50A supply

Effects · 01-05-2014 9:44am #1

Taking a look at a job installing a shower at the moment. Fuse board looks old enough. Probably about 20-25 years old. The main fuse is a 50A and taking a look at the meter cabinet it looks like the cable from the meter is only a 10sq. Were many houses done like this in the past and is it capable of taking a T90 shower?

01-05-2014 10:09am

Effects wrote: »

Taking a look at a job installing a shower at the moment. Fuse board looks old enough. Probably about 20-25 years old. The main fuse is a 50A and taking a look at the meter cabinet it looks like the cable from the meter is only a 10sq. Were many houses done like this in the past and is it capable of taking a T90 shower?

I have seen houses with 4 sq. tails :eek:

In short, the answer is no.
The tails should be at least 16 sq. and by the sound of it the board needs replacing. There is a reasonable chance that the installation will need to be rewired. It would be best to get a registered electrical contractor to carry out a survey.

tp25 · 01-05-2014 10:10am

I think it is a fire hazard.

rewire

tomdempsey200 · 01-05-2014 10:26am

10sq tails and 50amp fuse was standard on domestic installations before the 16/63

not generally suitable for addition of an instant shower

tomdempsey200 · 01-05-2014 10:27am

tp25 wrote: »

I think it is a fire hazard.

rewire

speculation

you don't know that

homes all over the country are 10sq/50amp with no fires resulting

Effects · 01-05-2014 10:27am

So is it a case that it will probably trip out a lot?

tomdempsey200 · 01-05-2014 10:30am

Effects wrote: »

So is it a case that it will probably trip out a lot?

maybe excessive voltage drop

possible problems with main fuse

and any other unknown issues

if the meter was adjacent to board the tails would be rated for 63amp but best get a REC

Effects · 01-05-2014 10:37am

The main breaker is 63A but I think the old neozed fuse was only 50A.

tomdempsey200 wrote: »

if the meter was adjacent to board the tails would be rated for 63amp but best get a REC

About 4 metres from board to meter.

tomdempsey200 · 01-05-2014 10:47am

Effects wrote: »

The main breaker is 63A but I think the old neozed fuse was only 50A.

About 4 metres from board to meter.

a piece of 10sq clipped to a wall is rated for 63 amps

but then you've other considerations like the board and earthrod and bonding which may be related to size of main ocpd(fuse)

as well as esbn equipment which may or may not be relevant

Effects · 01-05-2014 10:52am

There's no earth to the hotpress so I was going to run a new one up and can't seem to find an earthrod but think it was sunk below the meter box as I can see a cable through the bottom of the box and it runs to the fuseboard. Can't do harm to put a new one in. As regards smoke detectors, there's none at the moment so is it something they have to have done if I'm carrying out the other work or can I just recommend it?

tomdempsey200 · 01-05-2014 10:58am

Effects wrote: »

There's no earth to the hotpress so I was going to run a new one up and can't seem to find an earthrod but think it was sunk below the meter box as I can see a cable through the bottom of the box and it runs to the fuseboard. Can't do harm to put a new one in. As regards smoke detectors, there's none at the moment so is it something they have to have done if I'm carrying out the other work or can I just recommend it?

get a REC and let them upgrade

Sir Arthur Daley · 01-05-2014 9:03pm

Effects wrote: »

There's no earth to the hotpress so I was going to run a new one up

Why do you feel it necessary to do this?

Effects · 02-05-2014 9:41am

Sir Arthur Daley wrote: »

Why do you feel it necessary to do this?

In the past I've always had to bring a 10sq to the hotpress and cross bond everything to that.

Sir Arthur Daley · 02-05-2014 10:33am

Effects wrote: »

In the past I've always had to bring a 10sq to the hotpress and cross bond everything to that.

I havent bonded a hotpress in nearly 15 years, whats the point?

tomdempsey200 · 02-05-2014 10:44am

Sir Arthur Daley wrote: »

I havent bonded a hotpress in nearly 15 years, whats the point?

you you mean when wiring a shower or what?

Sir Arthur Daley · 02-05-2014 10:46am

tomdempsey200 wrote: »

you you mean when wiring a shower or what?

Just a hotpress in general, what bonding would a shower need?

tomdempsey200 · 02-05-2014 10:55am

Sir Arthur Daley wrote: »

Just a hotpress in general, what bonding would a shower need?

none usually

Effects · 02-05-2014 6:14pm

So was I always instructed incorrectly in the past when told to bring a 10 sq to the hotpress?

tomdempsey200 · 02-05-2014 6:29pm

Effects wrote: »

So was I always instructed incorrectly in the past when told to bring a 10 sq to the hotpress?

there's usually some bonding in place

unless the installation needs upgrading

Bruthal · 02-05-2014 8:05pm

Sir Arthur Daley wrote: »

I havent bonded a hotpress in nearly 15 years, whats the point?

The main point of it is to reduce or eliminate the chance of potential differences in different metal parts in an installation.

In neutralized installations this is important for keeping everything at equal potential in the event of neutral failure upstream of the installation neutralizing point.

Sir Arthur Daley · 13-05-2014 10:18pm

Bruthal wrote: »

The main point of it is to reduce or eliminate the chance of potential differences in different metal parts in an installation.

