working fine when the bathroom was first finished. It was just as the builder finished the kitchen that I started to notice problems. I don't know that there was a powercut but he would have turned the fusebox off a few times. But this isn't what you mean is it.

 

[fireman22]

that time clock doesn`t look as if its sealed if not i would open it turn dial so its in off peak mode and see if shower works then turn it so its not in off peak mode check shower again. and then you will know if its time clock related.

 

[fireman22]

ah just saw 2nd pic maybe it is sealed, i would still turn it tho