Discussion in 'Electrics UK' started by superiore, 6 Mar 2004.
This topic originated from the How to page called Types of electrical circuits.
can a power shower be wired into a 13amp ring mains by using a spur from a socket?
the pump can
thanks breezer but I was worried that if I use 2.5 cable, the wires inside the pump shower unit look alot thinner than the 2.5 connection I will be making to the socket...is this dangerous for overheating the pump?
Why should the size of the cable supplying a device cause overheating of the device?
This is quite a common thought actually (although not always regarding shower pumps!), and it shows that people are at least thinking about what they are doing rather than blindly following advice.
The simple answer is: when you connect up a device to the mains, it will only draw the current it needs. So in the case of your pump it will draw 2-3 amps, irrespective of the thickness of the supply cable. Even if you used cables as thick as your leg the pump would still draw the same current.
thanks very much you have answered my question and I have connected the shower!!!
Does it? Or does it show that some people have such an A-A-F view of electrics, that they think a large cable will "push" so much current into something that it will be damaged, and therefore a nice safe way to prevent a device from being damaged woud be to use thin cables - that way you can't give it too much electricity.
My worry was,as I thought wrongly, that putting 2.5 socket cable on to the thin wires of the pump inside the shower unit would cause the shower pump unit to burn out. Believe me if I could find an electrician and/or plumber to do this job, I would not be attmepting it myself!
How do you plan to actually connect the pump to the electrical supply?
My point is, it is better that people (well, at least one!) are considering their DIY electrics and asking for considered advice instead of blindly leaping after reading a few posts. Ban, you were not born knowing all about voltage drop, cable ratings and current. I am sure you learned by asking questions. Electrics is not rhetoric so answering a sensible serious question with
does not help anyone!
I still haven't figured out what you have against sheds either!
Adam, whilst I concur with your comments, that it is better to have someone ask rather than go blindly forward, I have a lot of sympathy for Bans position on this.
If a persons knowledge of electricity and circuits is so low that they genuinly believe a larger cable will supply more power than a little one and will thus cause a piece of equipment to suffer damage, then I too must seriously question their ability to undertake the task they are asking about.
I see questions asked on here that make me cringe, I may not always agree with the manner of a reply, but many times I concur with the sentiment.
Electricity does not care who it kills, it does not discriminate unfairly, it will kill without warning if precautions are not taken.
If a person has little or no understanding of electrcity, then they are equally blind to it's dangers, and thus they have no reason to be playing about with electrical equipment and circuits.
This view may seem harsh to DIYers, but I have seen people who have been killed doing DIY and professional installation work, it is not a pretty site, especially when, as I had about 14 months ago, a call to a house in which an 8 years old child died after getting a shock because her father was a DIYer who did not understand what he was doing. He has to live with that, and I have to live with the image of a dead, fried 8 years old.
ELECTRICITY IS DANGEROUS, MESS WITH IT AT YOUR PERIL, BUT ALSO THAT OF YOUR FAMILY.
No, I wasn't and I did, and my statement above about AAF was an attempt to explain why I was concerned about superiore's view that using a thick cable to power his pump would damage it.
Let me give you another example of a dangerous corollary. A few months ago I approached a mini-roundabout, intending to go straight on, and as I got to it there was a car coming the other way, turning right, i.e. across in front of me. So I gave way, and as the driver came round he smiled and waved as if to say "thankyou". That worried me immensely, because it could well be that he thought I didn't have to give way, and had only done so out of courtesy. Which could mean that were the positions reversed, and he didn't think he had to give way, he might have carried straight on and caused an accident.
Note, these are only "could"s and "might have"s, I'm not saying that my conclusions are correct, in the same way that I was only saying that superiore's view that a thick cable would supply too much current could mean that he thought a thin cable would safely limit it. Hence my question:
It wasn't rhetoric, I wanted to know what he thought was going on, and why, and what fundamental understanding of voltage and current he had.
Ah - I don't mean sheds as in wooden garden refuges from SWMBO, I mean places like Bodgit & Quickfit, [sarcasm]with their range of fine products at keen prices, and their helpful and knowledgeable staff[/sarcasm]
I think what we need here is to establish why devices draw current.
When you think about it the mains electricity +/+ and 0 or live and neutral are constantly alternating between a voltag of 230V and -230V. This can be thought of like a mountain, the height of which is the value of 230.
The higher the mountain the more the electrons want to flow.
Now the two connections live and neutral are always different in potential or voltage which makes the electrons want to flow through the shower device.
However, the resistance of the shower is fixed. This means that the current is the same whatever current flows.
The problem is that if you use a cable which cannot take the current or flow of electrons pusing through the wire then the wire melts.
That is it!
what has a mountain to do with it? what is "pusing "
and why are you adding to a post that is 6 months old?
Non! Ce n'est pas le 230V! That is 230V RMS. The actual peaks of the mains voltage are 325V. And it is +/- 10% too. And UK mains voltage is generally still 240V, as that is within tolerance.
Should be noted here, conventional current flows from a more positive potential to a less positive potential. (Electrons actually flow the other way, from the less positive potential to the more positive potential. Cos electrons are negative.)
Typo "the current is the same whatever voltage flows"
More likely the insulation melts But yes, it is dangerous to use a cable that can't take the current.
Sorry to be a pedant, I just have to do this!
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