415V sticker in household meter box

My father has said he has a 415V sticker on the feed into his meter box. From what he's told me there is the normal arrangement of master fuse, meter, then into the house to the consumer unit. The house was built in 1985ish and is detached. I've never seen inside the meterbox myself, only the consumer unit, which looked like a normal run of the mill row of circuit breakers with one master at the end, 100A. If there were three phases in the meterbox I'd expect his description to include a lot more. Now the previous owner did have an ironwork hobby with "high powered equipment", but he was a very frugal sort and I doubt he would have got three phases installed if he didn't absolutely have to - mind you I believe he was the first owner of the house and designed it himself, so maybe it's just as cheap to get three phases when building the property? The reason this has come up is they've just had a 10kW electric shower fitted (used to run from the hot water tank, but that one was old and leaky) and are considering replacing their ageing oil boiler with an electric one, which the electrician fitting the shower warned would require a relay to switch off the boiler so it didn't run at the same time as the shower as he'd run out of juice. When he saw 415V he was wondering if he infact had more phases available.

Reply to
Tough Guy no. 1265
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From what he's told me there is the normal arrangement of master fuse, met er, then into the house to the consumer unit. The house was built in 1985i sh and is detached. I've never seen inside the meterbox myself, only the c onsumer unit, which looked like a normal run of the mill row of circuit bre akers with one master at the end, 100A. If there were three phases in the meterbox I'd expect his description to include a lot more. Now the previou s owner did have an ironwork hobby with "high powered equipment", but he wa s a very frugal sort and I doubt he would have got three phases installed i f he didn't absolutely have to - mind you I believe he was the first owner of the house and designed it himself, so maybe it's just as cheap to get th ree phases when building the property? The reason this has come up is they 've just had a 10kW electric shower fitted (used to run from the hot water tank, but that one was

an electric one, which the electrician fitting the shower warned would req uire a relay to switch off the boiler so it didn't run at the same time as the shower as he'd run out of juice. When he saw 415V he was wondering if he infact had more phases available.

clear piccy wanted

NT

Reply to
tabbypurr

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Ignore BM, this is the right answer. You could well be right, there might or might not be 3 phase available. If the current electrician cannot advise, then you need someone who works on (small) industrial sites. Sounds like perhaps the 3 phase meter has been taken out and replaced with a single phase one.

Reply to
newshound

For a pointless question?

Reply to
ARW

... ask one with greater potential.

Reply to
nemo

if your current one is resisting, or just lacks the capacity, induce a new one.

NT

Reply to
tabbypurr

You don't need three phase for 415v - only two. And at one point it was common to install two phases to allow electric heating.

Reply to
Dave Plowman (News)

Was that not split phase?

It is not the same thing as two lines from a 3 phase as you have 460V on a split line.

Rarer than a 15 year old virgin in Rotherham but they do exist.

Reply to
ARW

This is in the Scottish Highlands and the house was built around 1985. Is it likely to have two phases there? It's not in the middle of nowhere, it's in a village with about 400 houses.

Reply to
Tough Guy no. 1265

If he (or I but I'm not up there) really wanted to know, it's easy enough to peek around and use a multimeter. But at the moment it's just a matter of interest for a possible future electric boiler installation. I was just wondering if houses ever had more than one phase installed or if you had to ask for it.

Reply to
Tough Guy no. 1265

It is possible that the original owner had 3 phase installed complete with appropriate meter to power his interests. A subsequent owner would have then been faced with a higher standing charge and possibly reduced options when shopping around for lower tariffs and so it would have been economic (and possibly free) to have the meter changed to single phase. The way to tell would be to look for three phase and neutral coming in and the probability of two empty fuse carriers with wires going in and none coming out. One has to wonder at the abilities of the sparky who could not have seen that for himself!!

Reply to
Bob Minchin

My father is the second owner. He didn't do such a thing, the first owner must have removed it to sell the house if it was there.

I don't think there are empty fuse carriers lying about, my father would have said something. The only thing I can gather that's different from a normal installation is a 415V sticker on the incoming feed. I think he also said the meter says 240V.

I have no reason to believe a sparky went in there, all a sparky did was fit an electric shower, switching off the master switch on the fusebox inside the house would have sufficed. I'm passing on what my father looked at in the meter box when I was discussing with him the possibility of an electric boiler should his oil boiler break in the near future, and whether he'd have enough juice.

Reply to
Tough Guy no. 1265

Well in that case, changing to 3 phase will likely be expensive and not necessarily based on actual cost from what I've heard others mention.

Reply to
Bob Minchin

If the feed wire coming into his fusebox really is 415V, then a second phase is just sat there. A second fuse holder and another meter won't cost much will it?

Reply to
Tough Guy no. 1265

I've just checked my own meter box, and my master fuse has a 415V rating on it! I definitely only have one phase. Very strange. Why would a master fuse need a 415V rating? If I had three phases, surely I'd have three fuses, one on each phase, so they'd still only need to be rated at 240V each.

Reply to
Tough Guy no. 1265

Answering my own question, I guess those fuses can also be used for three phase installations, with one fuse for each phase. If someone had a big three phase motor that shorted out across two phases, you'd have 415V across two of those fuses in series. One would burst first unless they were absolutely identical, leaving the burst one with 415V across it, so it's designed not to create a spark or an arc inside it with that much voltage.

Reply to
Tough Guy no. 1265

Well the sparks would need to see what sort of supply it was if he was going to fill in an electrical installation certificate for the shower.

Reply to
ARW

What information could he possibly get from the meter box that would be applicable to installing a shower? Everything he needs to connect to is in the consumer unit, and labelled for him.

Reply to
Tough Guy no. 1265

But you need 3 phases. If the fuse holders are not there to terminate the original cables. The two ways you have atm are neutral and one fused live which provides 240v. The 415 sticker is a left over from before.

As I tried to suggest before, the Price for three phase connection is NOT related to the Cost of doing the work. Supply and demand at work here.

Reply to
Bob Minchin

Let's see.

Type of supply (ie earthing arrangements), number and type of live conductors, details of protective device.

More than you think.

Reply to
ARW

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