In neutralized installations this is important for keeping everything at equal potential in the event of neutral failure upstream of the installation neutralizing point.

Hot-presses now and with a long time only use short bits of copper, the rest of a plumbing installation would be plastic pipe e.g qualplex or acorn. If you bond these bits of copper you are introducing a path by which an electrical charge could become present on metal, which, in the absence of the earth conductor, would have no possible means of generating or becoming charged with voltage.
If an electric immersion heater is fitted to the cylinder it must of course be earthed, as is the case with every electrical appliance, but the earth in the circuit supplying the immersion heater complies with ETCI Wiring Rules.

Bruthal · 13-05-2014 10:31pm

Well you can avoid hot press bonding if you like, thats up to you.

If the cylinder is indeed isolated from all else, that won't be easily proven.

But besides that, a bonded cylinder will pose little risk, as the events leading to the bonding rising above 0v, such as a failed neutral pre neutraslizing point, will have all properly earthed metal in the house at equal potential. And that's what is preferable, not different metals at different potentials.

Still though, with all the qualpex now, its not quite as it used to be.

tomdempsey200 · 13-05-2014 10:41pm

Sir Arthur Daley wrote: »

Hot-presses now and with a long time only use short bits of copper, the rest of a plumbing installation would be plastic pipe e.g qualplex or acorn. If you bond these bits of copper you are introducing a path by which an electrical charge could become present on metal, which, in the absence of the earth conductor, would have no possible means of generating or becoming charged with voltage.
If an electric immersion heater is fitted to the cylinder it must of course be earthed, as is the case with every electrical appliance, but the earth in the circuit supplying the immersion heater complies with ETCI Wiring Rules.

yes there is no need to bond a copper cylinder in isolation

but not all houses are plumbed in plastic by a long shot

tomdempsey200 · 13-05-2014 10:43pm

Bruthal wrote: »

Well you can avoid hot press bonding if you like, thats up to you.

If the cylinder is indeed isolated from all else, that won't be easily proven.

shouldnt be hard to prove

Sir Arthur Daley · 13-05-2014 10:47pm

Bruthal wrote: »

Well you can avoid hot press bonding if you like, thats up to you.

Its not my personal choice, bonding a hotpress with visible stubs of copper joined to plastic pipes which go throughout the installation is the wrong thing to do. Its the same as treating it as a radiator or bath that is plumbed with plastic pipe.

Bruthal · 13-05-2014 10:55pm

Sir Arthur Daley wrote: »

Its not my personal choice, bonding a hotpress with visible stubs of copper joined to plastic pipes which go throughout the installation is the wrong thing to do. Its the same as treating it as a radiator or bath that is plumbed with plastic pipe.

Radiators are unlikely to ever have immersion heater fitted to them, or motorised valves, shower pumps etc.

If its wrong to bond it, fair enough. I'm wrong then, nothing unusual about that. Its not a contest here. If it was, you're the winner:)

Sir Arthur Daley · 13-05-2014 11:03pm

Bruthal wrote: »

Radiators are unlikely to ever have immersion heater fitted to them, or motorised valves, shower pumps etc.

The earth in the circuit supplying what you have mentioned above is sufficient to earth that device.

If its wrong to bond it, fair enough.

Would you bond a hotpress with visible stubs of copper joined to plastic pipes, immersion fitted also?

Bruthal · 13-05-2014 11:05pm

tomdempsey200 wrote: »

shouldnt be hard to prove

How would you prove it? You're in a house, cylinder is tight in a hot press, maybe hidden pipes at the back? Not as easy in reality as hypothetically.

I have not seen many where you have copper cylinder, and all other pipes leaving it are easily visible, and qualpex.

Bruthal · 13-05-2014 11:16pm

Sir Arthur Daley wrote: »

The earth in the circuit supplying what you have mentioned above is sufficient to earth that device.

I think you miss the point of bonding, judging by that.

Now you have the earthed device, it is possible for potential difference to exist between it and the nearby metal of cylinder, should the device earth potential rise. I guess you will say that's not possible.

Would you bond a hotpress with visible stubs of copper joined to plastic pipes, immersion fitted also?

In my opinion such a cylinder should be bonded. You have said the immersion earth is enough. I have not yet seen a cylinder where every pipe leaving the hot press is qualpex.

tomdempsey200 · 13-05-2014 11:17pm

hotpress bonding is just a convenient location for main bonding of metallic service pipes

if they're there they get a bond

a cylinder with bits of copper doesn't need a bond

the main metallic service pipes may need main bonding somewhere else if only ground floor rads are plumbed in copper

Bruthal · 13-05-2014 11:34pm

tomdempsey200 wrote: »

hotpress bonding is just a convenient location for main bonding of metallic service pipes

Its a good location for potential difference to occur between bonded and unbonded pipes. If you can bond them all somewhere else then no need to do them there, but its hard to do them somewhere else and show they are properly bonded in the location they are easiest to touch,,,, the hot press.

The whole idea of bonding is to lock all metal to the same potential.

If the cylinder us totally isolated with no copper leaving the hot press, no bonding needed there, so arthur is right about that.

50A supply

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