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libspero

Domestic Electrical Question

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Long story short..

We had to replace the electric shower recently, which we did with a unit of identical (spec'd) power.

Annoyingly it started blowing the fuse so it was ripped out and one of a slightly lower power installed (about 1kw less).

Now this one is still blowing the fuse (albeit about once every couple of months).

I could just strip it out and put an even lower power one in.. but I would prefer if possible just to get the electrics uprated and if anything put in a more powerful shower. Tracing the wiring I think it should be fairly easy to access and replace, but I would need a new uprated fuse/trip.

Because the box we have is from the 30's(?) it has the old fat barrel fused. Presumably this would be condemned these days and a whole new box of trips would need to be fitted. I guess that's not a massive job.. but I don't know if legally they then have to replace any old wiring too? I don't really want to get into ripping up the walls with two small babies here.

Does anyone have any experience of such things?

Should I just give in and get a lower power shower?

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I think you probably need a new fuse box. I'll bet yours is wooden, and is by appointment to to the late HM Queen Victoria.

Not a huge cost, but you are not allowed to fit that sort of thing now. Is the shower more powerful than the last one?

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The original one was 9.5kw (which seemed a little high in the first place).

Replaced like for like, then with an 8.5.

Could drop down to a 7.5kw but would rather up rate the wiring if possible. I'm just trying to understand how big a job this would actually be.

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It'll likely run into a few hundred quid to get an electrician in to replace the fuse box with something more modern. Likely most of your household wiring can stay as is - but it's possible the shower wiring might need to be upgraded.

We had ours done when we moved in (there was no electric shower and we wanted one together with a general check of the house wiring). The ancient house wiring was largely rated as OK as were all of the old style bakelite light switches although they found no earthing for lights so no metal fixtures allowed.

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An old Indian trick I know, is to replace the fuse by a nail. Then your wiring becomes the fuse. Job done. :o

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An old Indian trick I know, is to replace the fuse by a nail. Then your wiring becomes the fuse. Job done. :o

I doubt if there are many 'old' Indians who used that trick. ;)

We had a 170A welder come in for repair once that had a roll pin for a fuse.

Roll_Plug_zpso44mdfnl.jpg

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If it's from the 30s,is that OK to just not bother getting the whole thing re wired? Our place was built in 1954 I think, and I always assumed it was way over due a rewire. Just haven't got around to sorting it out.

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Electricity isn't new, so it's best if your cables aren't too.

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It'll likely run into a few hundred quid to get an electrician in to replace the fuse box with something more modern. Likely most of your household wiring can stay as is - but it's possible the shower wiring might need to be upgraded.

We had ours done when we moved in (there was no electric shower and we wanted one together with a general check of the house wiring). The ancient house wiring was largely rated as OK as were all of the old style bakelite light switches although they found no earthing for lights so no metal fixtures allowed.

Cheers for this (and the other advice).

On that basis it doesn't sound too bad.. I'll get an electrician in to price it up. I just wanted to make sure I wasn't going to find everything condemned on a technicality that was going to require tearing up all the walls at huge expense.

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A good electrician will not "rip you off", and will know the current regulations, and believe me they are legion. Best to have the job done properly. If you do it yourself, it will take five times as long.

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Sounds a bit weird. I'd measure the current draw on the old and new.

The new is supposedly less ... but might have a higher inrush current, maybe its got a pump on it for motor start. I'd measure the inrush current on the new device and see whether I could fit a b type cb.

Only do this if you know what you are doing.

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Sounds a bit weird. I'd measure the current draw on the old and new.

The new is supposedly less ... but might have a higher inrush current, maybe its got a pump on it for motor start. I'd measure the inrush current on the new device and see whether I could fit a b type cb.

Only do this if you know what you are doing.

You can get a clamp on current meter which involves no electrical connection.

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MCB or RCD tripping?

You know a lot about drugs? :blink:;)

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You can get a clamp on current meter which involves no electrical connection.

I dunno how a normal person measures inrush current. I;ve got something called a mains harmonic analyser what does it.

I guess a normal meter might not be able to capture the instantaneous current. Plus you need to be able to switch on at different parts of the mains cycle in order to calculate the highest current draw.

I have some amps that draw over 140A at switch on. Type C it has to be.

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I dunno how a normal person measures inrush current. I;ve got something called a mains harmonic analyser what does it.

I guess a normal meter might not be able to capture the instantaneous current. Plus you need to be able to switch on at different parts of the mains cycle in order to calculate the highest current draw.

I have some amps that draw over 140A at switch on. Type C it has to be.

Whatever they call them now. Sometimes you need a slow breaker for inductive loads. Can't imagine a shower needs that.

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Whatever they call them now. Sometimes you need a slow breaker for inductive loads. Can't imagine a shower needs that.

Could do if it has a big power pump on it. Motors can have very large inrush currents.

I have no clue how showers work, but if you imagine it has a "background" current draw of X amps for the heating element, then the pump starts up then that could tip it over the edge.

It all depends so much on the wiring though, like whether anything else is powered off the same fuse, how big the initial fuse is in the first place - if its already +++ amps rated then you might not want to go for more.

Inrush current is just a clue as to what might be causing it, despite the power rating being lower than the original. You really need some decent diagnostics to find out what the deal is and how to come up with the best solution, so unless you know what you are doing, an electrician.

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There's no electric in my bathroom. I just keep coal in it.

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Electric showers work from mains pressure. No pumps involved. If the fuse box and wiring dates from the 30's then it will likely contain some lead sheathed cable and rubber insulated cable. The rubber will have perished by now.

You may be lucky - often the entire wiring was run through conduit and can be replaced like for like without any chopping out. Check in the loft and you should be able to find some conduit visible below the insulation if this is so.

I think you will need a full rewire.

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Electric showers work from mains pressure. No pumps involved. If the fuse box and wiring dates from the 30's then it will likely contain some lead sheathed cable and rubber insulated cable. The rubber will have perished by now.

You may be lucky - often the entire wiring was run through conduit and can be replaced like for like without any chopping out. Check in the loft and you should be able to find some conduit visible below the insulation if this is so.

I think you will need a full rewire.

Rubbish.

Google "shower with built in pump". Some showers do work only on mains pressure, but not all of them. These days there is an increasing trend towards power showers and these often have pumps.

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